JAC Trucks. Manual — part 105

42

Operation Inspection for Steering
Mechanism
1) Put front wheels on a swivel table.
2) Rotate steering wheel clockwise
and anti -clockwise to its limit posi鄄
tion, to detect if it is fluent.
3) Let engine run in idle speed and
check steering wheel for free play.
The limit value of this free play is 15~
35mm. Rotate the adjusting screw
clockwise to decrease the free play,
while rotate anti -clockwise to in鄄
crease.
4) When engine run in idle speed,
the torque of steering wheel should
be around 19.6N.
5)When staring the engine to turning
steering wheel to two sides for sever鄄
al times .When removing the air from

the engine ,then fill oil into it.
6冤Turing the steering wheel to the
front.
7冤Turn off the engine to checking oil.
If it need oil, then fill it.
Note:To checking is steering oil on a
high temperature .If it has some trou鄄
bles, then doing the 4 and 5 steps
again or mending power steering
pump.

Use and Maintenace

1冤 Check the new truck to driving for
3000要4000km ,then fill oil to steering
and cleaning oil net.
2冤 Always checking the oil measure
or oil quantity in the oil crock, if it has
something wrong that change it .
3冤 Do not disassemble the steering
system for another side .Pay atten鄄

tion to the oil pump pipeline ,it can
not fill with air in it .keep cleaning it.
Step:
a) Turn the steering out oil pump into
the steering in oil pump.
b) The return oil inlet connect with oil鄄
can inlet.
4冤 In some troubles of power steer鄄
ing, the drive can use the hand
steering but could not use for a long鄄
time.
5冤 Don't steer when parking, since it
will shorten useful life of parts.
6冤 According to the regulate to fill
hydraulic pressure oil, the environ鄄
ment temperature is above 0 益 ,
change steering system should
adopt L -HM 464# wear resistance
hydraulic pressure oil; the environ鄄

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series trucks

43

ment temperature on 0 益 . (the dif鄄
ferent number oil can't mix an us鄄
age).The import power steering or
steering pump to choose to press oil
with the DEXRONII model number
liquid.(American G.M. standard)

The use and maintenance of
power steering

1)How to use of power steering
a) Don't steer when parking for 5
minutes.
b) Forbid to steer the steering wheel
when can not moved.
c) Forbid to steer the steering wheel
in the same place.
d) Forbid to steer the steering wheel
speed for 90turn/m.

2)How to maintenance of power

steering

The main idea is to prevent ,to check
for scheduled time .Following about
the ministry of communications stan鄄
dard about the car JT 辕 T201要95叶The
arts and crafts maintenance of car曳
and city build ministry standard
CJl7要86 叶The technique condition
mending way of the city bus曳.
a)Daily maintenance: to checking the
truck when driving in order to your
security.
b)One class maintenance(2000-3000
kms)
i. Each lubrication partto fill the
grease, the power steering should be
fill the oil on time.
ii. Insure cross shaft , cross/lax pull
rodten ball end to moved vivid and
not loose.

iii. Check tight each conjunction part.
iv. Check pipe conjunction part, in鄄
sured and don't leak oil .
c)Second class maintenance(10000-
15000 kms)
i. Chang the power steering oil.
ii. Clean and check the steering
wheel.
iii. Clean the power steering oil net.
Iv Check front axle, ball axle, steer鄄
ing knuckle, steering knuckle arm,
steering knuckle frname.
v. Disassemble, length pull rod,
cleaning and checking parts in order
to insure them well.
vi.The other parts, please read the
reference. (JT 辕 T 201要95 )
d)To install steering knuckle plumb鄄
ing arm and locate blots. The daily

44

maintenance:
i. Insure the location. Find out steer鄄
ing knuckle plumbing arm is fall, then
put them on.
ii. If the steering knuckle plumbing
arm have some mistake, change the
new ones.
iii. Tight the steering gear and frame,
frame and frame blot.
iv. When turning the direction, insure
the length pull rob and steering
knuckle plumbing arm do not inter鄄
vene for each other.

