Bradley Fighting Vehicle Tow

SUBCOURSE EDITIONMM4814 9

BRADLEY FIGHTING VEHICLE TOW

BRADLEY FIGHTING VEHICLE TOW

Subcourse Number MM4814EDITION 9

United States Army Combined Arms Support CommandFort Lee, VA 23801-1809

8 Credit Hours

Edition Date: August 1989

SUBCOURSE OVERVIEW

This subcourse is designed to give an overview of the Bradley Fighting Vehicle (BFVS), the TOW Subsystem (TSS), and the TOW Subsystem Support Equipment (TSS-SE). Contained within this subcourse are instructions on all assemblies and subassemblies to ensure the student understanding of the overall operation of the Bradley Fighting Vehicle.

There are no prerequisites for this subcourse.

This subcourse reflects the doctrine which was current at the time the subcourse was prepared. In your own work situation, always refer to the latest publications.

The words "he," 'him," "his," and "men," when used in this publication, represent both the masculine and feminine genders unless otherwise stated.

TERMINAL LEARNING OBJECTIVE

TASK: You will identify the characteristics and state the purpose of major assemblies, subassemblies, and associated Test Equipment used to support and train personnel for the Bradley Fighting Vehicle System.

CONDITIONS: You will have this subcourse book and will work without supervision.

STANDARDS: You must make a passing score of 70% on the final examination to receive credit for this subcourse.

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TABLE OF CONTENTS

SectionPage

Subcourse Overview.........................................................i

Lesson 1: Introduction to the Bradley Fighting Vehicle TOW................1

Practice Exercise...............................................9

Answer Key and Feedback........................................12

Lesson 2: Bradley Fighting Vehicle TOW Subsystem Operation...............14

Practice Exercise..............................................36


Lesson 3: TOW Subsystem Operation........................................40



Lesson 4: TOW Subsystem Support Equipment................................62



Lesson 5: Bradley Fighting Vehicle Maintenance Concept..................100

Practice Exercise.............................................109

Answer Key and Feedback.......................................112

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LESSON ONE

INTRODUCTION TO THE BRADLEY FIGHTING VEHICLE TOW

Soldier's Manual Task: 093-411-3910

OVERVIEW

TASK DESCRIPTION:

Direct maintenance on the TOW Bradley Fighting Vehicle System and support equipment.

LEARNING OBJECTIVE:

ACTIONS: When you have completed this lesson, you should be able to identify the purpose and function of the major assemblies and subassemblies of the Bradley Fighting Vehicle.


STANDARDS: You will identify the purpose and function of the major assemblies and subassemblies of the Bradley Fighting Vehicle Weapon System in accordance with the information contained in this subcourse book.

REFERENCES: The material contained in this lesson was derived from the following publications:

TM 9-1425-474-34-1.TM 9-2350-252-10-2.

INTRODUCTION

The Bradley Fighting Vehicle gives the U.S. Soldier the mobile armor protected capability for a fully combined arms team. The Bradley Fighting Vehicle (BFV), an armored personnel carrier, features a stabilized two-man turret that houses its main armaments. Those armaments include the tube-launched, optically-tracked, wire-guided (TOW) heavy anti-tank missile, a 25mm cannon, and a 7.62mm coaxial machine gun. This lesson will introduce you to the functional operation of the Bradley Fighting Vehicle.

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Facts about the Bradley Fighting Vehicle.

The U.S. Army's Bradley Fighting Vehicle System (BFVS) includes the M2 Infantry Fighting Vehicle and the M3 Cavalry Fighting Vehicle. The BFVS is an armored personnel carrier which has a 25MM cannon as the main armament, as well as a 7.62mm machine gun and the TOW anti-tank weapon system. All three weapons are aimed with an Integrated Sight Unit, which has day and night capabilities.

The M2 carries a nine-man crew consisting of commander, gunner, driver, and six additional squad members. It also carries seven TOW anti-tank missiles, 900 rounds of 25mm, 4400 rounds of 7.62mm, and 6720 rounds of 5.56mm ammunition.

The M3 is identical to the M2 in external appearance, with the exception of the firing ports. The interior of the M3 is designed for a five-man crew and the storage is different. The M3 carries twelve TOW missiles, 1500 rounds of 25mm, 7600 of 7.62, and 1680 rounds of 5.56mm ammunition.

Figure 1-1. Bradley Fighting Vehicle.

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Tracking Concept.

The Fighting Vehicle Systems (FVS) Integrated Sight Unit (ISU) is a turret-mounted optical system which provides the means for acquiring and tracking stationary or moving ground targets, as well as low performance aircraft. The commander selects a target, and the gunner detects and tracks the target. The commander controls consist of a weapon and turret control handle with over-ride capability, a relay sight eyepiece, and sight periscopes. The gunner controls include control handles, levers, and hand wheels. They are for manual or power operation of the turret and weapons. The gunner has a periscope with blackout covers.

Figure 1-2. Tracking Concept.

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Tracking Concept.

Missile follows gunners line of sight.

Commander locates target.

Driver stops vehicle without changing direction.

Gunner acquires and tracks target through optics in integrated sight unit.

Gunner fires missile, which automatically guides along gunner line-of-sight.

Figure 1-3. Tracking Concept.

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TOW Subsystem.

The Bradley Fighting Vehicle TOW Subsystem (TSS) is made up of four major components. They are: (1) Integrated Sight Unit (ISU), (2) Command Guidance Electronics (CGE), (3) Power Control Unit (PCU), and (4) TOW Missile Launcher (LHR). A Power Control Unit (PCU) converts +24 volt vehicle power used by the TSS. The PCU is not maintained as part of the TSS. The turret drive system consists of traverse drive gun elevation and TOW elevation drives. All drives can be manually operated by the rotation of hand wheels at the gunner's station.

Figure 1-4. TOW Subsystem.

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TOW Subsystem Support Equipment.

The TOW Subsystem Support Equipment (TSS-SE) provides the means for automatic testing, alinement, and fault isolating the TOW Subsystem in the Bradley Fighting Vehicle. The TSS-SE includes the TOW Subsystem Test Set (TSS-TS), and Basic Sight Assembly Support Equipment (BSA-SE).

The Alinement Breakout Box (ABOB), and Alinement Test Set are used for testing and troubleshooting the TSS-TS. The AN/TAM-3 Night Sight Test Set is used in conjunction with the BSA-SE for basic sight assembly test, alinement, and troubleshooting.

Figure 1-5. TOW Subsystem Support Equipment.

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The TSS Support Equipment outlined in Figure 1-6 indicates the use of the Test Equipment.

Test Equipment Acronyms

ABOB: Alinement Breakout Box.

BSA-SE: Basic Sight Assembly Support Equipment.

BSAC: Basic Sight Assembly Checks.

DMM: Digital Multimeter.

MS: Missile Simulator.

D/NSC: Day/Night Sight Collimator.

TC: Test Collimator.

TSS: TOW Subsystem.

TSS-SE: TOW Subsystem Support Equipment.


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TOW Subsystem (TSS) Maintenance Concept.

The current maintenance concept is based on three levels of maintenance as described below:

1. Unit Maintenance.

At the unit maintenance level, the user can perform the system self-test, the boresight alinement check, and preventive maintenance procedures, and may replace any assembly shown to be defective by self-test.

2. Intermediate Maintenance (DS/GS).

At the direct support maintenance level, maintenance is performed on site by an MOS 27E repairer contact team. The contact team performs the 180-day verification test, inspections, fault isolation, and repairs not performed at the organizational maintenance level. The contact team is also responsible for maintaining and testing (including removal and replacement) of the CGE, the ISU, and the launcher assembly. The MOS 27E repairer at the base shop is responsible for removing and replacing circuit cards and modules from the BSA of the ISU, and repairing and aligning the BSA.

3. Depot Maintenance.

The depot maintenance level is the final and highest level of maintenance. Malfunctions not repairable at the direct support maintenance level are forwarded to a depot for major repairs. Red River Army Depot, Texarkana, Texas, is the depot maintenance facility handling repairs of the CGE and the launcher assembly from units in the Continental United States (CONUS). Sacramento Army Depot, Sacramento, California, is the depot maintenance facility handling repairs of the ISU from units in CONUS. Mainz Army Depot, Mainz, West Germany, is the depot facility handling all repairs from units in Europe.

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LESSON ONE

Practice Exercise

The following items will test your grasp of the material covered in this lesson. There is only one correct answer for each item. When you have completed the exercise, check your answers with the answer key that follows. If you answer any item incorrectly, study again that part of the lesson which contains the portion involved.

Situation: You have been asked by a subordinate the following questions pertaining to the Bradley Fighting Vehicle.

1. What are the three major weapon systems on the Bradley Fighting Vehicle?

A. TOW, 25mm cannon, and 7.62 coaxial machine gun.B. 7.62mm cannon and M16 TOW.C. 7.62mm coaxial machine gun, TOW, and grenade launcher.D. M16A1 rifle, 25mm cannon, and 7.62 coaxial machine gun.

2. What are the four major components of the TOW Subsystem?

A. Integrated sight unit, launcher assembly, power control unit, command guidance electronics.

B. Integrated sight unit, basic sight assembly, launcher assembly, and missile simulator.

C. Test controller, basic sight assembly, basic sight assembly holding fixture, and missile simulator.

D. Basic sight assembly controller, basic sight assembly holding fixture, rail assembly, and missile simulator.

3. At what level of maintenance are basic sight assembly circuit cards replaced?

A. Operator maintenance.B. Organizational maintenance.C. Intermediate maintenance.D. Depot maintenance.

4. What is the purpose of the power control unit?

A. Converts 24 volts for TSS power.B. Converts 24 volts for turret power.C. Converts 24 volts for TOW missile.D. Converts 24 volts for 25mm cannon.

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5. What weapon system uses the Integrated Sight Unit (ISU) for tracking and squiring a target?

A. 25mm cannon, 7.62mm machine gun.B. TOW missile, 25mm cannon.C. 7.62mm machine gun, TOW missile.D. TOW missile, 7.62mm machine gun, 25mm cannon.

6. What is the lowest level of maintenance at which a self-test can be performed on the TOW subsystem?

A. Depot.B. Unit.C. Intermediate.D. Organizational.

7. What level of maintenance provides Contact Support Teams?

A. Unit.B. Depot.C. Intermediate.D. Organizational.

8. Who is responsible for the selection of a target?

A. Gunner.B. Driver.C. Commander.D. ISU operator.

9. What maintenance is performed using the Alinement Breakout Box (ABOB) ?

A. Maintenance of the TSSTS.B. On vehicle maintenance.C. Off vehicle maintenance.D. Alinement of the ISU.

10. How many crew members does the Bradley Fighting Vehicle have?

A. 2B. 4C. 5D. 9

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LESSON ONE

PRACTICE EXERCISE

ANSWER KEY AND FEEDBACK

Item Correct Answer and Feedback

1. A. TOW, 25mm cannon, and 7.62mm machine gun..

The three major weapons on the Bradley Fighting Vehicle are the TOW, 25mm cannon, and the 7.62mm machine gun.(Page 2, Para 1.)

2. A. Integrated sight unit, TOW Missile Launcher, power control unit, and command guidance electronics.

The four major components of the TOW subsystem are the integrated sight unit, TOW Missile Launcher, power control unit, and command guidance electronics. (Page 5, Para. 1.)

3. C. Intermediate.

The circuit cards of the basic sight unit are replaced at the intermediate maintenance level. (Page 8, Para 2.)

4. A. Converts 24 volts for TSS power.

The power control unit is used to convert 24 volts for TSS use. (Page 5, Para 1.)

