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Chery S11 / Chery QQ. Manual - part 23

Chery QQ Service Manual Chassis System

Step

Operation

Normal outcome

Abnormal outcome

Check the liquid level of
the brake liquid inside
the oil storage tank

At normal height

Too low

Turn off the ignition

switch

Make sure the static

brake is loose

Activate the engine

The alarming indicating

light is on when the engine is
activated.

The light is on when the

engine is activated, but it
goes off after the engine is
started.

The light is not on when the

engine is activated.

The light is on after the

engine is started.

Step the brake pedal to
the extreme

The pedal moves stably

toward the floor.

The pedal stops and resists

the pressure.

The pedal moves unsteadily;

The pedal is too soft or too

close to the floor.

Release the brake pedal The pedal returns to its

original position.

The pedal fails to return to
the original position.

Test the hydraulic brake
system

The braking action is

immediately operated when the
pedal is stepped.

The operation of the brake

is smooth and normal without
any blocks and vibration of
the pedal.

The steering wheel and the

brake pedal do not vibrate
when the pedal is stepped.

The car stops without using

too much force in stepping the
pedal.

The car moves steadily

forward

during

braking

operation.

The front and rear brakes

work simultaneously.

The brake does not have much

operational noise.

The brake does not delay in

reset after the pedal is
released.

The braking action delays

after the pedal is stepped.

The brake works roughly when

the pedal is gently stepped.

The steering wheel or the

brake pedal vibrates when the
pedal is stepped.

It is hard to step the pedal

and to stop the car movement.

The car moves toward one side

when the brake is applied.

The front brake and the rear

brake work unevenly.

There is much operational

noise of the brake.

The brake delays to return to

the original position, after
the pedal is released.

To verify the outcome of the tests, make comparisons between the verified

outcomes with those of the car/system of the same model in operation.

Chery QQ Service Manual Chassis System

Refer to the related fault diagnosis table for the operational outcome.

2) External factors that have imp-

acts upon the braking performances
Tires

The differences of the contacts

with the road surface as well as the
differences  in  adhesion  forces  for
various  tires  may  lead  to  the
differences in braking performances.
Under  the  following  circumstances,
some  unfavorable  impacts  might  be
caused to the braking performance.

Difference in the sufficiency of

air filling to the tires;

Difference in tire sizes;
Differences in tire surface

patterns

Vehicle loads

Heavier duty vehicles need

larger braking forces. For the
vehicles with uneven loads, the wheel
subject to the maximum loads needs
larger braking force than the other
wheels.

Wheel positioning

The tests for the braking system

should be made on the road surface
meeting the following conditions.

3) Tests for the braking system

The tests for the braking system
should be made on the road surface
meeting the following conditions.

Dry
Clean

Properly leved

Horizontal

The tests are not to be made on

the following road surfaces, because
the tires will not evenly adhere to
the ground surface.

Wet
Slippery
Covered with soft and loose soil

If the road surface bulges, which

makes the load weight lopsided toward
the wheels on one side, unfavorable
impacts will be caused to the tests.
If the road surface is not leveled,
which makes the wheel bounce and jump,
unfavorable impacts will also be
caused to the tests.

Under different car speeds, the

tests on the braking system can be
made by way of the brake pedal forces
for  the  point  braking  and  abrupt
braking. It is advised not to apply
the brake in a steady-firm way or to
make the tires slip by towing. The
braking  distance  for  the  wheel
rotations  in  the  action  of  abrupt
braking will be shorter than the one
for the dead movement of the wheels.
Therefore, the deadly applied brake
and the slipping tires cannot truly
reflect the braking performances and
efficiency.

Unless under extreme speed

reduction, the brake system needs to
be balanced so as to avoid the hard

feelings of the brake pedal when
abrupt and dead braking action is
applied.

Chery QQ Service Manual Chassis System

4) Stroke of brake pedal

The excessively short stroke of

the brake pedal is mostly caused by
the action of the air inside the
braking system. Discharge the air
inside the system until all the air
is discharged completely. Refer to
the “Air Discharge for Hydraulic
Systems” for more details. The
reasons uncommonly seen to cause the
excessively long stroke of the brake
pedal are as follows:

Excessive tears and wears of the

friction lining

Leakage in the hydraulic system

Make regular and periodic

measurements of the brake pedal
strokes, which refer to the distances
for the pedal to move from a
completely released position to the
floor.

5). Braking liquid leakage

Leave the engine in idle running

operation and leave the transmission
shaft at the “idle gear” position.
Step on the brake pedal and keep the
stepping force unreplaced. If the
pedal is lowered slowly under the
unreplaced force, it means there
might be leakage in the hydraulic
system. Make the following visual
checks to see if there is any leakage:

Check the liquid level inside the

main pump liquid storage tank of
the braking system. Normal tears
and wears of the friction lining

will lead to the slight lowering of
the liquid level in the storage

tank. If the liquid level is too
low, it will cause the brake
alarming indication light to be on,
which means there might be
internal or external leakage for
the hydraulic system.

Check to see if there is any

leakage at the joints of the
braking pipe and the braking tube.
Check the torque of the fastening
parts or replace the oil pipe and
tube.

Check to see if the components

connecting the brake are damaged
or not. Replace the components if
needed.

Check to see if there is any

leakage at the protection cover of
the clamp and wheel cylinder. If
any, replace the parts as needed.

Chery QQ Service Manual Chassis System

II.Guide to the maintenance of hydraulic brake

1.The master pump of the braking
system

1). Refilling of the liquid storage
tank for the master braking pump

Warning: Do not fill in the liquid excessively,

which may result in the overflow of the braking

liquid to the engine or other parts of the front

cabin during the operation of the braking system.

The braking liquid is corrosive and combustible

in nature, which may cause corrosions to the

other parts and components. If it contacts with

the air exhaustion system of the engine, it might

lead to fire hazard or human injuries.

The liquid storage tank and the

master pump are connected and sealed
by  way  of  sealing  rubber  sheath,
fastened  with  screws.  The  liquid
storage tank is located at the left
side of the car and under the engine
cabin  cover.  Sufficient  level  of
braking liquid should be maintained
in  the  tank  of  the  master  pump.
Therefore, under normal conditions,
the liquid storage tank does not need
maintenance. When the braking liquid
level  inside  the  storage  tank  is
excessively  low,  the  liquid  level
sensor will make the timely alarming
signal.

Refilling of braking liquid

Clean the outer surfaces before
opening the cover of the liquid
storage tank so as to prevent the dust
from entering the tank.

Open the screwed cover
The refilled liquid should not

exceed the maximum liquid level
inside the tank

Re-install the screwed cover

2) Replacement of the liquid storage
tank of the master pump

1. Remove the wire plug of the
liquid level sensor of the storage
tank;

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