Service Manual of RS8160 Road Roller
SERVICE MANUAL
5 Brake System
Service Manual for G9165 Grader
CONTENTS 5
Brake System ....................................................................................................... 5-1
51 Service Brake System .......................................................................................... 5-1 511 System Composition and Working Principle .............................................. 5-1 512 Specification and Technical Description of Main Components ................. 5-3 513 Disassembly and Assembly Single-Circuit Foot Brake Valve ...................5-9 514 Disassembly and Assembly of Accumulator............................................. 5-11 515 Disassembly and Assembly of Prefill Valve ............................................. 5-13 516 Replacement of Brake Shoe ...................................................................... 5-15 52 Parking Brake System ....................................................................................... 5-19 521 Working Principle of Parking Brake ......................................................... 5-19 522 Disassembly and Assembly of Parking Brake Control Mechanism ......... 5-20 53 Diagnosis and Solutions for Common Faults of Brake System ........................ 5-22 523 Common Fault of Service Brake System .................................................. 5-22 524 Common Fault of Parking Brake System .................................................. 5-24
I
Service Manual for G9165 Grader
5
Brake System
The brake system of this grader consists of service brake system and parking brake system. The function of service brake system is to realize speed reduction and stop when the vehicle is running according to the operator ’s requirements. The parking brake is used for grader to brake under emergency conditions during operation or to keep loader stay at original position after stop, avoiding movement in the effect of inclined road or other external forces.
51 Service Brake System This machine adopts full hydraulic brake system. It has advantages of smooth braking, safe and reliable, simple structure, and convenient maintenance. The system
is
designed
with
drum-type
brake.
(Double-circuit service brake system is optional, when a circuit fails, the other brake circuit can still carry out braking, which improves the vehicle's safety).
511 System
Composition
and
Working Principle The service brake system is supplied by gear pump. During driving, the oil from the pump flows into the accumulator through prefill valve. When the operator steps on the brake pedal, high pressure oil stored in accumulator (or from the prefill valve) splits into two parts, flows into the wheel side brake cylinders respectively to engage braking. Meanwhile, the brake lamp switch will be trigged by pressure oil to turn on the brake lamp. Release the brake pedal, the pressure oil circuit to the brake valve will be cut off, and the hydraulic oil in the 5-1
Service Manual for G9165 Grader
wheel side brake cylinders will return to oil tank through valve, then the brake will be released and the brake lamp will be off. The prefill valve always takes supplying oil to the accumulator as first priority. The two accumulators will be charged to set pressure as long as the engine is running, to guarantee reliable braking. The brake valve controls the four rear wheel side brakes through hydraulic circuits, and braking pressure is determined by the pressure acted on brake valve.
Fig. 5-1 Composition of service brake system 1 Brake pump
2 Filter
3 Hydraulic oil tank
4 Joint
6 Oil return block
7 Brake valve
8 Accumulator
9 Pressure switch
10 Brake joint block
11 Right wheel side brake
5-2
5 Prefill valve
12 Left wheel side brake
Service Manual for G9165 Grader
512 Specification
and
Technical
Description of Main Components Prefill valve The prefill can keep the two accumulators at right pressure.
When the pressure of oil
in
the
accumulators drops to 12.4MPa or below, the prefill valve will charge them immediately. When the pressure of oil in the accumulators is charged to 16MPa, the prefill will stop charging.
1 2 3 4 Fig. 5-2 Prefill valve 1 Port O 2 Port T 3 Port A 4 Port P
Prefill valve for double-circuit brake system.
1 2 3 4 5 6 Fig. 5-3 Prefill valve 1 Low-pressure alarm switch 2 Port A1 3 Port P 4 Port A2 5 Port O 6 Port T
5-3
Service Manual for G9165 Grader
Brake valve The hydraulic brake valve is composed of valve body, oil channels and moveable valve block. Step the brake pedal, the corresponding oil channels will open to connect the inlet port and outlet port. Release the brake pedal, the inlet port and outlet port will be disconnected and the braking will be relieved.
1 2 3 4 Fig. 5-4 Foot brake valve 1 Port A1 2 Port A2 3 Port T 4 Port P
Foot brake valve for double-circuit brake system.