5. D. TOW missile, 7.62mm machine gun, and 25mm cannon.

The ISU is used for the TOW missile, 7.62mm machine gun, and 25mm cannon to track and acquire targets.(Page 2, Para 1.)

6. B. Unit maintenance.

The unit maintenance level personnel can perform a self-test on the TOW subsystem. (Page 8, Para 1.)

7. C. Intermediate.

Contact Support Teams are provided to the using unit by the intermediate maintenance facility. (Page 8, Para 2.)

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8. C. Commander.

The commander selects the targets to be engaged by the crew of the Bradley Fighting Vehicle. (Page 3, Para 1.)

9. A. Maintenance of the TSSTS.

The maintenance of the TSSTS is performed using the alinement Breakout Box. (Page 6, Para 2.)

10. D. 9.

There are nine (9) members in the crew of the M2 Bradley Fighting Vehicle. (Page 2, Para. 2.)

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LESSON TWO

BRADLEY FIGHTING VEHICLE TOW SUBSYSTEM OPERATION

Soldier's Manual Task 093-411-3910

OVERVIEW

TASK DESCRIPTION:

Direct maintenance on the Bradley Fighting Vehicle System and support equipment.

LEARNING OBJECTIVE:

ACTIONS: When you have completed this lesson, you should be able to locate and identify components of the turret of the Bradley Fighting Vehicle, including the commander's turret controls and the gunner's turret controls.


STANDARDS: You will identify the purpose and function of the turret controls, integrated sight unit, launcher assembly, and the command guidance electronics in accordance with the information contained in this subcourse book.

REFERENCES: The material contained in this lesson was derived from the following publications:

TM 9-1425-474-34-1.TM 9-2350-252-10-2.TM 9-4935-474-14.

INTRODUCTION

The turret in the Bradley Fighting Vehicle is a two-person weapons station. The weapons can be used against low-flying aircraft, gun emplacements, and other targets. The commander or the gunner can select, arm, and fire a 25mm cannon, a 7.62mm coaxial machine gun, or a TOW. This lesson covers only those parts of the turret an MOS 27E repairer needs to know about in order to perform direct support maintenance.

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Modes of Operation.

The TSS has five modes of operation: stowed, ready, prefire, in-flight, and wire-cut.

Stowed.

The launcher can be placed in either the retracted position to stow or an erected position before the missile is fired. In the erected position, the launcher is tilted so that missiles can be loaded from the cargo hatch opening. Armor gives protection from small arms damage to the TOW launcher and the missiles.

In the stowed mode, (Figure 2-1) the launcher assembly is stowed on the left side of the turret, and all power to the launcher assembly is off.

Figure 2-1. Stowed Mode.

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Ready.

In the ready mode (Figure 2-2), the launcher assembly is in the raised position on the left side of the turret. The TOW indicator light on the TOW control box in the turret is lit to show that the TSS is ready to be used. The TOW TEST indicator comes on for 15 seconds and goes off after the TSS has gone through the Built-in Test. The testing function is provided by the BIT circuit card in the CGE. The MISSILE TUBE 1 or MISSILE TUBE 2 indicator light is lit to show which is selected, armed, and ready to be fired.

Figure 2-2. Ready Mode.

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Prefire Mode.

In the prefire mode (Figure 2-3), the TSS has been activated by the gunner or commander pulling the trigger switch on the controls while the TSS is in the ready mode. The prefire mode starts 1.5 seconds before the missile is fired. During this period, the CGE and missile electronics go through a self-balance routine. This self-balance routine ensures that the frequencies for pitch and yaw commands are the same in the CGE and missile electronics for proper guidance of the missile. The gyro inside the missile, which is used to stabilize the missile, is also activated and allowed to come up to speed 30 milliseconds before the missile is fired.

Figure 2-3. Prefire Mode.

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In-Flight Mode.

In the in-flight mode (Figure 2-4), the missile is connected to the CGE by two wires through the launcher assembly. The CGE sends a signal to ignite the missile launch motor which moves the missile out of the launcher assembly. The flight motor then engages and takes over. The pitch and yaw circuit card assemblies provide signals to fly the missile into the ISU line of sight. When the missile enters the ISU field-of view, IR energy from the missile is received by the ISU assembly.

The TOW visual module and error detector circuit card assembly in the ISU then provides signals to the CGE to correct the position of the missile with respect to the ISU line-of-sight. The signals from the ISU go to the yaw and pitch card assemblies. Here they are changed to missile command signals to direct the missile. The G-Bias and CVAC circuit card assembly creates a signal to correct for the pull of gravity on the missile. This signal goes to the pitch and yaw circuit card assemblies and is converted to missile command signals. The output circuit card assembly then combines the missile command signals from the pitch and yaw circuit card assemblies with a carrier frequency so that the signals can be transmitted on the two wires to the missile. The missile electronics allow the missile to respond to the missile command signals.

Figure 2-4. In-Flight Mode.

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Wire-Cut Mode.

The final mode of operation for the TSS (Figure 2-5) is the wire-cut. This function is completed by the timing signal from the programmer circuit card assembly 23 seconds after launch. This signal goes to the squib circuit card assembly and triggers the squib wire-cut signal which causes a squib in the missile container to cut the wires to the missile. The wire can also be cut using the TOW ABORT switch on the turret control box or by selecting another missile.

Figure 2-5. Wire-Cut Mode.

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Integrated Sight Unit (ISU).

The ISU (Figure 2-6) is the primary sight unit on the Infantry Fighting/Combat Fighting Vehicle (IFC/CFV) vehicles. It is capable of sighting and tracking stationary and moving targets for the TOW, 25mm gun, and 7.62mm coaxial machine gun. The ISU is a major assembly of the TOW Subsystem and is used to track the TOW missile. In addition, the ISU provides the gunner and commander with displays of the target during both day and night operations. The ISU contains the TOW tracker, which senses the TOW infrared (IR) radiation from the IR source mounted in the missile and detects the angular displacement of the missile from the gunner's telescope line-of-sight to the target. The ISU employs a modular design concept which allows major components to be fabricated, assembled, and tested separately before being installed in the main housing. It contains the following gunner's controls:

Night sight boresight knobs. Night sight focus knob. Boresight controls. Eyepiece focus barrel.

Figure 2-6. Integrated Sight Unit.

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Day Operation.

During day operation of the ISU, (Figure 2-7) visible radiation from the target enters the day window, and is reflected by the elevation mirror to the TOW Visual Module (TVM). Here it is magnified by 12X or 4X optics (depending on the MAG switch HIGH/LOW setting). It is then passed through a set of filters which is controlled by the SENSOR SELECT switch. In "CLEAR" the light is passed through unattenuated, while in "NEUTRAL", it is attenuated to reduce an in tense input. The output of the SENSOR SELECT switch is then combined with the information displayed on the TOW reticle electronics assembly (weapon select, and range in the gun mode), and then reflected off a folding mirror upon which the TOW reticle is etched. The combined image is then fed into the DAY/NIGHT beam splitter. Here the image is combined with the gun reticle output of the reticle projector, and is then split into two paths: one going to the gunner's eyepiece and the other going to the eyepiece of the commander's relay.

Figure 2-7. Day Operation.

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Night Operations.

During night operation (Figure 2-8), IR energy (heat) enters through the night window of the periscope head assembly. The IR energy reflects off the elevation mirror to the Afocal Telescope. The Afocal Telescope focuses the IR energy on the scanner assembly in the BSA when the FOCUS knob is adjusted. The Afocal Telescope also boresights the night sight to the day sight by simply turning the NIGHT BORESIGHT elevation and azimuth knobs. The IR energy from the Afocal Telescope reflects off the scanner assembly and through the IR imager to the top of the detector/Dewar.

Changes in the temperature, due to reflected IR energy from the scanner assembly, cause the detector/Dewar to produce electrical signals. These signals pass through to the video preamplifier and video postamplifier assemblies to create a video signal output. The video signal goes to the LED array where it becomes a video display. The light from this display is focused on the back of the scanner assembly by the visual collimator and is reflected to the reticle projector. Brightness and contrast of the display are controlled in the video auxiliary control by adjusting the NIGHT VISION brightness and contrast knobs on the Unity Cover Assembly. The night image is then combined with the gun reticle produced in the reticle projector, and fed into the DAY/NIGHT beam splitter where it is split into a path going to the gunner's eyepiece and commander's relay eyepiece.

Figure 2-8. Night Operation.

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7.62mm and 25mm Gun Sighting Mode.

In the gun sighting mode of operation (Figure 2-9), the reticle provides stadia lines for finding the range of a target. After the range is found, the gunner turns the RANGE switch for the desired range. The RANGE switch sends signals to the superelevation circuit card assembly. This card assembly sends signals to the mirror drive circuit card assembly. The particular signal that is sent depends on which gun and ammunition are selected. The mirror drive circuit card assembly combines this input with input signals from the gun resolver to create a corrected mirror position signal. This signal is amplified by the power amplifier circuit card assembly and is fed into the servo motor. The servo motor positions the elevation mirror to correct for the projectile's (bullet's) line of fire.

Figure 2-9. Gun Sighting Mode.

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TOW Mode.

In the TOW mode of operation (Figure 2-10), the ISU tracks both the target and the flight of the TOW missile. The IR signal from the missile beacon on the TOW missile enters the ISU through the day window. The IR signal is reflected to the TOW Visual Module by the elevation mirror. In the TOW Visual Module, the IR signal is separated from visible light by a dichroic prism. The TOW tracker converts IR signals into electrical signals that are fed into the error detector circuit card assembly. The error detector circuit card assembly compares this signal from the TOW tracker with the signal from the center of the ISU line-of-sight and generates an error signal to guide the missile.

Figure 2-10. TOW Mode.

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Commander's Turret Controls and Indicators.

The commander's controls in the turret (Figure 2-11) consists of a weapons and turret control handle, a commander's relay, and a periscope. Indicators include slope indicators, elevation indicators, and azimuth indicators.

There is also an intercom system, a turret control box, and a weapon control box.

Commander's Hand Station.

Commander's Control Handle: The commander's control handle controls turret elevation, traverse, the 25mm cannon, the 7.62mm coaxial machine gun, and the TOW. The commander's control handle overrides the gunner's control handles when the palm switch is squeezed, if the TOW is not in flight.

Palm switch: The palm switch activates turret drive (elevation and traverse) and releases the turret drive brakes. The palm switch arms the trigger switch.

Fast turret switch: The fast turret switch increases the speed of turret traverse and weapon elevation.

Trigger switch: The trigger switch fires the 25mm cannon, the 7.62mm coaxial machine gun, or the TOW.

Drift button: The drift button reduces drift in the turret stabilization system.

Figure 2-11. Controls and Indicators.

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Commander's Integrated Sight Unit (ISU).

The commander's relay assembly (Figure 2-12) is attached to the right side of the ISU, this assembly contains prisms and lenses to extend the gunner's image to the commander's eyepiece. The commander's relay assembly provides an image identical to that seen by the gunner when viewing the commander's eyepiece. This module is separately sealed and is attached by bolts to the roof of the turret and to the ISU.

The only control on the commander's relay of the ISU is the focus barrel. The focus barrel adjusts the focus of the reticle in the field view through the commander's eyepiece.

Figure 2-12. Commander's Integrated Sight Unit.

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Commander's Turret Control Box.

The controls and indicators (Figure 2-13) of the commander's turret controlbox are described below:

Turret Power Switch and Indicator Light . The turret power switch turns the turret power on or off. The indicator light goes on when the power is on.

