Chery A series. Manual — part 80

-- Measure the thickness of friction lining, as shown

in the figure.

Caution: The service limit is 2 mm.

-- Check the contact between the friction lining of

brake and the brake drum, as shown in the figure.

MAINTENANCE OF BRAKE WHEEL CYLINDER

-- Check the oil leakage of brake wheel cylinder, and

the damage of dust boot.

-- Detach the brake wheel cylinder, and check

whether there are some scores on piston or
cylinder wall, whether the spring is broken, and
whether the oil seal is damaged. Replace the brake
wheel cylinder if any of the above is found.

MAINTENANCE OF SPRING

-- Check the breakage, deformation or elastics

weakening of the spring, and replace it, if any.

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STRUCTURAL DIAGRAM OF REAR WHEEL DRUM BRAKE

A15LHD

adopts the non-balanced drum brake (leading trailing shoe brake) for its rear

wheels, as shown in the figure below.

Structural Diagram of Rear Wheel Drum Brake

The piston of brake wheel cylinder pushes out the brake shoe with the force of brake

fluid to rotate it outward around the contact point of the brake shoe and the support plate
when braking, and thus the friction lining of brake shoe is pressed towards the brake drum,
which creates the brake torque to brake the vehicle.

The braking pressure disappears when the braking is released, and the brake shoe

returns back to its original position with the help of the return springs 3, 4 and 11.

1 Brake back plate

9 Support plate

2 Pin shaft

10 Rivet

17 Brake shoe with wedge-shaped

adjusting plate assy.

3 Return spring

11

Lower

return

spring

18

Friction

lining

4

Brake

shoe

fixing

spring

12

Tension

spring

19 Wedge-shaped regulating plate

5 Push rod

13 Inspection hole

20 Wedge-shaped regulating block

6 Parking brake lever

14 Compression spring

7 Brake shoe assy.

15 Clamping pin

8 Support

16 Spring seat

21 Brake wheel cylinder

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The braking clearance of rear brake is adjusted automatically. In case the braking

clearance exceeds the set value due to the shoe plate wear, the wedge-shaped regulating
block 20 located between the lever and brake shoe will move downwards with the help of
spring force of tension spring 12 to compensate the clearance increase between the lever and
wedge-shaped regulating block so as to make the brake shoe further open toward the brake
drum to compensate the friction lining wear.

RELATED PARAMETERS OF VACUUM BOOSTER AND MASTER BRAKE
CYLINDER

A15LHD series vehicle’s braking equipment adopts the 228.6mm (9in) vacuum booster and
tandem type master brake cylinder, which realizes the booster effect using the vacuum
produced by the operating engine. The vacuum chamber of the booster connects to the air
intake pipe of engine via the vacuum hose and check valve.

The master brake cylinder adopts the tandem type master brake cylinder, which consists of
the cylinder body, piston, spring, spring seat, cup and etc. The master brake cylinder
connects with the front part of the booster using two bolts. A brake fluid reservoir is installed
on the upper part of master brake cylinder. Two working chambers (primary chamber and
secondary chamber) at the front and rear are connected serially in the master cylinders.

Main technical parameters of the A15LHD brake system are:

Master brake cylinder: 22.2 mm

Vacuum booster: 228.6 mm (9in)

Vacuum booster boost ratio: 3.9:1

Travel of primary chamber: 16 mm

Travel of secondary chamber: 18 mm

Diameter of wheel cylinder of front wheel disc brake: 54 mm

Outer diameter of brake disc: 256 mm

Thickness of brake disc: 13 mm

Thickness of front friction lining: 14 mm

Diameter of brake drum of rear drum brake: 200 mm

Diameter of wheel cylinder of rear drum brake: 17.46 mm

Brake shoe of rear drum brake: 200 mm×40 mm ×5 mm

Front and rear braking power distribution ratio: 65% for front wheel, and 35% for rear wheel

Parking brake: Acting force of parking braking control rod (38mm from terminal) < 400 N
when parking on a ramp, with 20% full load

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INSPECTION OF VACUUM BOOSTER

Inspection of brake performance

The driver will feel the brake pedal difficult to step down and its resistance force
considerably increase compared with normal condition when he step it after the vacuum
booster fails. In this case, the booster assy. shall be replaced in time. The condition of
vacuum booster is also determined in accordance with the following convenient method:

-- Shut down the engine, and forcefully step on the brake pedal several times to remove the

vacuum kept inside the vacuum booster.

-- Step on the brake pedal with the appropriate force to make the pedal kept in proper

position.

-- Start up the engine. If you feel the brake pedal fall down automatically and considerably

(force increase), it shows that the function of vacuum booster is normal; if the pedal is no
reaction, and nor force increase, it exhibits that the booster has failed, and the booster shall
be replaced.

-- Replace the booster assy., and, at the same time, replace the gasket. The tightening torque

of the booster assy. and master brake cylinder retaining nut is 20±2 N* m.

Inspection of the check valve of booster vacuum hose

The check valve of vacuum booster is installed in the vacuum hose. If the check valve
failure, the driver will feel the brake pedal difficult to step down, with the feeling of failure
to step it down to its limit, and the subsequent braking performance decreases evidently.

Blow the compression air in accordance with the direction of arrow on the check valve body
when inspecting the check valve, and the air is available to pass through; and don’t pass
through if blowing the air in the reverse direction. Its one-way through is also inspected
using the mouth suction method. Replace the vacuum hose assy. if the check valve is badly
sealed.

PARKING BRAKE SYSTEM

The parking brake is realized by adding a set of manual operating mechanism on the

rear wheel brake, as shown in the figure below. Due to the common use of a set of brake with
the rear wheel brake, it simplifies the structure and reduces the weight.

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