1 23 4 56 Fig. 5-5 Foot brake valve 1 Port T1 2 Port T2 3 Port A1 4 Port A2 5 Port P1 6 Port P2
5-4
Service Manual for G9165 Grader
Bladder type accumulator Accumulator is used to store pressure oil for braking. Its principle is to store the pressure liquid and capsule with pressure in a sealed housing and it is used to brake by absorbing and releasing the liquid due to the changing pressure. When brake pump is working,
it
injects
the
pressure
fluid
into
accumulator through prefill valve to store energy. Then, the gas is compressed in the capsule, so that 1 Fig. 5-6 1 Accumulator
the pressure of liquid is the same with that of capsule, to obtain energy reserves. The air in capsules is nitrogen. The accumulator can store sufficient pressure oil. In case of system failure (the prefill valve is not able to charge), the pressure oil stored in the accumulator can conduct 6 times braking.
When the pressure of oil in accumulator is lower than 11.5MPa, low-pressure alarm switch will be trigged and the alarm indicator on instrument panel will be on. You should stop the vehicle for inspection immediately.
1 Fig. 5-7 1 Lo-pressure alarm switch
5-5
Service Manual for G9165 Grader Method to inflate the accumulator
1.
Firstly park the machine on flat ground, continuously operate the service brake and parking brake several times, and drain the high pressure oil in accumulators as far as possible. Then slowly loosen the oil pipe on the bottom of accumulator and drain the residual pressure out of the accumulator.
2.
Remove the protective cap of inflation valve from top of the accumulator.
3.
Connect the end with pressure gauge of inflation tool to the inflation valve on top of accumulator, and the other end should be connected with nitrogen cylinder.
4.
Open the switch of nitrogen cylinder. After the inflation pressure of inflation tools is stable, slowly open the switch on the inflation tools, i.e., open the inflation valve in the accumulator and fill air into the accumulator.
5.
Pressure may be instantly achieved, then switch off the nitrogen cylinders, and see whether the pressure value still indicates the specified value after the gauge of inflation tools come to stable. If not, then refill it. If the pressure is high, drain the air through the inflation plug through
Fig. 5-8 Working principle of accumulator
inflation tools, and reduce the pressure to the appropriate value. 6.
After air is filled to required pressure, firstly switch off nitrogen cylinders, and then close the switch on inflation tools.
7.
Remove the air inflation tool.
8.
If accumulator leaks (Wipe accumulator head with oil, and if there is leakage, bubbles will come out. Hit the inflation valve inside the
5-6
Service Manual for G9165 Grader
accumulator with a hammer and a screwdriver. Pull it down, and then quickly reset it until the sealing surface can be connected. 9.
Install protection cap of accumulator inflation valve.
Brake assembly The brake assembly comprises brake and brake drum. When the operator steps on the brake pedal, high pressure oil stored in accumulator (or from the prefill valve) splits into two parts, flows into the wheel side brake cylinders respectively. Brake 1 Fig. 5-9 1 Brake
2
2 Brake drum
cylinder pushes the brake shoe to expand outside, to produce friction resistance between the brake and brake drum inner wall, so as to realize braking.
The brake mainly consists of brake carrier, brake cylinder, brake shoe assembly and accessories. The brake assembly is equipped with brake parts clearance automatically adjustable cylinder. When the friction plate is worn off, the clearance between the friction plate and brake drum can be adjusted automatically to offset the wear loss. 1 2 3 4 Fig. 5-10 Brake assembly 1 Brake cylinder 2 Brake shoe assembly 3 Brake carrier 4 Return spring
5-7
Service Manual for G9165 Grader
Deflation of brake system After overhauling of brake system, there will be air in
the
pipeline,
which
will
affect
brake
performance. So air bleeding must be done after the overhaul. The air bleeding should be performed by two men cooperatively. Each wheel side brake is designed with deflating valve (air bleeding valve), do the air bleeding according to the following instructions: 1 Fig. 5-11 1 Plastic cap
1.
Remove the plastic cap of air bleeding bolt.
2.
Connect a hose to the air bleeding bolt, and put the other end of the hose into a container.
3.
Loosen the air bleeding bolt about half a turn, and tread down the brake pedal. Once there is oil overflowing, tighten the bolts immediately, and release the brake pedal.
ATTENTION The overflowing oil could be transient, so you need to perform the air bleeding operation coordinately and cooperatively.
1 Fig. 5-12 1 Container
2
4. 2 Rubber hose
The air in other brakes should be drained out according to related requirements as well.