Turret Drive System Switch and Indicator Light . The turret drive system switch powers turret traverse and elevation of the TOW launcher, 25mm cannon, and 7.62mm machine gun. The indicator light goes on when the power is on.

Stab Switch and Indicator Light . The stab switch turns on the stabilization drive for turret drive and elevation. The stab switch maintains the turret on target while the vehicle is turning or climbing. When the indicator light goes on, the turret and gun are ready to operate in the stabilized mode.

Fan-Lamp Test Switch . The fan-lamp test switch, when in the fan position, normally turns on the gun fans. When in the center position, the gun fans automatically turn on when the gun fires. When in the lamp position, all indicator lights in the turret go on to check the bulbs.

TOW Abort Switch . The TOW abort switch causes the TOW missile wire to be cut so the missile aborts.

Figure 2-13. Commander's Turret Control Box.

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Weapon Control Box Controls and Indicators.

The controls and indicators for the weapon control box (Figure 2-14) aredescribed below:

Sear Indicator Light . The sear indicator light indicates that the 25mm gun bolt is in the sear position. The blinking indicator light indicates that the 25mm gun bolt is in the misfire position.

Arm-Safe-Reset Switch and Indicator Light . The arm-safe-reset switch selects arm and safe positions for the 25mm cannon, the 7.62 coaxial machine gun, and the TOW. The reset position will clear all weapons selected. The indicator light goes on when a weapon is armed.

Misfire Button . The misfire button brings the 25mm gun bolt back to the sear position after the trigger is pressed when the 25mm gun misfires.

PNL Light Dimmer Knob . The PNL light dimmer knob adjusts the panel lights on the weapon control box from bright to dim to off.

7.62 Button and Indicator Light . The 7.62 button selects the 7.62mm coaxial machine gun firing mode. The indicator light goes on when the 7.62mm coaxial machine gun is selected.

LO AMMO OVRD Button . The L AMMO OVRD button allows the 25mm cannon or the 7.62 coaxial machine gun to fire remaining ammunition after the LO AMMO indicator light flashes.

LO AMMO Indicator Light . The LO AMMO indicator light starts flashing and the 25mm cannon or the 7.62mm coaxial machine gun stops firing when the end of the belt passes the sensors on the ammunition can. The LO AMMO indicator light stays on when the LO AMMO OVRD button is pressed.

Grenade Launcher Switch and indicator Light . The grenade launcher switch selects power on or off to the smoke grenade launcher. The indicator light goes on when the smoke grenade launcher is armed.

Trigger Button and Indicator Light . The trigger button fires all eight smoke grenades. The indicator light goes on when the trigger button is pressed.

AP SS Button and Indicator Light . The AP SS button selects the 25mm AP single shot mode. The indicator light goes on when AP SS is selected.

AP LO Button and Indicator Light . The AP LO button selects the 25mm low rate of fire (about 100 rounds per minute). The indicator light goes on when the AP LO is selected.

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AP HI Button and Indicator Light . The AP HI button selects the 25mm AP high rate of fire (about 200 rounds per minute). The indicator light goes on when the AP HI is selected.

HE SS Button and Indicator Light . The HE SS button selects the 25mm HE single shot mode. The indicator light goes on when the HE SS is selected.

HE LO Button and Indicator Light . The HE LO button selects the 25mm HE low rate of fire (about 100 rounds per minute). The indicator light goes on when HE LO is selected.

HE HI Button and Indicator Light . The HE HI button selects the 25mm HE high rate of fire (about 200 rounds per minute). The indicator light goes on when the HE HI is selected.

Figure 2-14. Weapon Control Box Controls and Indicators.

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TOW Control Box Controls and Indicators.

The controls and indicators for the TOW control box (Figure 2-15) are described below.

Launcher UP-DN Switch and Indicator Light . The launcher UP-DN switch raises or lowers the TOW missile launcher when the palm switches on the commander's or the gunner's control handles are squeezed. The indicator light goes on when the launcher is in the raised position.

TOW Button and Indicator Light . The TOW button selects the TOW missile firing mode. The indicator light goes on when the TOW mode is activated.

Missile Tube 1 and 2 Buttons and Indicator Lights . The missile tube 1 and 2 buttons select TOW missile launcher tube 1 or 2 for firing. The indicator light goes on when its tube is selected and flashes when the tube is empty.

TOW Test Button and Indicator Light . The indicator light goes on for 12 seconds when the TOW test button is pressed. The indicator light goes off when the test is done.

TRCKR . Annunciator light on indicates a malfunction in the TOW tracking system.

CGE . Annunciator light on indicates a malfunction in the command guidance electronics system.

PWR SUP . Annunciator light on indicates a malfunction in the power supply of the TOW missile system.

Figure 2-15. TOW Control Box Controls and Indicators.

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Gunner's Turret Controls and Indicators.

The gunner's controls in the turret (Figure 2-16) include control handles, levers, and handwheels for manual or power operation of the turret and its weapons. Control boxes, indicator lights, slope indicators, elevation indicators, azimuth indicators, and a floor switch for communications are used. The controls and indicators for the gunner's hand station are described below:

Gunner's Control Handles . The gunner's control handles control traversing of turret and elevation of the weapon system.

Trigger Switches . The trigger switches fire the 25mm cannon, the 7.62mm coaxial machine gun, or the TOW missile.

Fast Turret Switch . The fast turret switch increases the speed of turret traverse and weapon elevation.

Palm Switches . The palm switches activate turret drive and release drive brakes.

Drift Button . The drift button reduces drive in the turret stabilization system.

Figure 2-16. Gunner's Turret Controls and Indicators.

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Annunciator Box Indicators.

The indicators for the annunciator box (Figure 2-17) are described below.

TOW CKT OPEN . Annunciator light on indicates a malfunction in the TOW electrical system.

OPEN HATCH . Annunciator light on indicates that the driver's hatch or the cargo hatch is open.

25 FDR MALF . Annunciator light on indicates a malfunction in the 25mm gun feeder.

MANUAL DRIVE . Annunciator light indicates a select lever is in the manual mode.

AMMO SW REVERSE . Annunciator light indicates AP and HE ammunition switches are reversed.

NO FIRE ZONE . Annunciator light on indicates that the weapons, if fired, are in a position that could damage the vehicle. Triggers do not work if the annunciator light is on.

25mm GUN MALF . Annunciator light on indicates that the misfire protection system is malfunctioning.

DRIVE MALF . Annunciator light on indicates drive system malfunctioning.

Figure 2-17. Annunciator Box Indicators.

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Turret Shield Door.

A metal shield surrounds the turret (Figure 2-18). The shield keeps the turret swing-area free of obstructions. It also gives the crew members safe access from the rear of the vehicle to the driver's station. In addition, it holds stowage items, such as a Light Anti-Tank Weapon (LAW) rocket, an M60 machine gun, and an M16A1 rifle. The shield has a sliding door facing the rear of the turret that can be opened from inside or outside. The door should be closed when the turret is moving under power.

Figure 2-18. Turret Shield Door.

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Turret Travel Lock.

A turret travel lock (Figure 2-19), locks the turret in position when engaged and unlocks it when disengaged. The turret travel lock's linkage and gear mechanism can lock the turret in a stationary position. It can also prevent turret rotation when the azimuth drive is in action. During TSS maintenance, the shield door is open. This creates a safety hazard. The turret travel lock should always be engaged before TSS maintenance is performed.

Figure 2-19. Turret Travel Lock.

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Hatch Interlock Override Switch.

The hatch interlock override switch (Figure 2-20) allows the turret to operate in combat situations if the cargo hatch switch or driver's hatch switch fails. During TSS maintenance, the hatch interlock override switch is used to allow the turret to operate while the hatches are open. During normal operation of the turret, the hatch interlock override switch is off.

Figure 2-20. Hatch Interlock Override Switch.

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LESSON TWO

Practice Exercise



1. What is the position of the launcher assembly in the ready mode?

A. Stowed.B. Raised.C. Prefire.D. Wire-cut.

2. In the commander's hand station, what controls turret traverse and elevation?

A. Drift button.B. Trigger switch.C. Fast turret switch.D. Palm switch.

3. What item provides safety from accidental azimuth movements of the turret?

A. Turret override switch.B. Turret travel lock.C. Turret traverse lever.D. Sensor select switch.

4. Which switch on the gunner's control handle activates and releases the turret drive brakes?

A. Drift switch.B. Palm switch.C. Fast turret switch.D. Trigger switch.

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5. You are checking the TOW Subsystem, and the tracker annunciator light illuminates on the TOW control box. What does this mean?

A. Power to the integrated sight unit is off.B. Power to the night sight is off.C. There is a malfunction in the TOW tracking system.D. Infrared beacon from the missile is not being detected.

6. What switch allows the turret to operate when the hatches are open?

A. Turret travel lock switch.B. Palm switch.C. Trigger switch.D. Hatch interlock-override switch.

7. Which control box contains the arm-safe-reset switch?

A. TOW control box.B. Turret control box.C. Weapon control box.D. Annunciator box.

8. What box controls the launcher in elevation?

A. Weapon.B. TOW.C. Annunciator.D. Turret control.

9. What is indicated when the NO FIRE zone illuminates on the annunciator box indicators?

A. The weapon, if fired could damage the vehicle.B. The TOW missile will not fire.C. The 25mm cannon has a misfire.D. The drive system is malfunctioning.

10. When firing a TOW missile, what is the final mode of operation?

A. Ready.B. In-flight.C. Prefire.D. Wire-cut.

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LESSON TWO

PRACTICE EXERCISE



1. B. Raised.

The launcher is in the raised position when it is in the ready mode. (Page 16, Para 1.)

2. D. Palm switch.

The palm switch controls turret traverse and elevation in the commander's hand station. (Page 25, Para. 3.)

3. B. Turret travel lock.

The turret travel lock prevents accidental azimuth movement of the turret. (Page 34, Para. 1.)

4. B. Palm switch.

The turret drive brakes are controlled on the gunner's control handle by the palm switch. (Page 31, Figure 2-16.)

5. C. There is a malfunction in the TOW tracking system.

When the tracker annunciator light illuminates, there is a malfunction in the TOW tracking system. (Page 30, Figure 2-15.)

6. D. Hatch interlock-override switch.

The hatch interlock-override switch will allow the turret to operate with the hatches open. (Page 35, Para. 1.)

7. C. Weapon control box.

The arm-safe-reset switch is located in the weapon control box. (Page 29, Figure 2-14.)

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8. B. Tow control box.

The launcher is controlled in elevation by the TOW control box. (Page 30, Figure 2-15.)

9. A. The weapon, if fired, could damage the vehicle.

With the NO Fire zone light illuminated, to fire the weapons could damage the vehicle. (Page 32, Figure 2-17.)

10. D. Wire-cut.

The final mode of the weapon system after firing a TOW missile is the wire-cut mode. (Page 19, Para. 1.)

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LESSON THREE

TOW SUBSYSTEM OPERATION.


OVERVIEW

TASK DESCRIPTION:


LEARNING OBJECTIVE:

ACTIONS: When you have completed this lesson, you should be able to identify the purpose and function of the TOW subsystem assemblies of the Bradley Fighting Vehicle.


STANDARDS: You will identify the purpose and function of the Tow subsystem assemblies of the Bradley Fighting Vehicle in accordance with the information contained in this subcourse booklet.

REFERENCES: The material contained in this lesson was derived from the following publication:

TM 9-1425-474-34-1.

