Page 496 - Foton Workshop Manual - Auman EST-M

DI - 442 Diagnosis - Mechanical fault diagnosis

Frame and suspension fault

Frame fault
Overview
1. Function of frame

It is used to support and connect each assembly of vehicle, maintain each assembly at correct position
and withstand various loads inside and outside the vehicle.
2. Requirements for the frame

a. Frame needs to have adequate strength and suitable rigidity.
b. Frame shall have the features of simple struction and light weight.
c. Frame shall reduce the center of gravity and get a bigger front steering angle as much as possible so as to
ensure the stability and steering flexibility during driving.
Precautions
1. The frame assembly is welded by carbon dioxide gas arc welding.

2. The maximum angle deviation between the upper and lower win plates and the web plate of
longeron and crossbeam is ±1°.
3. The height difference for the axial symmetr of weldin nuts shall not be more than mm..
Nut welding shall be secured. The peeling moment shall meet the requirement.
4. Welding shall be secure and reliable. The weld seam shall be smooth and even. No cold solder
joint, solder skips, slag inclusion, undercut, burnthrough, overlap, etc. welding defauts.

5. The back of frame assembly shall be painted. Painting shall be even. Slight flow mark is allowed.
Do not allow pinholes, hard spots, depaiting, exposed undercoat, etc.
6. In cold weather, preheat before welding to avoid cracks.
Failure phenomenon list

Failure phenomenon Possible reason Failure elimination
1. Run with overload for long. Run with reasonable load and at reasonable speed.
2. Fatigue crack caused by driving on a
Replace the
rough road for long time
Frame broken 3. Increase the number of plates without Keep the quantity of original design steel plates
following the regulations and specifications
4. There is original crack in the frame Welding or replace with new parts
5. Collision or turnover accident Replace the
1. The elasticity of front left and right plate When the width error is ≤ 10~15mm, replace
springs is not uniform it with qualified leaf spring.
The height difference on 2. Frame deformed seriously Adjust the frame
the left and right of driver 3. Cab support height difference too much Check and adjust
cab is too large (seen from 4. The air pressure difference in the tyres is Adjust to make the air pressure in the left and right
front) too much tyres the same
5. Tyre wearing difference too much Use the typres with small wearing difference
6. Tyre dimensions different Use the same spec tyres

DI-442