Page 508 - Foton Workshop Manual - Auman EST-M

DI - 454 Diagnosis - Mechanical fault diagnosis

Braking system failure

Driving brake failure
Overview
1. Function
a. The vehicle has certain energy of motion when driving at certain speed When the driving speed increases, in
order to reduce the speed or stop the vehicle, must apply a force with the direction opposite to the driving
direction. This force is called braking force. The vehicle braking system is the device generating braking force
b. The driver can control the braking force according to the situation of road and traffic to realize certain
forced braking so as to reduce the vehicle speed or stop the vehicle.
c. When driving down a slope, in order to maintain the speed of vehicle, it is necessary to use the braking
system.
2. Working principle

The braking system adopts friction braking. The wheel brake utilizes friction to brake the wheels. The friction
force between the tires and ground stops the vehicle. Therefore, the essence of braking is to convert the
vehicle dynamic to other types of energy (normally heat energy) by force, which expands to atmospheric
environment.
3. Composition

The brake system consists of air source, service brake, parking brake, wheel brake, exhaust brake and signal,
auxiliary brake.
4. Requirements for the braking system

a. Good braking performance. Including braking efficiency, stability of braking efficiency and direction
stability at braking The evaluation criteria for braking efficiency include braking distance, braking
deceleration, braking force and time. The constancy of braking efficiency refers to the ability of "heat fade"
and "water fade". The direction stability during braking means the ability of keeping original driving
direction when braking, i.e. no off tracking, no side slipping.
b. Easy to operate.
c. The braking stability is ok. The braking torque can increase rapidly and stably as well as release rapidly and
thoroughly.
Precautions
1. Make sure to place the parking brake handle at the parking position.
2. Fix the wheels with triangle wood blocks or wedge which shall be placed very close to the front and
back of tyre. It is better to fix two rear wheels.
3. When the valve body and pipeline on the brake pipeline are removed, the engine shall be shut down and
the brake pedal shall be repeatedly pressed until the reading of upper air pressure of the barometer is zero.
4. When working under the vehicle, the engine and ignition switch shall be off When replacing each part,
must pay attentions to the correct method. Otherwise, it will impact the working performance of braking
system.
5. When replacing the parts, use the parts with the same part numbers or same functions.

6. When performing service to the braking system, it is very important to keep the site and parts clean.

DI-454