INTRODUCTION

The TOW Subsystem (TSS) contains the necessary assemblies to fire and control the weapons assigned to the Bradley Fighting Vehicle. This lesson will cover only those assemblies that the 27E repairers need to know in order to perform the required Direct Support Maintenance on the TOW Subsystem.

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Basic TOW Block Diagram.

The TOW block diagram (Figure 3-1) shows the interface of the TOW subsystem assemblies. In guiding a TOW missile flight trajectory, the primary output signals are proportional to the missiles offset from the line-of-sight. All the weapons are aimed by a day/night telescope sighting system.

Launcher Assembly. The TOW missile launcher is designed to carry two missiles. It is mounted on the BFVS turret and thus follows the ISU line-of-sight in azimuth. The turret provides an elevation servo to position the launcher to follow the ISU elevation line-of-sight over the range of + 20 degrees.

Command Guidance Electronics (CGE). The CGE provides steering information to the TOW missile during flight. It also provides control for the squib firing circuits, timing and buffering circuits, and built-in test (BIT) circuitry.

Integrated Sight Unit (ISU). The ISU provides the primary sight functions for the M2/M3 vehicles. It provides day and night capabilities and accurately tracks and guides the TOW missile to the target in conjunction with the CGE and launcher assembly. It also acquires and tracks stationary or moving ground targets for the 25mm cannon and the 7.62mm coaxial machine gun.

Power Control Unit (PCU). The PCU is a sealed , ruggedized electronic assembly which interfaces between and supplies various DC and AC power forms to the fire control units of both the TOW and the 25mm cannon.

Distribution Box. The distribution box routes selected signals and voltages from the turret to the associated assemblies.

Vehicle Power. +24 VDC is provided by the Bradley Fighting Vehicle System.

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Figure 3-1. Basic TOW Block Diagram.

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Command Guidance Electronics (CGE).

The CGE (Figure 3-2) provides guidance signals for the TOW missile. It is easily accessible within the turret, and each circuit card can be maintained independently. The CGE is located under the turret floor panel in the forward left hand side of the turret. It contains seven circuit assemblies (A1 thru A7) which interact to provide guidance signals for the missile. Each circuit card assembly is held in place by two captive screws and can be easily removed and installed.

The CGE has four connectors, 2J301, 2J02, 2303, and 2J04. Connector 2J01 is a 39-pin connector that connects to the 2W102 cable. The 2W102 cable carries information from the BFVS distribution box to the CGE. Connector 2302 is a 32-pin connector that connects to the 2W103 cable. The 2W103 cable carries power from the PCU to the CGE. Connector 2J03 is a 41-pin connector that connects the launcher assembly to the CGE through the 2W104 cable. Connector 2J04 is a 55-pin connector that provides test access to all seven Printed Wiring Boards (PWB's) within the CGE.

Figure 3-2. Command Guidance Electronics.

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The CGE (Figure 3-3) contains seven circuit card assemblies that interact to provide guidance signals for the missile. Each circuit card assembly can be easily removed and installed.

Output Circuit Card Assembly A1 : Receives azimuth and elevation missile position signals as input and encodes them into signals to the missile.

Yaw Circuit Card Assembly A2 : Receives missile azimuth position signals from the error detectors of the ISU, and generates corrected missile azimuth position signals for the Output Circuit Assembly A1.

Pitch Circuit Card Assembly A3 : Receives missile elevation position signals from error detector circuits of the ISU, and generates corrected missile elevation position signals for the Output Circuit Assembly A1.

CG-Bias and CVAC Circuit Card Assembly A4 : G-Bias provides elevation signals to correct for the pull of gravity on the missile. CVAC provides signals to control the steering actuator on the missile.

Programmer Circuit Card Assembly A5 : Provides a timing sequence for events which occur during missile firing.

BIT Circuit Card Assembly A6 : Automatically tests the performance of most CGE and error detector circuitry before the missile can be fired.

Squib Circuit Card Assembly A7 : Performs the prefire, which energizes missile batteries and electronics, firing the missile and wire-cut, which terminates guidance to the missile

Figure 3-3. CGE Circuit Cards.

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Integrated Sight Unit.

The ISU (Figure 3-4) is located inside the turret directly in front of the gunner to provide the gunner with an around-the-clock sighting system. The entire turret moves in azimuth while the mirror in the ISU moves in elevation. This allows the gunner to control the ISU while tracking a target using the gunner's or commander's turret hand controls. The ISU employs a modular design concept that allows major components to be repaired and tested separately before being installed in the main housing. The day sight and night sight of the ISU provide a means of acquiring and tracking stationary or moving targets. It displays ranging information for accurate firing of the 25mm cannon, the 25mm coaxial machine gun, and the TOW, while keeping the commander, the gunner, and the other soldiers under armor. The night sight unit uses super-cooled circuits. A day/night viewer moves with the weapon, when a soldier is sighting and arming. An ISU unity window allows the location of a target in daylight for tracking with the ISU. Select switches allow controlled day and night viewing. Select switches also allow aiming with the use of reticle displays. Reticle displays indicate which weapon, range, and ammunition have been selected. Boresight controls and kits help to boresight the guns and the TOW launcher. The controls and indicators of the ISU are described below.

Night Boresight Knobs . The night boresight knobs are used by the gunner to boresight the BSA before night operations.

Commander's Relay . The commander's relay allows the commander and the gunner to view the same picture.

TOW Boresight Control . The TOW boresight control is used by the gunner to adjust the screen when in the TOW mode.

Gun Boresight Controls . The gun boresight controls are used to adjust the gun reticle in azimuth and elevation when in the gun mode.

Gunner's Eyepiece/Focus Barrel . The gunner's eyepiece/focus barrel is used to adjust the focus of the reticle in the gunner's eyepiece.

Night Sight Focus Knob . The night sight focus knob is used to adjust azimuth and elevation of the gun reticle.

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Major Assemblies of the Integrated Sight Unit (ISU).

Periscope Head Assembly. Afocal Telescope Assembly. TOW Visual Module. Main Housing. Basic Sight Assembly. Reticle Projector. Unit Cover Assembly. Error Detector Card. Superelevation Card. Unity Cover Assembly.


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Subassemblies of the Integrated Sight Unit.

Basic Sight Assembly (BSA).

The Basic Sight Assembly (Figure 3-6) is located inside the right portion of the ISU. The BSA, along with the afocal telescope, provides the night sight capabilities of the ISU. The BSA is a passive device that receives the infrared radiation from a target, and converts the infrared radiation into electrical signals and then to visible image for the observer.

IR energy enters the night window on the periscope head where it is reflected off the pointing mirror down into the afocal telescope. The focused IR energy then goes to the Basic Sight Unit (BSA) where the IR image is first transformed into video signals and then to visible light. The visible image is then passed on to the reticle projector and to the gunner's and commander's eyepieces.

Figure 3-6. Basic Sight Assembly BSA.

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Commander's Relay Assembly.

The commander's relay assembly (Figure 3-7) is attached to the right side of the ISU. This assembly contains prisms and lenses to extend the gunner's image to the commander's eyepiece.

Figure 3-7. Commander's Relay Assembly.

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Periscope Head Assembly.

The periscope head assembly (Figure 3-8) is located on the top of the ISU. The periscope head assembly has two windows, one for day vision and the other for night use. Light or infrared radiation goes through the window and is reflected by an elevation mirror downward into the main housing of the ISU. The periscope head assembly contains the elevation pointing mirror and the visible and IR windows housed in a cast aluminum structure. The integrated sight elevation mirror movement is servo controlled. The mirror drive circuit card assembly and power amplifier assembly, located in the side of the periscope head assembly, control the movement of the elevation mirror. Inputs are from the superelevation circuit card assembly, the TOW and gun resolvers, and the boresight potentiometers which control the position of the elevation mirror.

The three modes of operation for the elevation mirror are:

Operational Mode . The operational mode is the powered mode of operation.

Manual Mode . Manual mode is used to control the elevation of the mirror in the event of power failure.

Pinned Mode . The pinned mode of operation is to give a rigid elevation lock position during transportation.

Figure 3-8. Periscope Head Assembly.

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TOW Visual Module (TVM).

The TVM (Figure 3-9) is located inside the left side of the ISU. The TVM provides a two field-of-view telescope to allow the gunner to detect and track targets. The wide field-of-view (WFOV), which is used for target acquisition, has a four-power telescope magnification. The narrow field-of-view (NFOV) which is used for target tracking during TOW firings has a twelve power telescope magnification. The ISU has a magnification switch on the front panel to allow the gunner to select the desired field-of-view. The tracker assembly, which is an integral part of the module, utilizes many of the optical elements used by the twelve-power telescope. The TOW IR tracker is an integral part of the TOW visual module and utilizes many of the optical elements that are used by the visual twelve power telescope.

Figure 3-9. TOW Visual Module.

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Afocal Telescope Assembly.

The afocal telescope assembly (Figure 3-10) consists of five lenses that magnify and focus the IR image. Magnification is manually selected using the MAC select knob on the unity cover assembly. A microswitch in the TVM is switched to either X4 or X12 to control a relay that controls the 115 vrms (volt root mean square) 400 Hz applied to a motor, which switches the magnification lenses in the afocal telescope assembly. Switching time between X4 (LO) and X12 (HI) is less than a second. Two microswitches are limit switches, cutting off the power to the motor when the correct lens is in proper position.

Figure 3-10. Afocal Telescope Assembly.

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Reticle Projector.

The reticle projector (Figure 3-11) displays images in the gunner's and commander's eyepiece. The images displayed are the TOW reticle and gun cross hairs used to pinpoint a target when firing. The reticle is used to aline the weapon on target. Stadia lines are provided to determine range. Reticle brightness adjustments for the reticle are on the ISU unity cover. The magnification are manually selectable by means of the MAG switch on the ISU unity cover.

Figure 3-11. Reticle Projector.

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Superelevation Card.

The major function of the superelevation card (Figure 3-12) is to control the superelevation of the 25mm cannon and the 7.62mm coaxial machine gun. The required superelevation angle is adjusted using a 16-position rotary switch (range knob) located on the unity cover. The dial starts at 0 meters and goes to 3,000 meters in 200-meter steps. The decoder logic decodes the range position selected on the dial to determine the superelevation angle. The superelevation angle is determined by the range select control.

Figure 3-12. Superelevation Card.

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Launcher Assembly.

The launcher assembly (Figure 3-13) consists of two identical launcher tubes. Each tube contains tracks that guide the missile container. Each missile is inserted into the rear of the launcher tube. An actuating handle locks the missile in place. A TOW is selected, which activates the linear actuator that drives the actuator mechanism. The actuator mechanism is made up of a series of cams and pins that are connected to the Remote Armament Controls (RACs). There are two RACs, one on top of each launcher tube. These RACs, along with the other components, push down or raise the umbilical connector that mates with the missile. In case of power failure, the umbilical connector can be raised or lowered using the manual override. The current limiter limits the current going to the launcher. The current limiter is currently being phased out of use. An electrical motor driven actuator, when energized, drives the launcher RAC to an armed position. The detent plunger in the RAC drives the missile holdback (shear) pin from the high shear position to the low shear position. The launcher-to-missile umbilical connector is driven to mate the electrical interface to the missile. When the gunner selects a missile, the interface between the launcher and the CGE is completed to the missile. The missile receives signals via the launcher. The launcher-to-missile interface is made through a missile container 20-pin umbilical connector.

Figure 3-13. Launcher Assembly.

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Power Control Unit.

