AE Lecture - 2
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Transcript of AE Lecture - 2
8/14/2019 AE Lecture - 2
http://slidepdf.com/reader/full/ae-lecture-2 1/44
Frames
A. Prasanna
8/14/2019 AE Lecture - 2
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Frame
The frame or under body is the main skeleton of
the vehicle.
The remaining parts of the chassis are mounted
on it.Chassis frames are made of “steel Section”
They are strong enough to withstand the load
and also light in weight to reduce dead weight onthe vehicle.
8/14/2019 AE Lecture - 2
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Location of major parts on the chassis:
The engine is mounted in the front end of the frame and is connected to the clutchand transmission unit to form a complete
power assembly.
The rear axle housing is attached throughthe real spring at the rear end of the
frame.
Contd
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The wheel and the tyre assembliessupport the frame
The steering system has some partsattached to the frame and the body
The petrol tank is fastened to therear of the frame.
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Functions of the frame
To carry the weight of the vehicle andpassenger.
To withstand the engine and transmission
torque.To bear thrust, acceleration and braking
torque.
To resist the centrifugal forces whencornering.
To withstand bending and twist
Contd
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Types of frame
Conventional frame
Semi – Integral frame
Integral or Unitized frame
The chassis frames are pressed steelmembers and are easily attached toeach other by riveting or welding.
Contd
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The frame basically consists of twolongitudinal members of mils steel with
channel section.
These two members are connected
cross - wise by cross members of tubular or box like cross section.
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Construction
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Conventional frame
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It is called as non – load carrying frame
The loads on the vehicle are transferredto the suspension by this type of frame.
The total frame is mounted on the wheelaxle by means of springs.
Mostly used in heavy vehicles like trucks.
The cross sections of the frame areusually channel, tubular or box type.
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Semi-Integral frame construction
The rubber body mountings are usuallyreplaced by relatively stiff mountings.
This arrangement transfers a part of the
frame load to the body structure also.This type is mainly used in European cars
and American cars.
This construction is heavy when comparedto the previous type.
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Integral frame construction or frameless
construction
This is also called as Chassisless, Unitary ormonocoque construction.
There is no separate frame.
This used in passenger cars.
This construction provides a stiff lightconstruction suitable for mass producedvehicles.
Contd
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All the assembly units are attached to the
body.
Heavy side members are eliminated and
cross members are combined with the floorof the body.
This type of construction led to muchreduction of weight.
Contd
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The members are welded together asone assembly.
In this type the stresses are evenlydistributed throughout the structure.
A strong structure with goodtorsional rigidity and resistance inbending is provided by this type.
Contd
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SUB FRAME
A frame is attached to the body framein the front of the body shell.
The engine and the gear box aresupported on these frames at thefront suspension using independentrear suspension.
These are simple in construction andmounted in rubber blocks.
Contd
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Front Sub-Frame
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Rear Sub-Frame
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This frame supports the main frameat three points.
This is to isolate the components from
twisting and flexing effects.
In turn protect the body from engine
vibrations.
Contd
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ADVANTAGES OF SUB - FRAMES
1. It helps to dampen the vibration.
2. It simplifies the production process while
assembling.
3. It facilitates repair, service and overhaul.
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Types of sections of frames
Channel section
This is used in long members of theframe. It is good in bending and tubular in
torsion.
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Box section
This is used in short member of theframe. It is good in bending and torsion.
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Box Type
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Tubular section
This is used in three-wheeler, scooters,matadors and pick-ups
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BACK BONE FRAME
A central longitudinal steel tube is called
back bone.The section below uses single arm parallel
type of suspension.
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The engine gear box unit is accommodated at theforked front end of the frame.
The driving shaft is made to pass through theinside of the central tubular portion of the frame.
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This frame is build up of two channelsections, which are pressed andwelded together.
This type of frame is used inindependent suspensions.
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Frame
Members
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It consists of two longitudinal or side
members A and B.These are made in the form of
pressings of channel section.
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The side members are generallyarranged to be closer at the front.
The side members are brazed by anumbers of cross members C.
Dump irons-D are provided at thefront and rear ends.
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Springs are connected to brackets ‘E’ which are provided to support therunning boards.
Brackets ‘F’ are used to support theengine, gear box, brakes shafts,…..
The frames are stiffened with cross
pressing for independent suspension andare stiffer at the front end.
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X - Frame
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The side members and cross members
are rigidly attached to each other by
riveting or welding.
Heavy side members are eliminated and
cross members are connected with the
floor of the body.
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‘X’ member may be of channel or box
section.
This type of frame imparts rigidity to the
frame.
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DEFECTS IN CHASSIS FRAME
Some of the defects are;
CracksDislocated parts Broken welds Buckling
The chassis is checked for thesedefects and suitably rectified.
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The following methods are used to prevent
rust formation;
Use of galvanized sheets.Use of zinc enriched primer paint.
Use of plastic coating on panels.
Use of rubberized solution. Avoiding tight corners so that the moisture cannot
get settled.
Providing plenty of drain holes to allow trapped
water to run out.
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It is important that the chassis frame is
properly aligned.
After repair is carried out on the frame, the
alignments should be checked with the
original measurements.
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Materials for Frame
The various tools used are Mild Sheet Steel,Carbon Sheet Steel and Sheet nickel alloy steel.
The composition of sheet nickel alloy is;
Carbon - 0.25 to 0.35 % Manganese - 0.35 to 0.75 % Silicon - 0.30 % (Max)
Nickel - 3 % Phosphorous - 0.05 % (Max) Sulphur - 0.5 % (Max)