Great Wall service chassis and body Manual - part 52

BR-4

Braking System

 Notice and Troubleshooting

Troubleshooting (continued)

Trouble

  Causes

 Inspection items

There are quack-

q u a c k   n o i s e s

without using the

brake.

Alien materials such as stone is reeled inside the wheel shell

Nuts on hub is loose;

The brake pedal or vacuum booster pushrod is adjusted

improperly;

The wheel bearing is worn or damaged or lubricated

insufficiently;

(disc type brake)

The outer end edge of brake pad support plate or brake pad

is dog-eared;

The silent pad is poor in properties;

The sliding liner is worn;

The mounting bolt is loose

The piston returns incompletely

(drum type brake)

There is loose or redundant part.

Clear away the alien materials

Tighten the nut to the specified torque; and

change it in case the bolt hole is enlarged;

Check and adjust

Check, lubricate or change

Check repair or change

Check and make change according to real

situation

Check and make change according to real

situation

Check and tighten according to the necessity.

Check, repair or change

Check, take out or repair.

There is continuous

screaming noise

without using brake

The brake pedal or vacuum booster pushrod is adjusted

improperly

The vacuum booster, master cylinder or wheel-brake cylinder

returns incompletely.

(Disc type brake)

The piston is rusted or seized;

The brake pad in brake caliper locates improperly;

There is friction between the brake disc and brake caliper

shell;

The brake pad support plate is mounted improperly;

There is interference between the abrasion indicating lamp

of brake pad and the brake disc due to the brake pad

abrasion;

(Drum type brake)

The pressure spring of brake shoe is soft rigidity, damaged

or unsuitable;

There is crack on the brake bottom plate flange;

There is interference of brake bottom plate with the brake

drum after it is bending or warping.

The brake drum interferes with the brake bottom plate or

with brake shoe due to it is processed improperly;

Other brake parts

There is loose or redundant part in braking system;

The brake liner is polished due to it is adjusted over-tightly;

The wheel bearing is worn, damaged or lubricated

insufficiently.

Check and adjust

Check, repair or change

Check and add the lubricant according to

the necessity;

Repair or change

Repair or change

Repair or change

Change

Change

Repair or change

Repair or change

Change the brake drum

Check, maintain and change according to

the necessity;

Check, maintain and change according to

the necessity;

Check, maintain and change according to

the necessity;

BR-5

Braking System 

 Inspection and Adjustment

pedal push rod

braking lamp switch

pedal push-rod

free stroke of

pedal: (3-6) mm

Inspection and adjustment

Inspection on and adjustment of brake pedal

1.

Check the pedal height as shown in the drawing to

whether it is correct,

The height from the pedal to the front floor:

Dr SF

160mm

SL SK  SY  SJ 

(190-200)mm

2.

Adjust the pedal height if necessary:

(a)

Loosen the locking nuts of braking lamp switch;

(b)

Loosen the braking lamp switch to the most degree.

(c)

Loosen the locking nuts of drag rod;

(d)

Adjust the pedal height through rotating the pedal drag

rod;

(e)

Rotate the stop light switch reversibly until it contact

with the stop baffle of pedal.

(f)

Screw up the two locking nuts.

(g)

Check the braking lamp is lightened or not when tread

down the brake pedal.

(h)

Check and adjust the pedal free stroke after adjusting the

pedal height

QK Adjust the free stroke of pedal if necessary:

(a)

Loosen the locking nuts of the pedal drag rod and rotate

the pedal drag rod to adjust the pedal free stroke.

(b)

Start the engine to confirm the free stroke.

(c)

Check the pedal height after adjusting the pedal free

stroke.

3.

Inspection on Pedal Free Stroke:

(a)

Stop the engine working and tread down the brake pedal

several times until the vacuum booster is not in the stage

of vacuum.

(b)

Tread down the pedal until the resistance occurs, and

measure the distance shown in the drawing.

Pedal free stroke

(3-6)mm

pedal height

BR-6

Operation test of vacuum booster

Remark: check the operation of vacuum booster with the

vacuum booster tester if workable.

1.Operation inspection

(a)

Before starting the engine, tread down the brake pedal

several times, and check the pedal reservation distance to

ensure there is no change occurs.

(b)

Tread down the brake pedal and start the engine. If the

treaded pedals continue to move downward, which means

the operation is normal.

1.

Inspection on Air-tight

(a)

Start the engine for 1-2 min and then turn it off. Then

tread down the brake pedal slowly for several times, if the

pedal move downward continuously in the first, but

return gradually in the second or third time, which means

the vacuum booster has a good air-tight.

(b)

Tread down the brake pedal when the engine is working,

then stop the engine, but tread the pedal down. If the

reservation distance doesnít change within the 30 seconds,

which shows the air tight of vacuum booster is good.

Air-bleeding of braking system

Remark: air-bleeding is required if any operation for braking

system is conducted or the pipe line is doubted to have air.

1.

Fill the oil cup with the brake liquid

Check the liquid level of oil cup after the air in each wheel

brake pump is exhausted. If necessary, add the brake liquid.

2.

Connect the vinyl resin pipe with the vent screws.

Insert the other end of pipe into the container with half brake

liquid.

Remark: the air-bleeding shall begin from the longest pipe line

when the wheel-brake cylinder is exhausting the air.

3.

Air exhaust of the pipe line in braking system

(a)

Tread down brake pedal slowly several times.

(b)

Loosen the vent screws until the brake liquid flows out

while letting the assistant tread down the pedal. Then

screw up the vent screws.

(c)

Repeat this approach until there is no air in the liquid.

4.

Repeat the approach for the wheel-brake cylinder.

normal

abnormal

the third time

the second time

the first time

Braking System 

 Inspection and Adjustment

BR-7

Check and adjust the parking brake

1.

Check the stroke of operating lever of the parking

brake to see whether it is correct.

Drag the brake operating lever to the max stroke and count the

grooves it passes.

Stroke of operating lever of parking brake:

Dr

(9-10) Teeth

SL SK SY

(7-9) Teeth

2.

Adjust the parking brake lever where necessary:

Remark: Adjust the rear brake shoe clearance before the

adjustment.

Brake shoe clearance: 0.6mm

(a)

Loosen the locking nut and then rotate the adjustable nut

until the stroke is correct, then screw up the nuts.

(b)

The brake shoe shall not be stagnant after the adjustment.

Braking System

 Inspection and Adjustment