The PCU (Figure 3-14) is a sealed electronic assembly that interfaces between the ISU and the CGE. It supplies various AC and DC power forms to the fire control units of both the TOW and the 25mm cannon. It is housed in a separate box located near the distribution box. The PCU consists of switching regulator assembly (A1), converter assembly (A2), linear regulator I assembly (A3), linear regulator II assembly (A4), AC generator (A5) and EMI filter assembly (A6). The PCU connects and supplies various kinds of AC and DC voltages to the ISU, the CGE, and other fire control components. The PCU's operation is continually monitored by BIT, and any BIT failure is displayed on the TOW control box panel. The PCU has built-in overvoltage, undervoltage and overcurrent protection.

Figure 3-14. Power Control Unit.

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LESSON THREE

Practice Exercise



1. Which circuit card in the CGE provides timing sequences for missile firing?

A. Output circuit card A1.B. Yaw circuit card A2.C. Pitch circuit card A3.D. Programmer circuit and assembly AS.

2. Which ISU subassembly detects the IR signal from the missile?

A. TOW visual module.B. Basic sight assembly.C. Error detection card.D. Periscope head assembly.

3. What switch gives inputs to the superelevation card?

A. Boresight control.B. Boresight knobs.C. Commander's relay.D. Range select control.

4. How many circuit cards are in the CGE?

A. 2B. 3C. 5D. 7

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5. Which circuit card assembly in the Command Guidance Electronics provides elevation signals to correct for pull of gravity on the TOW missile?

A. Squib circuit card assembly A7.B. Programmer circuit card assembly A5.C. G-bias and CVAC circuit card assembly A4.D. Output circuit card assembly A1.

6. What connector provides test access to the printed wiring boards (PWBs) within the Command Guidance Assembly?

A. 2J01.B. 2J02.C. 2J03.D. 2J04.

7. What controls the elevation point of the mirror in the periscope head?

A. TOW visual moduleB. Superelevation card.C. Afocal telescope assembly.D. Mirror drive card.

8. What signals are provided to the distribution box from the command Guidance Electronics?

A. Missile select and missile present.B. Signal arm and trigger.C. Built-in test signals.D. Arm, fire and guidance signal.

9. Which circuit card automatically checks the performance of the Command Guidance Electronics ^Assembly?

A. Programmer circuit card.B. Squib circuit card.C. BIT circuit card.D. Output circuit card.

10. Which assembly in the ISU controls the magnification of the afocal telescope?

A. Basic sight assembly.B. Afocal telescope assembly.C. TOW visual module.D. Reticle projector.

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LESSON THREE

PRACTICE EXERCISE



1. D. Programmer circuit card assembly A5.

The programmer circuit card provides timing signals for events which occur during missile firing. (Page 44, Figure 3-3.)

2. A. TOW visual module.

The TOW IR tracker is an integral part of the TOW visual module (Page 51, Para. 1.)

3. D. Range select control.

The superelevation angle is adjusted by means of a 16 position range select control located on the front of the ISU. (Page 54, Para 1.)

4. D. 7.

The Command Guidance Electronics Assembly contains 7 circuit card assemblies A1 thru A7. Page 43, Para 1.)

5. C. G-bias and CVAC circuit card assembly.

G-bias and CVAC circuit card assembly provide elevation signals to correct for the pull of gravity on the missile. (Page 44, Figure 3-3)

6. D. 2J04.

2J04 is a 55 pin connector that provides test access to all seven PWB's within the CGE. (Page 43, Para 2.)

7. D. Mirror card drive.

The mirror drive card and amplifier located in the side of the periscope head assembly control the movement of the elevation mirror. (Page 50, Para. 1.)

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8. A. Missile select and missile present.

Missile select and missile present are sent to the distribution box from the Command Guidance Electronics. (Page 42, Figure 3-1.)

9. C. BIT circuit card.

The BIT circuit card (A6) automatically tests the performance of the CGE assembly. (Page 44, Figure 3-3.)

10. C. TOW visual module.

A microswitch in the TVM is switched to either X4 or X12 to control the magnification lenses in the afocal telescope assembly. (Page 52, Para. 1.)

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LESSON FOUR

TOW SUBSYSTEM SUPPORT EQUIPMENT.


OVERVIEW

TASK DESCRIPTION:


LEARNING OBJECTIVE :

ACTIONS: When you have completed this lesson, you should be able to identify the purpose and function of the TOW Subsystem Support Equipment.


STANDARDS: You will identify the purpose and function of the Tow Subsystem Test Set (TSS-TS), Basic Sight Assembly Support Equipment (BSA-SE) and the Alinement Breakout Box (ABOB) in accordance with the information contained in this subcourse.


TM 9-4935-474-14.

INTRODUCTION

The TOW Subsystem Support Equipment provides the means for automatic testing, alinement and fault isolation of the TOW Subsystem. This lesson covers the Support Equipment and its uses required to perform direct support maintenance on the TOW Subsystem.

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The TOW Subsystem Support Equipment (TSS-SE)(Figure 4-1) consists of TOW Subsystem Test Set (TSS-TS), Basic Sight Assembly Support Equipment (BSA-SE), and the Alinement Breakout Box (ABOB).


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TOW Subsystem Test Set (TSS-TS).

The TSS-TS (Figure 4-2) provides on-vehicle testing and fault isolation of the TSS. It consists of the Test Controller (TC), the Day/Night Sight Collimator (D/NSC), the Missile Simulator (MS) and a set of interconnection cables. The TSS-TS is completely portable, with the TC, D/NSC, MS and cables protected in three transit cases when not in use. TSS-TS units are modular in construction for ease of fault isolation and repair when necessary.

The TSS-TS subassemblies interface with the turret, the TSS units and each other through five cables and the launcher umbilical as shown in figure 4-2.

Figure 4-2. TSS-TS Block Diagram.

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Test Controller (TC).

The TC (Figure 4-3) is used with the D/NSC and MS to provide automatic verification testing and fault isolation of the TSS. It is a computer based unit that provides stimuli required for testing the TSS. It processes and measures TSS, signals, and controls the D/NSC and MS. The TC continuously monitors the status of the D/NSC and MS, and has self test capabilities. The TC front panel has a keyboard for entering data and operating commands. An alphanumeric display reads out all keyboard entries, test status messages, and special operator instructions. Indicators on the front panel indicate TC, D/NSC and MS power supply status. The front panel has operating instructions for the test set printed on flip cards. These cards are tab indexed for ready reference and are made of material to withstand the field environment. Testing is done by choosing a test program from the TC memory. Each test program consists of a logical sequence of steps which test a major equipment function or subassembly. Each test program can be executed without prior setup and contains at least one measurement that is compared with preset limits to determine a pass or fail condition. The TC is protected by a rugged transit case capable of withstanding harsh physical surroundings, such as rough handling, water, dust, pressure and temperature extremes. The top cover of the TC transit case provides storage for the TC interconnection cables. The controls and indicators are shown in Figure 4-3.

D/NSC Indicator . The D/NSC indicator lights to indicate that power is applied to the D/NSC.

MS Indicator . The MS indicator lights to indicate that power is applied to the MS.

Keyboard . The keyboard allows the operator to input data and instructions to the TC. The TC keyboard is described in 1-6 below.

1. HLT Key. The HLT key stops program execution and returns the TC to the ready state.

2. RUN Key. The RUN key causes the program to execute continuously to the end of the program, unless a failure occurs or operator intervention is required.

3. STP Key. The STP key causes the program to advance one step, pause, and display the results each time the key is pressed.

4. ENT Key. The ENT key allows the operator to enter the test data shown on the display or continues execution.

5. RPT Key. The RPT key causes the program step to repeat continuously and to display the results, with a one-second delay between repeats, until the RUN or HLT key is pressed.

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6. 0 Through 9 Keys. The 0 through 9 keys are used to enter numerical data, such as test program numbers.

Display . The display displays a maximum 24-character alphanumeric readout.

Operation Cards . The operation cards contain operating instructions for the test set.

J1 PWR Jack . The J1 PWR jack receives +24-volt power for unit operation through cable W1.

J2 Turret Jack . The J2 turret provides connection to the turret electronics through cable W2.

J3 TSS Jack . The J3 TSS jack provides connection to the ISU and the CGE through cable W3.

J4 D/NSC Jack . The J4 D/NSC Jack provides connection to the D/NSC through cable W4.

J5 MS Jack . The MS Jack provides connection to the MS through cable W5.

Test Jack . The test Jack provides connection to the alinement. breakout box for maintenance purposes.

Figure 4-3. Test Controller.

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Test Controller Circuit Cards.

The TC (Figure 4-4) contains circuit cards A1 through A17. These 17 assemblies provide the stimuli and measurement control and display functions. Signal shorting card A1 has logic circuitry and relays to allow measurement channels to be selected and shorted to ground under test program control. Signal selection and switching cards A2 through A8, under test program control, route stimuli signals from the TC stimuli generation circuitry to the test interfaces, and route all TSS/turret signals requiring measurements from the test interface connectors to the TC measurement circuitry. Three types of signal selection and switching cards are used--A, B, and C. Cards A2, A4, A5, A6, and A7 are type A. These cards can interchange with each other. Card A8 is type B and card A3 is type C. All three types function similarly.

Digital voltmeter card A9 measures AC and DC voltages required by the test programs. Operating ranges of 2, 20, and 200 volts full-scale are available by attenuating the inputs of the 2-volt range basic digital voltmeter circuitry by 10X or 100X as required. The digital voltmeter can measure voltages down to 1 millivolt and to accuracies within 0.5 percent for DC signals and 2 percent for AC signals. Analog stimuli card A10 provides DC stimuli up to ±10 volts and AC stimuli up to 20 volts peak-to-peak at frequencies from 20 to 1,000 Hz to perform various tests under program control. This card also has a 1-milliamp fixed current source and provides certain logic commands to the TSS. A precision +10-volt source is also included for use by the digital voltmeter function.

Analog processor card A11 detects, measures, and demodulates test signals, and provides certain analog stimuli signals to the TSS as required by the test program. MS and D/NSC interface card A12, under microprocessor control, supplies control signals to the MS and the D/NSC, and monitors MS and D/NSC BIT status and MS squib simulator status signals. This card is functionally divided into two sections, one each for the MS and the D/NSC. In each section, a peripheral interface adapter (PIA) circuit converts data and control inputs from the processor circuitry into control words for the MS or the D/NSC, which are inverted or buffered as required.

Programmer interface card A13 monitors the timing signals from -he TSS programmer and BIT output signals from various TSS circuits for correct levels and timing. If the levels or timing of these signals are incorrect a program interrupt signal, under microprocessor control, is sent to the TSS-TS programmer. Interface buffer card A14 provides data bus buffers to handle loading requirements of the interface ports for the PIAs on the various circuit cards in the TC. Processor card A15 provides an eight-bit integrated circuit microprocessor with an internal clock oscillator.

Each of the program memory cards A16 and A17 is capable of providing 16,384 bytes of read-only memory (ROM) for storage of the test programs. These cards also include priority interrupt circuitry for control of the timer, keyboard, and display functions.

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The timing and demodulation card A1 receives wire commands from the TSS via the launcher and power supply. It converts these commands to pitch and yaw signals that are sent to the TC and back to the TSS. The pitch and yaw circuitry on this card is self-tested, using AC stimuli from the TC. The squib simulator and BIT card A2 receive the decoded MS control signals from the TC. Control signals from the TC are four-bit digital words that control the squib simulator circuitry on the A2 card and pitch and yaw discriminator function on the A1 card. Power for the MS is provided by the DC-to-DC power supply that receives +24 volts from the TC through the W5 cable. The DC-to-DC power supply has three power supply modules that convert +24 volts received from the TC to +5, +10, and ±15 volts used by the MS circuitry. The power supply also functions as an interface between the MS and the launcher and has prefire, fire, and wire-cutter relays that are controlled by, and provide outputs to, the A2 card. The MS W5 cable is located in the transit case lid. This cable goes from the MS to the TC. The J5 Jack provides the connections.