渊IX冤Braking system

Braking systems of trucks of this se鄄
ries are: parking brake system(center
drum) and running brake system (air
brake, hydraulic brake)

1. Running brake system
1.1 Air brake

1) Brief description of this system:
Compared with hydraulic brake, air
brake can bring greater braking
force under the condition that force
on the pedal is not great and the
pedal stroke is not long; at the same
time, dual-circuit air-pressure driv鄄
ing braking device is equipped to
front and rear wheel separately, so
the braking is safe, reliable, labor -
saving, and more effective; even if
one of the brakes does not work, the
vehicle can still brake safely.
2) Structure and theory (referring to
the following diagram)
Brake pipeline is arranged as fol鄄
lows: compressed air produced by

air compressor 1 comes into the
main air reservoir 3 (namely wet air
reservoir); and then the air is separat鄄
ed into two and come into the front
chamber 9 of the auxiliary air reser鄄
voir and the rear chamber 4 of the
main air reservoir, the front chamber
9 of the auxiliary air reservoir and the
rear chamber 4 of the main air
reservoir. Compressed air in the front
chamber 9 of the auxiliary air reser鄄
voir and the rear chamber 4 of the
main air reservoir come into upper
and lower chambers of brake valve
8, and then the air is transported
separately to rear brake chamber 12
and front brake chamber 2. Check
valves 10 installed on ends of the air
inlet pipes of the front chamber 9 of

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series trucks

45

the auxiliary air reservoir and the rear
chamber 4 of the main air reservoir in
case that compressed air in the air
reservoir flows backwards. There are
interfaces for air pressure gauge 7
and pressure -adjusting valve 6.
When air pressure reaches 0.74 -
0.84Mpa, compressed air props up
valve of the pressure -adjusting
valve, and comes into upper cover of
the air compressor to make air inlet
valve open and the air compressor
idles. When brake valve 8 is de鄄
pressed, front and rear brake cham鄄
ber 2 and 12 operate at the same
time, which makes front and rear
brakes operate. When the brake ped鄄
al is released, compressed air in
front and rear brake chambers go in鄄

to the atmosphere by front and rear
air-deflating valves 11 and 13.

1. air compressor曰 2. front brake chamber曰 3. front cavity on main gas cylinder
4. rear cavity on main gas cylinder曰 5. safety valve曰 6. pressure control valve
7. barometer曰 8. brake valve曰 9. additional gas cylinder曰 10. one-way valve
11. front quick-release valve曰 12. rear brake valve曰 13. rear quick-release valve

Interface for air inlet

Interface for low pressure

Interface for clutch

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Brake assembly

The function of brake is to utilize
power produced by friction between
brake drum and brake shoe slice to
absorb kinetic energy of vehicle to
decelerate or stop the vehicle. Front
and rear brakes of this brake system
adopt imbalanced structure and are
mainly composed of brake chamber,
brake arm and brake

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series trucks

1. return spring locating pin曰 2. roller shaft-brake shoe
3. roller-brake shoe曰 4. gripping ring-brake shoe roller
shaft曰 5/18. front brake shoe with liner assembly曰

6/19. front brake friction plate曰 7. brake cam曰 8. front brake baseboard with liner assembly曰 9. front brake dust cap曰

10. hex bolt曰 11. front brake air chamber support frame with liner assembly曰 12. front left brake air chamber assembly曰
13. hex bolt曰 14. front brake adjusting arm assembly曰 15. shoe shaft fixed bolt曰 16. front brake shoe-shoe shaft曰

17. front and rear brake shoe shaft-liner曰 18. return spring

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Adjusting arm

1冤Lubrication: mount oil month on
adjusting arm, use lithium base
grease periodically to lubricate ad鄄
justing arm (maximum lubrication in鄄
terval is limited to 10000km), or else,
life of adjusting arm will decrease.
2冤Check adjusting arm's counter鄄
clockwise force moment periodically:
rotate adjusting nut of adjusting arm
counterclockwise when running every
20000km and measure whether the
rotary moment is bigger than 18Nm,
measure for three times repeatedly. If
the moment is smaller than 18Nm, it
indicates adjusting arm has been
damage and needs to be replaced
the adjusting arm assembly.

