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
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