Figure 4-4. Test Controller Block Diagram.

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Day/Night Sight Collimator.

The D/NSC (Figure 4-5) provides all optical stimuli and targets required for TSS testing. The D/NSC is mounted on the front of the ISU during testing and is powered and controlled by the TC. Target sources in the D/NSC are mounted in a movable tilt stage assembly that allows target positioning in azimuth and elevation. Control of target positioning is normally done by the operator using the Remote Position Control (RPC); however, for some tests, target positioning is controlled automatically by the TC. The D/NSC produces visual and thermal target patterns for testing the day and night vision capabilities of the ISU, and modulated IR targets for testing the TOW missile tracking functions of the TSS. When not in use, the D/NSC is protected by a rugged transit case that also stores the D/NSC interconnection cable and RPC.

Figure 4-5. Day/Night Sight Collimator.

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The optical assembly consists of an electronics assembly, a day sight (DS) target assembly, a night sight (KS) target assembly, and optics for generation of target images. It has two optical sections, one for the day sight and one for the night sight. The DS and NS target assemblies generate test target images based on the outputs from the electronics assembly. The DS target assembly produces visual target images using an array of light emitting diodes (LEDs). It also produces the modulated IR targets to simulate the TOW missile, using an array of IR LEDs. The NS target assembly produces thermal target images using a heater element controlled to a precise temperature above ambient temperature by the electronics assembly. All target images are collimated by special optics and transmitted to the ISU through windows in the tilt stage assembly. The electronics assembly, under the control of the TC, powers and controls target sources in both the DS and NS target assemblies. The electronics assembly has two circuit card assemblies, the IR/LED control card A2 and the BIT and E-target compensation card A3. The A2 card, based on control words from the TC, provides target inputs to the DS target assembly and controls the A3 card. The A3 card monitors IR target signals from the A2 card and provides BIT status outputs to the TC. The A3 card also monitors and controls the temperature of the target source in the NS target assembly.

Figure 4-6. Day/Night Sight Collimator Block Diagram.

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Missile Simulator.

The MS (Figure 4-7) consists of the missile simulator itself, the transit case, and the W5 cable. It is installed in the TOW launcher assembly to simulate TOW missile functions during TSS testing. The MS fits in either launcher tube and mates mechanically with the launcher's locking mechanism and electrically with the umbilical connector. The MS is under the control of the TC. The MS simulates the TOW missile squib and pitch and yaw discriminator functions. It also reports squib and BIT status to the TC. The MS does not simulate the weight of the TOW.

MS circuitry is contained on two printed circuit board (PCB) assemblies, A1 and A2. A1 provides timing and demodulation functions, and A2 provides control, squib simulator, and BIT functions.

Figure 4-7. Missile Simulator.

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Basic Sight Assembly Support Equipment.

The BSA-SE supplies the necessary power and control functions to operate the BSA unit during test and repair operations. It is used by the missile maintenance company to test and fault isolate the BSA. The BSA-SE is also used for retesting of the BSA to verify operation integrity. The BSA-SE components include the BSA holding fixture (BSA-HF), the rail assembly, and the BSA controller (BSAC). The An/TAM-3A test set is used in conjunction with the Basic Sight Support Equipment to provide the necessary IR targets for testing and alining the basic sight assembly.

Figure 4-8. Basic Sight Assembly Support Equipment.

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Basic Sight Assembly Holding Fixture.

The BSA-HF (Figure 4-9) holds the BSA unit being tested and provides the necessary optics for BSA testing. It is supplied with a reference mirror and an auto-collimator that are used for checking the alinement of the BSA-HF prior to use. In addition, there is a fighting vehicle system (FVS) eyepiece that may be installed in place of the microscope assembly for viewing the entire raster of the BSA unit under test. The BSA-HF and accessories are stored in a transit case when not in use. The controls and indicators for the BSA-HF are described below.

Figure 4-9. BSA Holding Fixture.

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Rail Assembly.

The rail assembly (Figure 4-10) provides a reference mounting plane for the BSA-HF and the AN/TAM-3 collimator, which are secured with clamping hardware. The rail assembly may be permanently mounted to a workbench in the ICSS and the NSMF.

Figure 4-10. Rail Assembly.

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BSA Controller.

The BSAC (Figure 4-11) is powered by 115 VAC that is converted by power supply circuitry into +5, +7, and +10 volts for BSA power. This power is sent to the BSA through relays controlled by the BSA power switch. The BSAC also supplies +17.5 volts for cryogenic power, which is controlled by the cryo switch. An adjustable voltage source provides an additional +2 volts for LED illumination. Testing is performed using the test select and sign select switches, which connect signals to be measured to the voltmeter test points. Control of the BSA display functions is provided by the LED switch, the white hot/black hot switch, the brightness control, and the contrast control. The interconnection cables are stored in the lid of the case. The controls and indicators for the BSAC are described below:

Test Select Switch . The test select switch, when in position A, allows the measurement of output voltages to the BSA unit under test at the voltmeter test points, as selected by the signal select switch. When the switch is in position B, it allows measurement at voltmeter test points of voltage drop across the signal select switch resistors per the signal select switch setting. This provides an indication of current flow to the BSA unit under test. Positions C and D are no longer used.

Signal Select Switch . The signal select switch connects DC supply voltages sent to the BSA unit under test to voltmeter "+" test point as follows:

Position 1: -10 voltsPosition 2: -7 voltsPosition 3: -5 voltPosition 4: +5 voltsPosition 5: +7 voltsPosition 6: +10 voltsPosition 7: +17.5 voltsPosition 8: ground

Voltmeter Test Points . The voltmeter test points provide connection to external voltmeter to measure signals as selected by the test set and signal switches. Signal applied to "-" test point is controlled by the test select switch, and signal applied to "+" test point is controlled by the select switch.

115-VAC Jack . The 115-VAC jack receives 115 VAC for unit operation through the power cable.

BSA Jack . The BSA Jack provides connection to the BSA unit under test through the BSA test cable.

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AC PWR Switch . The AC PWR switch applies 115 VAC to the DC power supply when in the on position. When it is in the off position, all power is removed from the BSAC.

AC Power On Indicator . When in the on position, the AC power on indicator lights to indicate that 115 VAC is applied to the BSAC.

LED Switch . The LED switch, when in the on position, turns on the display in the BSA unit under test. When in the off position, the display is turned off.

Cryo Switch . The cryo switch applies +17.5-volt power to the BSA cryogenic cooler. When it is in the off position, all power is removed from the BSA cryogenic cooler.

Cryo Ready Indicator . The cryo ready indicator is no longer used.

White Hot/Black Hot Switch . The white hot/black hot switch selects the display polarity of the BSA unit under test.

BSA Switch . The BSA switch applies +5, +7 and +10-volt power to the BSA under test, when in the on position. When it is in the off position all power is removed from the BSA under test.

2-VDC Outputs . The 2-VDC outputs provide adjustable 2-volt source for LED illumination.

2-VDC ADJ Control . The 2-VDC adjust control adjusts the voltage level available at the 2-VDC outputs.

Self-Test D Control . The self-test D control is no longer used.

Contrast Control . The contrast control adjusts the display contrast of the BSA unit under test.

Brightness Control . The brightness control adjusts the display bright-ness of the BSA unit under test.

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Figure 4-11. BSA Controller.

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Alinement Breakout Box.

The ABOB (Figure 4-12) provides test points and a connector that allow test access to missile umbilical signals and certain internal signals of the TC. It also provides connectors that receive cables from the TC when the cable continuity test is performed. Other than test points, connectors, and internal wiring, the only electrical components in the ABOB are several resistors and the TC signal switch that selects TC signals to be measured at the output and common test points. The controls and indicators for the ABOB are described below:

TC Signals Switch . The TC signals switch selects one of ten outputs of TC for direct access at the output test point when plug P7 is connected to the TC Jack test.

Output Test Point . The output test point provides access to the TC signals as selected by the TC signal switch. This test point is used with the COM test point.

COM Test Point . The COM test point is the same as the output test point.

DVM Output . The DVM output provides access to the TC timing signals when plug P7 is connected to the TC jack test.

Umbilical Access Test Points . The umbilical access test points provide access to the umbilical Signals when plug P7 is connected to the MS jack test.

Plug P7 . Plug P7 connects to the MS jack to receive umbilical signals or to the TC jack J7 to receive TC signals.

Cable Jacks . The cable jacks receive cables from the TC for performing cable continuity test 91. The cable Jacks are: D/NSC J1 jack, CGE 2J04, ISU 1J04 Jack, turret J4 jack, and MS J1 jack.

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Figure 4-12. Alinement Breakout Box.

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TOW Subsystem Support Equipment Maintenance.

To ensure that the equipment remains in ready condition, it is important that certain Preventive Maintenance Checks and Services (PMCS) be performed regularly. Systematic performance of these tasks will help keep the equipment in good operating condition and allow defects to be discovered and corrected before they result in serious damage or failure.

A series of tests is performed to isolate malfunctions in the TSSTS to one of its three assemblies and then to a replaceable subassembly. Self test (Test 00) is used to troubleshoot to the assembly level of the test set. If one or more assemblies are malfunctioning, the self test will identify them. Once the faulty assembly is identified, the operator is instructed to perform the appropriate test to troubleshoot to the responsible subassembly.

Test options include the following tests:

Test 90 is the TC fault isolation procedure. It is used to check out all signal paths, stimuli generation and measurement accurate within the TC. Test 90 can direct the operator to either alinement procedures or replacement of subassemblies.

Test 91 is the cable fault isolation procedure. It is used to troubleshoot cables W2 through W5 and W11. It is essentially the same test as the second portion of test 90; however, all communication between the TC and ABOB is through the W2 through W5 cables. Therefore, any failures can be traced to a defective cable.

Test 97 is the D/NSC fault isolation procedure. It is used to fault isolate four functional areas to the D/NSC:

PowerDay Sight CollimatorNight Sight CollimatorTilt Stage

Test 98 is used to fault isolate five functional areas of the MS:

PowerSquib SimulatorsPitch DemodulationYaw DemodulationMissile present/Gone

Before each use, the alinement of the BSA-HF with the AN/TAM-3 thermal collimator should be checked. This is to be done before the BSA unit to be tested is installed on the BSAHF. If the BSAHF is found to be out of alinement, it must be returned to depot for repair.

The BSAC is also checked before use to ensure that all necessary voltages are present. If any voltage is missing, fault isolation procedures must be performed.

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Maintenance Procedures.

The TSS-SE (Figure 4-13) provides a reliable service under a wide range of environmental conditions if recommended operating and preventive maintenance procedures are followed. To ensure that the equipment remains in ready condition, it is important that certain Preventive Maintenance Checks and Services (PMCS) and fault isolation tests be performed. PMCS are performed to help keep the TSS-SE in good operating condition and allow defects to be discovered and corrected before they result in serious damage or failure.

The PMCS are given in the table on the next page for the TSS-SE. (Figure 4-14) During PMCS, visual inspections are made on the TSS-SE. After the visual inspection, a self-test is conducted to ensure that the TSS-TS is operational. If a certain assembly in the TSS-TS is called out as faulty during the self-test, the problem must be fault isolated by running the 180-day test. The 180-day test consists of test 90, test controller fault isolation; test 91, cable fault isolation; test 97, day/night sight collimator fault isolation; and test 98, missile simulator fault isolation. After the faulty assembly has been repaired, a self-test must be run to ensure that the TSS-TS is operational.

