Applications of Hydraulics&Pneumatics : Session 6

8/3/2019 Applications of Hydraulics&Pneumatics : Session 6

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1

Applications of

HydraulicsPneumatics

&

By: Alireza Safikhani

6

2

Actuators

Actuators

Limited-Rotary Rotary LinearcylinderHydromotorVane

Single-acting

Double acting

Shock absorber

gear

vane

piston

Piston

3 Linear Actuator: Principle of Application The hydraulic cylinder converts hydraulic energy into mechanicalenergy. It generates linear movements. For this reason, it is alsoreferred to as a linear motor.

4

Construction


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5

Applications6

Examples

7

Examples8

Type of Cylinder

Single Acting Cylinder Double Acting Cylinder


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Type of Cylinder

Single Acting Cylinder Double Acting Cylinder

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Type of Double Acting Cylinder

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Type of Double Acting Cylinder12

Type of Mounting

If the machine member moves in a straight line typeIf the machine member moves in a straight line type

motion, a fixed mount can be used.motion, a fixed mount can be used.

If the machine member is required to move in an arc aIf the machine member is required to move in an arc a

pivot mounting must be used.pivot mounting must be used.


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Mounting

Cap SquareFlange

Head Tie RodExtended

Foot SideLugs

Cap Fixed Spherical EyeCap Tie Rod ExtendedHead Trunnion

Cap-Fixed EyeHead & Cap Tie Rod ExtendedCaped Fixed Clevis

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Mounting

Head Square Flange

Cap Turn-onSide TappedIntermediate Turn-on

Cap RectangleCenterline LugsCap Rectangular Flange

Head RectangularEnd LugsHead Rectangular Flange

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Mountings

A AK B C D D

F G D M R S

SS SW UF UH UL U

US NUT

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End position cushioning

Cylinders with end position cushioning are used toCylinders with end position cushioning are used tobrake high stroke speeds. They prevent a hard impactbrake high stroke speeds. They prevent a hard impactat the end of the stroke.at the end of the stroke.

Cushioning is not required for speeds of v < 6 m/min.Cushioning is not required for speeds of v < 6 m/min.At speeds of vAt speeds of v 66--20 m/min, cushioning is achieved20 m/min, cushioning is achievedby means of restrictors or brake valves. At speeds of vby means of restrictors or brake valves. At speeds of v> 20 m/min, special cushioning or braking procedures> 20 m/min, special cushioning or braking proceduresare required.are required.


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17 Considerations Bucklinguckling Bearing Loadearing Load Cushionsushions Eccentric Loadsccentric Loads

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Seals

The function of seals is to prevent leakage losses inThe function of seals is to prevent leakage losses in

hydraulic components. Since pressure losses alsohydraulic components. Since pressure losses also

occur as a result of leakage losses, seals are ofoccur as a result of leakage losses, seals are ofconsiderable importance for the efficiency of aconsiderable importance for the efficiency of a

hydraulic system.hydraulic system.

Static seals:Static seals:

OO--rings for the cylinder housingrings for the cylinder housing

Flat seals for the oil reservoir coverFlat seals for the oil reservoir cover

Dynamic seals:Dynamic seals:

Piston and piston rod sealsPiston and piston rod seals

Rotary shaft seals on turning devicesRotary shaft seals on turning devices

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Seals

Identification of seals in a double acting adjustablecushioned cylinder

1 2 3 4 5 6

1 Cushion screw seal

2 Cushion seal

4 Piston seal5 Barrel seal6 Piston rod/wiper seal

3 Wear ring

20 Applications

1) Used in internal and external sliding surfaces2) Used for low and high pressure3) Low resistance to sliding motion

O-ring

1) Used in external sliding surfaces2) Used for low pressure3) Low resistance to sliding motion

L-ShapedPacking

1) Used in internal and external sliding surfaces2) Used for low and high pressure(Depending on pr essure, several are applied together.)3) High resistance to sliding motion

V-ShapedPacking

1) Used in internal and external sliding surfaces2) Used for low and high pressure3) Low resistance to sliding motion

U-ShapedPacking

Features / ApplicationsShapeType


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Sealing22

O' Ring piston seals

AnAnO'O'--ring piston seal is a loosering piston seal is a loose

fit in the groove, with the outerfit in the groove, with the outer

diameter just in contact with thediameter just in contact with thecylinder bore. When pressure iscylinder bore. When pressure is

applied theapplied theO'O'--ring is pushedring is pushed

sideways and outwards to sealsideways and outwards to seal

the clearance between the outerthe clearance between the outer

diameter of the piston and thediameter of the piston and the

cylinder wall.cylinder wall.