5-8
Service Manual for G9165 Grader
513 Disassembly
and
Assembly
Single-Circuit Foot Brake Valve Disassembly of single-circuit foot brake valve
1.
Tread down the brake pedal repeatedly to unload the brake system.
2.
Disconnect the oil pipes from port A, port T and port T of foot brake valve.
ATTENTION When dismantling the hydraulic pipes, do not screw off the nut connecting to the oil
1 2 Fig. 5-13 1 Port T 3 Straight joint
3
4
port rashly. Loosen the nut gradually until the oil spills out so as to prevent the oil
2 Port P 4 Port A
splashing due to incomplete pressure relief. When dismantling the hydraulic pipeline, necessary protective measures shall be taken for each pipeline and oil port to prevent debris like dust from entering the brake system.
3.
Remove the four straight joints.
4.
Remove the three connecting bolts of foot brake valve and cab.
5.
1 Fig. 5-14 1 Bolt
5-9
Take the brake valve out of cab.
Service Manual for G9165 Grader Assembly of single-circuit foot brake valve
1.
Fix the foot brake valve on cab with three bolts.
1 Fig. 5-15 1 Bolt 2.
Install the four straight joints to the valve. 58±3Nm
3.
Connect the oil pipes to port A, port T and port T of foot brake valve accordingly. 45±4.5Nm
1 2 Fig. 5-16 1 Port T 3 Straight joint
3
4 2 Port P 4 Port A
5-10
Service Manual for G9165 Grader
514 Disassembly
and
Assembly
of
Accumulator Disassembly of accumulator
1.
Remove
the
six
connecting
bolts
of
accumulator periphery board and frame.
1 Fig. 5-17 1 Periphery board
2 2 Bolt
2.
Tread down the brake pedal repeatedly to unload the brake system. Remove the oil pipe from the bottom of accumulator.
ATTENTION When dismantling the hydraulic pipes, do not screw off the nut connecting to the oil port rashly. Loosen the nut gradually until the oil spills out so as to prevent the oil
1 2 Fig. 5-18 1 Accumulator
splashing due to incomplete pressure relief.
2 Oil pipe
When dismantling the hydraulic pipeline, necessary protective measures shall be taken for each pipeline and oil port to prevent debris like dust from entering the brake system.
5-11
Service Manual for G9165 Grader
3.
Loosen the U-shape fixing bolt of accumulator and take down the bolts, nuts and gaskets, and then take out the accumulator and remove the straight joint.
ATTENTION The accumulator may still contain pressure even removed from the machine, and that is
1 Fig. 5-19 1 U-shape bolt 3 Accumulator
2
so-called preload pressure. You must be
3
very careful when handling or operating on the accumulator.
2 Rubber mat
Assembly of accumulator
1.
Fix the accumulator on the support with U-shape bolt, rubber mat, nuts and gaskets.
1 Fig. 5-20 1 U-shape bolt 3 Accumulator
2
3
2 Rubber mat
2.
Install the straight joint and connect the oil pipe. Pipe joint: 310±31Nm Oil pipe: 70±7Nm
1 2 Fig. 5-21 1 Accumulator
2 Oil pipe 5-12
Service Manual for G9165 Grader
3.
Install the accumulator periphery board to rear frame with bolts.
1 Fig. 5-22 1 Periphery board
2 2 Bolt
515 Disassembly
and
Assembly
of
Prefill Valve Disassembly of prefill valve
1.
Remove
the
six
connecting
bolts
of
accumulator periphery board and frame.
1 Fig. 5-23 1 Periphery board
2 2 Bolt 2.
Disconnect the oil pipe (to oil tank) from port O of prefill valve.
3.
Disconnect the oil pipe (to high-pressure filter oil outlet) from port P of prefill valve.
4.
Remove the T-junction from port A of prefill valve.
5.
Remove the T-junction from port T of prefill valve.
1 4 Fig. 5-24 1 Oil pipe (Port O) 3 T-junction (Port T) 4 T-junction (Port A)
2
3 2 Port P
5-13
Service Manual for G9165 Grader
6.
Remove the fixing bolts of prefill valve periphery. Take down the valve.
1 Fig. 5-25 1 Bolt
Assembly of prefill valve
1.
Install the fixing bolts of prefill valve periphery.
1 Fig. 5-26 1 Bolt
2.