Figure 4-13. Maintenance Support Equipment.

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Figure 4-14. Preventive Maintenance Checks And Services (PMCS)

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Self-Test.

The self-test for the TSS-TS (Figure 4-15) is conducted by activating the TC keyboard. The self-test is activated automatically when the power is turned on and is completed in about 30 to 50 seconds. It can also be activated by entering 00 on the TC keyboard and pressing the RUN key. The self-test consists of 54 steps. The first 30 steps check all logic, signal generation, and measurement capabilities of the TC. This is the highest priority of the self-test failures, and results in an immediate 'TC fail self-test" message displayed on the TC screen. The next 14 steps deal with MS power forms and signal generation. A failure in this section of the self-test will not cause an immediate failure message, and the test will continue to completion. At the end of the self-test, the message "MS fail self-test" is displayed. The last 10 steps of the self-test check the D/NSC power forms, temperature sensing lines, driver operations, and target presence. As in the previous 16 steps, the self-test will run all the way to the end before the D/NSC failure message "DNSC fail self-test" is displayed. If both the MS and D/NSC fail, the message "MS/DNSC fail self-test" is displayed. The message "DNSC temp not ready" may be displayed. This indicates that the temperature circuits in the D/NSC have not reached operating temperature, although the remainder of the D/NSC circuits have passed the self-test. This is conditional ready message. When the HLT key is pressed on the TC keyboard, the message ready is displayed. The TSS-TS is now operational, and the TSS-TS functional test procedure can be completed. After waiting about 5 minutes for the D/NSC to reach operation temperature, the self-test should be run again. If the TSS-TS passes the self-test, the message "ready" is displayed.

Figure 4-15. TOW Subsystem Test Set.

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BSAC Self-Test.

The BSAC (Figure 4-16) self-test is conducted by performing the following procedures:

1. Check to ensure that all switches on the BSAC are in the off position.

2. Connect the BSAC power cable between the 115-VAC jack and 115 volt 60 hertz single power source.

3. Set the AC power, the BSA, and the cryo switches to the on position.

4. Connect the voltmeter across voltmeter test points.

5. Set the test select switch to position A.

6. Set the signal select switch to positions 1 through 7, one at a time, and measure voltage at the voltmeter test points. The voltage should be as follows:

Normal Indication Signal SelectVolts DC Switch Position

-10.2 to -9.8 1-7.14 to 6.86 2-5.1 to -4.9 35.145 to 5.355 46.86 to 7.14 59.8 to 10.2 617.15 to 17.85 7

If the voltage at switch position 7 is out of tolerance, replace the 17.5-V power supply PSI. If the voltage at switch positions 1 through 6 is out of tolerance, replace multivoltage power supply PS2.

7. Adjust the 2-VDC, ADJ control while measuring voltage at the 2.-VC test points, and verify that voltage can be adjusted from less-than or equal-to 2 VDC to greater-than or equal-to 5.5 VDC.

8. Set the BSA switch and the cryo switch to the off position.

The BSA-HF is checked by performing the BSA-HF alinement procedures. The BSA-HF alinement procedures will not be covered in the subcourse.

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Figure 4-16. Basic Sight Assembly Controller (BSAC).

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Test 90.

Test 90, the TC fault isolation procedure (Figure 4-17) is used to check out all signal paths, stimuli generation, and measurement accuracy within the TC. The test consists of two sections. The first section is the first 30 steps of self-test in a stop-on-fail format. The second part is a continuity check of switching circuit paths within the TC, also in a stop-on-fail format. To activate test 90, enter "90" on the TC keyboard and press the RUN key. The message 'connect wraparound cable" will be displayed. After connecting the wraparound cable, press the ENT key. Test 90 takes about 90 seconds to complete when no failures are encountered. A failure is identified by the test number, step number, and circuit card(s) failed. When a failure is detected, pressing the RUN key on the TC keyboard allows the test program to continue to the next failure, or if no other failure occurs, to completion. Each failure must be corrected in the order of its occurrence. After alining or replacing the indicated circuit card(s), repeat test 90 to verify that the fault has been corrected.

Figure 4-17. Test 90.

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Test 91.

Test 91, the cable fault isolation procedures (Figure 4-18), is used to troubleshoot the W2 through W5 cables. Test 91 is essentially the same test as the second portion of test 90; however, all communication between the TC and the ABOB is through the W2 through W5 cables. Therefore, any failures can be traced to a defective cable. To initiate this test, enter "91" on the keyboard and press the RUN key. The message "connect breakout box" will be displayed. After the cable and the ABOB have been connected, press the ENT key. If the cables pass the test, the message "test 91 completed" will be displayed. If one or more cables fail the test, the TC screen will display: "91: xxx fail wx..." (xxx represents the step failed; x represents the cable to be fault isolated). Repeat test 91 after replacing or repairing the cable to verify that the fault has been corrected. Test 91 does not check power cable W1. However, a separate continuity check of power cable W1 can be performed to verify its performance.

Figure 4-18. Cable Fault Isolation.

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Test 97.

Test 97, the D/NSC fault-isolation procedure (Figure 4-19 thru 4-22), is used to fault isolate the following four functional areas of the D/NSC: power, day sight collimator, night sight collimator, and tilt stage. Step 1 of test 97 contains all the fault isolation routines in test 97 to check the operation of the two collimators, their associated cards, and the power. The next six steps, steps 2 through 7, check the visibility of the day sight collimator targets, using an IR viewer. If in any step the target is not visible, the optical assembly must be replaced. Step 8 of test 97 allows the operator to control the tilt stage with the RPC manually. By listening to the motors and looking at the movement. of the tilt stage, the operator can ensure that the tilt stage motors and the RPC are operating properly. To perform this test, the D/NSC must be connected to the TC through the W4 cable, and power must be applied to the TC. To initiate test 97 enter "97" on the TC keyboard and press the RUN key. The TC screen will display "test 97:xxx in progress" (where xxx equals the step number). At the end of step 1, the TC screen will either display "test 97:001 passed" or "test 97:001, replace" assemblies as indicated on the TC screen. If the first step passes, the operator must press the STP or RUN key to progress to each of the following steps. If the first step fails, the operator must respond to the failure displayed on the TC screen. A target pattern of the D/NSC is shown in Figure 4-23. The repairer uses this target pattern during the checks or troubleshooting procedures.

Figure 4-19. Day/Night Sight Collimator Fault Isolation.

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Test 97 Continued.


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Test 97 Continued.


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Test 97 Continued.


Figure 4-23 Day/Night Sight Collimator Target Pattern.

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Test 98.

Test 98, the MS fault-isolation procedure (Figure 4-24 thru 4-26), is used to fault isolate the following five functional areas of the MS: power, squib simulators, pitch demodulation, yaw demodulation, and missile present/gone. The first six steps of the test 98 MS fault-isolation procedure consist of BITs. These BITs check the power forms and signal generation circuitry in the MS. The next eight steps ensure that the signals generated by the MS fall within specified parameters. The last two steps are manual continuity checks that verify the operation of relays on the A2 card. To perform this test, the MS must be connected to the TC through W5 cable, and power must be applied to the TC. To initiate test 98, enter "98" on the TC keyboard and press the RUN key. The TC screen will display "test 98:xxx in progress" (where xxx equals the step number). The program will continue through step 14 even if one of the steps fails. When step 14 is completed, the display indicates whether the entire test passed or failed. If the test failed, the fault isolation for all the steps is displayed. If a failure is indicated, press the HLT key, enter "98," and press the STP key. Pressing the STP key after each step will cause test 98 to proceed step-by-step and display a pass or fail message after each of the first 14 steps. In the STP (step) or run mode of operation, the TC screen will display "in progress" for steps 15 and 16. If one of the first six steps fail, the A1 card must be replaced. If a failure occurs during steps 7 through 14, the MS alinement procedure must be attempted before any cards are replaced. At the end of the test sequence, the TC screen will display "98:014 passed" if the MS has successfully passed all the steps.

Figure 4-24. Missile Simulator Fault Isolation.

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Test 98 Continued.


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Test 98 Continued.


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LESSON FOUR

Practice Exercise



1. What are the three main components of the BSA-SE?

A. TSS-TS, BSA-TE, and ABOB assembly.B. D/NSC, TSS-TS, and ABOB assembly.C. BSAC, BSAHF, and rail assembly.D. TSS-TS, MS, and D/NSC assembly.

2. What is the purpose of the alinement breakout box?

A. To test, aline and fault isolate the TOW subsystem.B. To test the test controller.C. To aline the D/NSC.D. To test the missile simulator.

3. How many circuit cards are located within the missile simulator?

A. 7B. 5C. 4D. 2

4. What test is performed to fault isolate the cables?

A. Test 90.B. Test 91.C. Test 97.D. Test 98.

5. Which circuit card makes all the voltage measurements inside the test controller?

A. A2.B. AS.C. A6.D. A9.

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6. Which test controller circuit cards are interchangeable?

A. A2, A4, A5, A6, and A7.B. A8, A2, A1, A9, and A12.C. A12, A13, A14, A15, and A17.D. A8, A9, A10, A11, and A12.

7. In what two ways can the D/NSC targets be positioned?

A. Remote position control and test control.B. Day sight target assembly and optical assembly.C. Night sight and day sight target assembly.D. TOW target signals and thermal target signals.

8. What provides targets used during BSA testing and alinement?

A. AN/TAM-3A test set.B. Missile simulator.C. Day/night sight collimator.D. Test collimator.

9. What test troubleshoots to the subassembly level of the TSS-TS?

A. Test 90.B. Test 92.C. Test 94.D. Test 98.

10. What two cards in the optical assembly provide IR/LED control and BIT?

A. A1 and A2.B. A2 and A3.C. A3 and A1.D. A1 and LED control.

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LESSON FOUR

PRACTICE EXERCISE



1. C. BSAC, BSAHF, and rail assembly.

The three main components of the BSA-SE are, BSA controller, BSA holding fixture, and the rail assembly.(Page 72, Figure 4-8.)

2. B. To test the test controller.

The ABOB provides test points and a connector to allow test access to missile umbilical signals and internal signals of the test controller. (Page 78, Para. 1.)

3. D. 2.

The missile simulator circuitry is contained on two printed circuit boards. PCB assemblies A1 and A2. (Page 71, Para. 1.)

4. B. Test 91.

Test 91, the cable fault isolation procedure is used to troubleshoot the W2 through W5 cables. (Page 80, Para. 1.)

5. D. A9.

Digital voltmeter card A9 measures AC and DC voltage required by the test programs. (Page 67, Para. 2.)

6. A. A2, A4, A5, A6, and A7.

Three types of signal selection and switching cards are used. Card A2, A4, A5, A6, and A7 are type A. These cards can enter-change with each other. (Page 67, Para. 1.)

7. A. Remote position control and test control.

Control of the target positioning is manually done by the operator using remote. position control (RPC); however, for some tests, target positioning is controlled automatically by the TC. (Page 69, Para. 1)

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8. A. AN/TAM-3A test set.

The AN/TAM-3A test set is used in conjunction with the Basic Sight Support Equipment to provide IR targets for testing and alining the basic sight assembly. (Page 72, Para. 1.)

9. A. Test 90.

Test 90 can direct the operator to either alinement procedure or replacement of subassemblies. (Page 80, Para. 3.)

10. B. A2 and A3.

The electronic assembly has two circuit assemblies, the IR/LED control card A2 and the BIT and E-target compensation card A3.(Page 70, Para. 1.)