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Cup seals

Used on medium and largeUsed on medium and large

bore cylinders.bore cylinders.

Seal in one direction only.Seal in one direction only.

One for single actingOne for single acting Two for double actingTwo for double acting

Low radial exertion toLow radial exertion to

reduce the static break outreduce the static break out

frictionfriction

High complianceHigh compliance

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Z Rings

Used for piston seals onUsed for piston seals on

smaller bore cylinderssmaller bore cylinders

Seals in both directionsSeals in both directions

Take up less spaceTake up less space Z shape acts as a light radialZ shape acts as a light radial

spring providing low radialspring providing low radial

exertion and highexertion and high

compliance.compliance.


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O' Ring barrel seals

These are static sealsThese are static seals

and will be a tight fit inand will be a tight fit in

their groove locationstheir groove locations Butt joint seal for tieButt joint seal for tie

rod construction.rod construction.

Screwed barrel and endScrewed barrel and end

covercover

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Piston rod seals

One piece seal serves theOne piece seal serves the

dual role of pressure sealdual role of pressure seal

and wiper seal.and wiper seal. Outer body of the seal is aOuter body of the seal is a

pressure tight fit within thepressure tight fit within the

bearing housing.bearing housing.

Cleaning action removesCleaning action removes

abrasive particles that canabrasive particles that can

settle on the rod whensettle on the rod when

outstrokedoutstroked..

Special seal for harshSpecial seal for harsh

environmentsenvironments

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Seal Material28

Piston rod bellows

Alternative to special wiper seals, also referred to as gaiters.Alternative to special wiper seals, also referred to as gaiters.

Specify as original equipment, as the cylinder requires a slightSpecify as original equipment, as the cylinder requires a slightlyly

longer than standard piston rod.longer than standard piston rod.

Ideal solution where the out stroked piston rod is likely to beIdeal solution where the out stroked piston rod is likely to be

scratched or abraded by falling debris.scratched or abraded by falling debris.


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Wear ring

A wear ring is an open bandA wear ring is an open band

fitted around the piston.fitted around the piston.

It is made from a hardIt is made from a hardplastic material.plastic material.

In the event of a high sideIn the event of a high side

load, it becomes a bearingload, it becomes a bearing

that prevents excessivethat prevents excessive

distortion of the seals.distortion of the seals.

Protects against scoring ofProtects against scoring of

the barrel from the piston.the barrel from the piston.

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Self Compensating Units

The principle of operation is progressive flow restriction.

The piston is pushed in easily at first, oil is displaced through a large

number of graduated metering orifices. As the stroke progresses fewer and fewer metering orifices are available.

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Example

s = 0.012 m

v = 1 m/s

F=100N

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Hydro motors

Hydraulic motors are components in theHydraulic motors are components in theworking section. They areworking section. They are drivedrivecomponentscomponents (actuators).(actuators).

They convertThey convert hydraulic energyhydraulic energy intointomechanical energymechanical energy and generate rotaryand generate rotarymovements (rotary actuator).movements (rotary actuator).

If the rotary movement only covers aIf the rotary movement only covers acertain angular rangecertain angular range, the actuator is, the actuator isreferred to as areferred to as a swivel driveswivel drive..

Hydraulic motors have theHydraulic motors have the samesamecharacteristic values as pumpscharacteristic values as pumps. However,. However,

in the case of hydraulic values we speak ofin the case of hydraulic values we speak ofcapacity rather than displacement volume.capacity rather than displacement volume.


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Hydro motors34

Animation

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Animation36

Applications


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Load Lifting38

Rotary Actuators

Used for turning components, operating processUsed for turning components, operating processcontrol valves, performing a wrist action in roboticcontrol valves, performing a wrist action in robotic

applications.applications. Provide angular reciprocating rotation up to 360Provide angular reciprocating rotation up to 360oo

Rotary vane typesRotary vane types

Rack and pinion typesRack and pinion types

Chain TypesChain Types

Screw TypesScrew Types

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Rotary vane

Double acting with 270o angle of rotation

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Rotary rack and pinion

Double acting rack and pinionDouble acting rack and pinion


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Rotary rack and pinion

Double acting double torqueDouble acting double torque

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Chain Type

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Screw Type44

Power Transmission: Open Loop


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Reversible Open Loop46

Close Loop with Make UP

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Close Loop with Gravity Make UP

Applications of Hydraulics&Pneumatics : Session 6

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Transcript of Applications of Hydraulics&Pneumatics : Session 6