Install the T-junction to port A of prefill valve. Install the T-junction to port T of prefill valve. 70±7Nm
3.
Connect the oil pipe (to high-pressure filter oil outlet) to port P of prefill valve. 70±7Nm
4.
Connect the oil pipe (to oil tank) to port O of prefill valve.
1 4 Fig. 5-27 1 Oil pipe (Port O) 3 T-junction (Port T) 4 T-junction (Port A)
2
110±10Nm
3 2 Port P
5-14
Service Manual for G9165 Grader
5.
Install the six connecting bolts of accumulator periphery board and frame.
1
2
Fig. 5-28 1 Periphery board
2 Bolt
516 Replacement of Brake Shoe 1.
Remove the rear wheels. Refer to 7 Frame, Wheels & Working Device for details.
1 Fig. 5-29 1 Tire
2.
1 Fig. 5-30 1 Brake drum
5-15
Remove the brake drum.
Service Manual for G9165 Grader
3.
Remove the end cover.
4.
Remove the splined hub.
5.
Remove the return spring.
1 Fig. 5-31 1 End cover
1 Fig. 5-32 1 Splined hub
ATTENTION Be careful when disassembling the spring, and protective measures shall be taken.
1 Fig. 5-33 1 Return spring
5-16
Service Manual for G9165 Grader
6.
Replace the brake shoes.
7.
Install the return spring.
1 Fig. 5-34 1 Brake shoe
ATTENTION The new brake shoe must be grinded and repaired to ensure necessary contact area between the brake shoe and brake drum. Besides, to avoid unbalanced braking force, the two brake shoes should be replaced together.
1 Fig. 5-35 1 Return spring
8.
1 Fig. 5-36 1 Splined hub
5-17
Install the splined hub.
Service Manual for G9165 Grader
9.
Install the end cover.
1 Fig. 5-37 1 End cover
10. Install the brake drum.
1 Fig. 5-38 1 Brake drum
11. Install the rear wheels. 700~800Nm 12. Recover the machine.
1 Fig. 5-39 1 Tire
5-18
Service Manual for G9165 Grader
52 Parking Brake System 521 Working Principle of Parking Brake The parking brake system is used to keep loader stay at original position after stop, to avoid unexpected movement due to inclined road or external forces. The system consists of brake handle, parking brake and fixed plate. Hand brake operating mechanism comprises hand brake, control handle, and control wire (flexible shaft). When pulling up the brake control handle, the pull rod will swing and the cylindrical can at 1 2 3 Fig. 5-40 Schematic diagram of parking brake system 1 Parking brake is relieved 2 Parking brake is engaged 3 Parking brake assembly
the end of the pull rod will rotate to expand the two brake shoes (friction plates), the brake shoes will press against the inner wall of rotating brake drum to realize braking, and the hand brake indicator light will be on. Generally, the failure rate of parking (hand) brake system is very small. But if basic maintenance tasks are not being carefully addressed, phenomena like brake slide, wear of friction plates, crack of brake drum and brake dray (the grader is not able to move after reliving the brake) may occur. The brake slide is caused by severe worn friction plates. The main causes of premature wear of friction plate are: there is oil on friction plate, or swell of
1 Fig. 5-41 1 Hand brake indicator light
friction plates (exposed to moisture). The brake drag is mainly caused by swell of friction plate. Thereby, you should clean the friction plates periodically to keep them clean and dry.
5-19
Service Manual for G9165 Grader
522 Disassembly Parking
and
Assembly
Brake
of
Control
Mechanism Disassembly
of
parking
brake
control
mechanism
1.
Remove the fixing screws of parking brake control handle shield.
1
2
Fig. 5-42 1 Screw 2 Parking brake control handle
2.
Screw off the adjusting nut of flexible control shaft.
3.
Use a plier to remove the cotter pin and connecting pin.
4.
1
2
Fig. 5-43 1 Adjusting nut 2 Connecting pin, cotter pin
5-20
Take down parking brake assembly.
Service Manual for G9165 Grader Assembly of parking brake control mechanism
1.
Fix the parking brake control handle shield on cab floor with screws. Then set the brake handle in the lowest position (non-braking state). Connect the flexible control shaft and the hand brake.
1
2
Fig. 5-44 1 Screw 2 Parking brake control handle
2.
Connecting the parking brake control shaft to the parking brake with pin and cotter pin, and fix the shaft on the support.
