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1. Parking brake system
1) Brief description of structure
Parking brake system is composed
of parking brake, control cable as鄄
sembly and control handle (the right
picture). Parking brake is a brake of
center-drum type that is installed on
rear side of the transmission, acts on
the drive shaft and is mainly used in
parking as well as in emergency
working with foot brake. Control han鄄
dle and parking brake pull arm are
connected by flexible shaft; diameter
of the steel wire inside the flexible
shaft is 椎3.5mm. Parking brake is
composed of backboard, parking
brake shoe with friction disc, adjust鄄
ing bolt assembly and return spring.
2) Adjusting
Clearance between parking brake
drum and friction disc as they do not
contact is 0.65mm, and the upper
clearance is as same as the lower
clearance. Because of friction disc
wearing, this clearance must be ad鄄
justed in time. The steps of adjusting
are shown as follows:
a. Jack up the rear axle to make one
wheel off ground.
b. Put the parking brake handle to
the lowest position, the gear shifts to
neutral position.
c. Turn the small hole on the brake
drum to the lowest side, put a screw鄄
driver into the hole and toggle the
gear-type adjusting bolt till the brake
drum can be stopped completely,
and then return the adjusting bolt by
2-6 teeth.
If above adjusting is executed cor鄄
rectly, when the parking brake is
tensed, the vehicle can stop on a
20% ramp; the vehicle cannot start at
2nd gear.
3) Using and inspection
Check and adjust clearance between
the brake and the brake shoe slice
regularly.
2. Service brake system
2.1 Air brake
1) Brief description of this system
Comparing with hydraulic brake, air
brake can brings greater braking
force under the condition that force
on the pedal is not great and the
pedal stroke is not long; at the same
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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 brake does not work, the
vehicle still can brake safely.
2) Structure and theory (referring to
the following diagram)
1. 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 separates
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
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
HFC1045
series trucks