Brake

Front brake has the same structure
with the rear brake. It is shoe brake
with camshaft with fixed sustainer.
When braking, front and rear shoe
slices of the brake press to the rotat鄄
ing brake drum by the action of the
same push force; so the rear brake
shoe is called power-reducing brake
shoe. All above lead to imbalance of
forces that front and rear brake
shoes press on the brake drum, so
this kind of brake is called simple
imbalanced brake.
Clearance between friction disc of the
brake shoe and the brake drum must
be proper, before adjusting the clear鄄
ance, make the front wheel off ground;
adjusting steps are as follows:

Full adjustment

1. Loosening fixed nut of brake shoe
bearing pin and nut of binding bolt
on cam bracket.
2. Rotate brake shoe bearing pin so
as to make clearance between front
shoe and bearing pin end the same
as that between rear shoe and bear鄄
ing pin.
3. Start braking, make brake shoe
friction disc lean against brake drum
closely and brake camshaft auto鄄
matic positioned and tighten nut of
binding bolt on support frame.
4. Release braking and rotate worm
so as to make brake shoe friction
disc lean against brake drum closely.
Then counter -rotate worm, released
by 3/4r, brake drum should be rotate

48

freely.
5. Test drive after adjustment, check
working condition of brake, whether
the brake drum get hot and whether
braking distance is proper. If not,
readjust it

Parts checking

To move the worm of brake arm to
adjusting the distance between
brake assembly and brake drum .
The way院 to the worm for clockwise
and move it again and again when it
can moved.Then move the worm for
couter -clockwise to 1 辕 2要3 辕 4circle.
At last the drake drum work agility .
The distance between brake friction
piece and brake drum is 0.25c要
0.4mm袁camshaft is 0.45mm.

Brake valve

Brake valve is to adjust and control
the whole brake system.
Use and maintenance
1)Take care of it
a) Should check the tube pressure
before driving, be air pressure mea鄄
sure is 0.6 MPa square can drive,
while driving in normally is in the O.
74 - 0.84 MPas,should park the car
whether leak air or not and whether
the compressor normal work or not.
b)When driving the truck to check
brake system. If it has something
wrong should be change it for an鄄
other one.
c)The damage of the brake shoe
plate is too big, then changing an鄄
other one. The piece should be the

same new ones and do not have
dirty oil, shatter, chap.
d)To change the friction and install
shoe plate and brake cam again in
order to adjusting the friction piece
and the brake cam.
2)Shedule time maintenance:
a) The first maintenance (1500-2000
kms)
i. To excluding the oil from the gas
cylinder.
ii. To fill with grease where need it.
iii. To checking and adjusting the
tighten about air compressor .
b) The second maintenance(10000要
12000km)
i. Disassemble and adjust the brake
and adjust the distance between
brake shoe friction piece.

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series trucks

ii Check the air compressor and
clean the dust of air valve.
iii. Check the brake involucra which
needs news to changing it.
c) The third maintenance (24000要
30000km)
i. Check and adjust the brake valve .
When it need new one then change it
ii. Check the brake valve pipe .
When it need new one then change it
iii. Clean all the pipe in order to keep
it liquidity.

1.2 Hydraulic brake system

1) General Structure
The running brake system is hy鄄
draulic. It is composed of vacuum

booster, vacuum cylinder, master
cylinder, control mechanism, brake
tube, front brake and rear brake. It is
sensitive and reliable, and it is sim鄄
ple to manipulate. See the last figure.
If you feel braking power is not suffi鄄
cient when brake pedal is depressed
completely and oil level is normal,
there may be air in brake system.
Bleed system in follow sequence.
Firstly, bleed RR brake; secondly,
bleed LR brake; thirdly, bleed RF
brake; then bleed LF brake. Follow
these steps:
a. Clean air -drain screw of main
cylinder and wheel cylinder;
b. Remove oil -drain plug of main
cylinder or reservoir and fill it with
brake fluid until fluid level reach the

1尧Control mechanism

2尧Vacuum booster

3尧Master Cylinder

4尧Reservoir

5尧Vacuum cylinder

6尧Brake tube

7尧Front & Rear brake

the picture of running brake

connect to engine

vacuum pump

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