1
2
Fig. 5-45 1 Adjusting nut 2 Connecting pin, cotter pin
5-21
Service Manual for G9165 Grader
53
Diagnosis and Solutions for Common Faults of Brake System
Common faults of full hydraulic brake system are: Insufficient foot brake force, parking b rake can’t be released normally, insufficient parking brake force, accumulator charging failure or too long charging time, no inching braking, low service brake pressure alarm indicator light is on, and the brake lamp doesn’t work.
523 Common Fault of Service Brake System Table 5-1 S/N
Problems
Diagnosis
Solutions 1.
2. 1. 2. 3.
1
Insufficient foot brake force
4. 5. 6. 7. 8.
There is air in brake line. Brake valve is faulty. There is leakage in the brake line. Prefill valve does not work. Accumulator is damaged. Friction plate of wheel side brake is worn to the limit. The pilot pump is too old to work. There is oil (dirt) on brake shoe
3.
4. 5. 6. 7. 8.
2
Charging frequency of prefill valve is too fast
1. 2. 1.
3
Accumulator charging failure
2. 3. 4.
Pressure of accumulator capsules is too low. Prefill valve does not work. There is no oil or oil level is too low in hydraulic tank. Pump is too old to work There is air in accumulator. Prefill valve does not work
5-22
1.
Drain the air. There are deflating valves on left and right wheel side brakes. Check brake valve, detect whether the maximum braking pressure of brake valve outlet is equal to the brake pressure required by the system. If the pressure is not normal, adjust the brake pressure or replace the brake valve. Check whether the brake pipelines and connectors leak. If the connector is loose, retighten it; if the seal is damaged, replace it. Replace prefill valve. Check the accumulator Replace friction plate. Check the pressure or flow of pump. Clean the brake shoe.
2.
Check the air pressure in the accumulator capsules. Replace prefill valve.
1. 2. 3. 4.
Check the oil level in the tank. Check the pump pressure or flow. Drain the air. Replace the prefill valve.
Service Manual for G9165 Grader
1.
4
Accumulator charging time is too long
2. 3.
1. 5
The brake lamp doesn’t work
6
Low service brake pressure alarm indicator light is on
2.
Pump is too old to work and cannot deliver all flow or pressure. Prefill valve does not work. Accumulator capsule is damaged and nitrogen is leaked. The brake lamp damaged. There are system faults the working process grader and oil pressure decreasing.
1.
Check the pressure or flow of pump. 2. Replace the prefill valve. 3. Remove, check or replace capsules.
is in of is
1.
System pressure is inadequate, in the short time of starting grader. 2. System failure, the oil pressure is decreased.
1. 2.
Check the brake lamp. Stop the machine to check it.
1.
Please wait that the alarm will stop automatically if system oil pressure is sufficient. 2. Stop the machine for inspection
1.
7
Low service brake pressure alarm indicator light is on when service brake is engaged
1. 2.
There is leakage in brake line. Pressure of nitrogen in the accumulator capsule is abnormal (caused by sealing failure).
Check whether the brake pipes and pipe joints have leakage problem. If the pipe joint is loose, retighten it; if the seal is damaged, replace the seal. 2. Unload the brake system thoroughly before measuring the nitrogen pressure. Methods: Shut down the engine and tread down the brake pedal repeatedly to unload the brake system, and use pressure gauge to measure the nitrogen pressure.
8
No inching braking
Brake valve failure.
Detect whether the maximum pressure of brake valve outlet is normal. If the maximum pressure of export is much greater than required system pressure, replace the brake valve.
9
Off tracking when braking
Inflation pressure of the tires are not uniform.
Try to keep the tire pressure uniform as far as possible.
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Service Manual for G9165 Grader
524 Common Fault of Parking Brake System Table 5-2 S/N
Problems
Diagnosis
Solutions
1.
1
Parking brake failure
2
Parking brake control handle cannot fixed
The clearance between brake drum and brake shoe is too large, the contact area is small. 2. There is oil on the brake shoe. 3. The expansion force of the brake shoe is not enough.
The parking brake handle is faulty.
control
be
5-24
1. 2. 3.
Readjust it as required. Clean brake shoe. Adjust the stroke of parking brake control mechanism.
Check whether the parking brake control handle deformed or jammed, whether the spring is broken. If not, check whether it is caused by screw loose.