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LESSON FIVE

BRADLEY FIGHTING VEHICLE MAINTENANCE CONCEPT

Soldier's Manual Task 093-411-3910

OVERVIEW

TASK DESCRIPTION :

Direct maintenance on the TOW Bradley Fighting Vehicle System and Support Equipment.

LEARNING OBJECTIVE:

ACTIONS: When you have completed this lesson, you should be able to identify the maintenance concept of the TOW Bradley Fighting Vehicle System and support equipment.


STANDARDS: You will identify the TOW Bradley Fighting Vehicle maintenance concept in accordance with the information contained in this subcourse book.


TM 9-4935-474-14.

INTRODUCTION

Maintenance is performed on the Bradley Fighting Vehicle TOW Subsystem in two methods, on vehicle and off vehicle. This lesson outlines the responsibilities of each level of maintenance.

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TOW Bradley Fighting Vehicle Maintenance Concept.

The TOW Bradley Fighting Vehicle maintenance structure consists of unit (organization), intermediate (DS/GS), and depot maintenance. A general description of unit, intermediate, and depot maintenance follows.

Unit Maintenance.

Unit maintenance (Figure 5-1) is the responsibility of and is performed by the using organization on its assigned equipment. The mission of unit missile maintenance is to perform visual inspection and the confidence test of the TOW Subsystem.

Figure 5-1. Maintenance Flow Chart.

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Simplified Test Equipment (STE-M1/FVS) Fault Message.

The turret mechanic 45T uses the STE-M1/FVS to troubleshoot the turret. The STE-M1/FVS may find a fault in the TOW subsystem and display a fault message. The turret mechanic notes the fault number and notifies the TOW/DRAGON repairer 27E.

The 27E TOW/DRAGON repairer will use the STE FAULT NUMBER INDEX in section III, page 3-5, of TM 9-1425-474-34-1 to find the initiating procedure to start troubleshooting. (Figure 5-2)

Figure 5-2. Simplified Test.

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On-Vehicle Troubleshooting (DS/GS).

The on-vehicle troubleshooting (Figure 5-3) is performed when a fault is found in the TOW Subsystem. Faults are found by the following four ways:

Visual inspection. Simplified Test Equipment fault message. 180 Day Verification Test fault message. Confidence Test fault message.

The 180 Day Verification Test is performed every 180 days to ensure that the TOW Subsystem installed in the BFVS is in proper operation condition. The 180 Day Verification Test will enter pass or give fault or operator messages. The operator message requires the performance of follow-on procedures before the test can be continued. The fault message indicates a fault and the follow-on procedure must be performed to correct the fault. Once the indicated repair or replace action has been performed, the test procedures where the fault message first appeared must be rerun. If the fault has been corrected, the test will pass. The 180 Day Verification Test is accomplished by the 27E TOW/Dragon contact team.

The Contact Support Set (Figure 5-3) is used by the contact team to perform on-vehicle maintenance.

Figure 5-3. Contact Support Set.

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The 180-Day Verification Test.

In order to launch a missile properly and score a direct hit, the TSS must operate correctly in all phases. To accomplish this mission, a 180-day verification test is performed whenever the subsystem assemblies are replaced or repaired and as outlined in the PMCS.

The 180-day verification test is actually a combination of seven tests. Within each of the seven tests there are several different steps. Some of these steps are performed automatically by the test controller; and others require manual input from the operator. In normal ambient temperature (72 degrees F), it takes about 10 minutes cool-down time. The average time to complete the 180-day verification test is 50 minutes. Add 30 minutes for cabling up and running the self-test on the TSS-TS.

Hookup Procedures.

To perform the 180-day verification test, the cables should be hooked up to the BFVS as follows:

Cable W1 from the TC to the turret power connector. Cable W2 from the TC to the turret connector. Cable W3 from the TC to the CGE and the ISU connectors. Cable W4 from the TC to the D/NSC. RPC cable from the D/NSC into the turret compartment. Cable W5 from the TC to the MS. Cable W11 from the TC to the MS.

Once all the cables are connected, the hookup procedures are completed.

Self-Test Procedures.

After the hookup procedures are completed, the next pretest preparation is to perform the self-test procedures of the TSS-TS. The self-test is performed by first turning on the power to the turret, the turret drive, and the BSA. Move the MAG switch to high and set the sensor select knob to clear on the ISU. Raise the TOW launcher and select TOW on the TOW control box. Once this is done, punch in "97: 8 run" on the TC keyboard. This will display the TOW reticle and the D/NSC reticle. Using the gunner's hand station, aline the two reticles. Then using the RPC, move the D/NSC reticle in elevation and azimuth until it reaches the thick part of the TOW reticle at all four directions. Once this is completed and the D/NSC reticle is back to center of the TOW reticle, the self-test alinement procedures are completed.

After the self-test is completed, the 180-day verification test may be run. The first step is to enter "1" on the TC keyboard and press the RUN button. This allows the 180-day verification test to start and run automatically

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until an error is found or the TC tells the operator to perform a manual function. The flashing "C" means that the ENT button on the TC keyboard must be pressed before the test will start again. A flashing "O" means that once the operator performs the function, the 180-day verification test will start again automatically. An example of "0" may read "0 Select TOW." The seven tests of the 180-day verification are described below.

Test 1. Test one checks out the preconditions of the turret. This test has nine steps, five of which are performed automatically and four that require a short period of time to perform.

Test 2. Test two is testing the power control unit in the turret. This test has 13 steps.

Test 3. Test three is testing the command guidance electronics. This test has 13 steps. In this test, there are two steps that require several minutes to perform.

Test 4. Test four is testing the interface between the CGE and the TOW launcher. This test has 11 steps. During this test, you would be required to remove the MS from tube one and two.

Test 5. Test five is testing the TOW visual module. This test has seven steps.

Test 6. Test six is testing the night sight. This test has only one step that requires approximately 9 minutes to perform.

Test 7. Test seven is testing the mirror servo electronics displays in the ISU. This test has six steps. When tests 1 through 7 have gone through the TC and a malfunction does not show up on the display, the TC will display "test completed." This signifies that the TOW subsystem 180-day verification has been completed.

The 180-day verification test is part of the on-vehicle maintenance and is performed by the 27E contact team. Faults in the system are found by the following four ways:

Visual inspection. Simplified test equipment checks. 180-day verification checks. Confidence test.

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180 Day Verification Test Fault Message.

The TOW/DRAGON repairer 27E runs the verification tests of the TSS on the vehicle every 180 days. The 180 day verification test will either pass the TSS or give you fault or operator messages. The operator message requires you to perform a follow-on procedure before the test will continue. The fault message indicates a fault and you perform the follow-on procedure to correct the fault.

Once you have performed the indicated replace or repair action, rerun the test procedure where the fault message first appeared. If you have corrected the fault, the test will pass (Figure 5-4).

Figure 5-4. 180-Day Test Fault Message

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Off-Vehicle Maintenance of the BFVS TOW Subsystem.

Off-vehicle troubleshooting is performed when a fault is isolated to the Basic Sight Assembly (BSA) or the Unity Cover. If a BSA is returned to the maintenance facility, BSA test procedures are performed to isolate the malfunction to a faulty subassembly or an alinement procedure. BSA test procedures are performed using Basic Sight Assembly Support Equipment (BSASE) in the Night Sight Maintenance Facility.

If the Unity Cover is returned to a maintenance facility, Unity Cover test procedures must be performed to isolate and repair the malfunction.

The Night Sight Maintenance Facility (NSMF) (Figure 5-5) or Improved Contact Support Set (ICSS) is used to perform off-vehicle maintenance.

Figure 5-5. Night Sight Maintenance Facilities.

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Depot Maintenance.

The mission of Depot Maintenance (Figure 5-6) is to repair SRUs and return them to supply channels. At this maintenance facility, unserviceable modules, cards and boards constructed with solid state elements or a combination of solid state and conventional piece parts are repaired. All other items declared non-repairable at intermediate maintenance level are also repaired or rebuilt at depot level maintenance. Personnel at this level would maintain theater reserve stock. These personnel would have the level of training and experience to ensure continuity of operations. Depot level maintenance consists of complete repair/overhaul of optical/electronic units and assemblies to the piece part level.

The Command Guidance Electronics and launcher repair is Red River Army Depot, Texarkana, Texas for CONUS units.

The Integrated Sight Unit depot is Sacramento Army depot, Sacramento, California for CONUS units.

Mainz Army depot, Mainz, West Germany is the depot facility handling all repairs from units in Europe.

Figure 5-6. Depot Maintenance.

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LESSON FIVE

Practice Exercise



1. Off-vehicle maintenance is performed on what items of the TSS?

A. Integrated sight assembly.B. Launcher.C. Test controller.D. BSA and unity cover.

2. What cables are used to connect the turret when performing the 180-day verification?

A. W1 and W2.B. W3 and W4.C. W5 and W11.D. W2 and W11.

3. Who performs STE checks?

A. Operator.B. Gunner.C. Turret mechanic.D. Commander.

4. What assembly is tested during test No 2 of the 180-day verification test?

A. Command guidance electronic unit.B. Power control unit.C. Integrated sight unit.D. Launcher umbilical outputs.

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5. What test performs the servo electronics test during the 180-day verification?

A. 2B. 3C. 5D. 7

6. What is used to position the D/NSC reticle during self-test of the TSS-TS?

A. Remote position control.B. Gunner's hand station.C. Commander's hand station.D. Test control keyboard.

7. What is the first step in running the 180-day verification test?

A. Enter 97.8 on the test controller keyboard and press the step button.

B. Enter "90" on the test controller keyboard and press the RUN button.

C. Enter "1" on the test controller keyboard and press the RUN button.D. Enter "1" on the test controller keyboard and press the STEP

button.

8. What is the lowest level of maintenance authorized to perform the 180-day verification?

A. Organizational.B. Depot.C. DS/GS.D. Operator.

9. What level of maintenance repairs SRUs?

A. DS/GS.B. Depot.C. Organizational.D. Operator.

10. How many tests are performed during the 180-day verification test?

A. 3B. 4C. 6D. 7

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LESSON FIVE

PRACTICE EXERCISE



1. D. BSA and unity cover.

Off-vehicle troubleshooting is performed when a fault is isolated to the basic sight assembly or unity cover(Page 107, Para. 1.)

2. A. W1 and W2.

Cables used are: W1 from the TC to the turret power connector and W2 from the TC to the turret connector.(Page 104, Para. 3.)

3. C. Turret mechanic.

The turret mechanic uses the simplified test equipment to perform STE fault procedures. (Page 105, Para. 1.

4. B. Power control unit.

Test two is testing the power control unit in the turret.(Page 105, Test-2)

5 D. 7

Test seven is testing the mirror servo electronics display. in the ISU. (Page 105, Test seven.)

6. A. Remote position control.

Using the RPC moves the D/NSC reticle in elevation and azimuth until it reaches the TOW reticle at all four directions.(Page 104, Para. 4.)

7. C. Enter "1" on the test controller keyboard and press the RUN button.

The first step is to enter "1" on the TC keyboard and press the RUN button. (Page 104 Para. 5.)

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8. C. DS/GS.

The 180-day verification is performed by the contact team using the contact support set. (Page 103, Para. 2.)

9. B. Depot.

The mission of depot maintenance is to repair SRUs and return them to supply channels. (Page 108, Para. 1.)

10. D. 7

The 180-day verification is a combination of seven tests.(Page 105, Para. 2.)

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Bradley Fighting Vehicle Tow

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