1 Brake pressure is insufficient

Fault symptoms:

The braking failure caused by insufficient air pressure is manifested as that the air pressure expression is less than the specified pressure value (0.45-0.70Mpa), and the braking does not respond when the brake pedal is pressed.

Cause of failure:

1) The pipeline leaks, the gas in the gas reservoir has no pressure or the pressure is too low, which is not enough to promote the afterpump group to produce braking force.

2) The air compressor is not working properly and cannot produce enough compressed air.

3) The check valve is rusted and stuck, resulting in no air intake to the reservoir or slow air intake.

4) The oil drain plug of the oil-water separator is not tightened, and the air leakage is serious.

5) The pressure regulator leakage is serious.

Troubleshooting:

First of all, check the leakage of the pipeline, and then check the working state of the air compressor. Remove the air compressor outlet pipe and press the outlet port with your thumb. If the exhaust pressure is low, it indicates that the air compressor is faulty. If the air compressor is in good working condition, then check the oil drain plug or pressure regulator of the oil-water separator to avoid by-passing, and finally check the two one-way valves in the tee joint. The one-way valve jam will cause that the air can not be injected into the air storage cylinder or the air intake is slow.

.2 Brake failure

Fault symptoms:

When the loader is running, it cannot slow down and stop during braking.

Cause of failure:

1) Insufficient brake pressure, can not push the brake piston action.

2) The brake valve fails, the piston is stuck or the compensation hole and vent are blocked, and sufficient air pressure cannot be generated.

3) There is air in the brake tubing, resulting in oil pressure fluctuations or insufficient flow, which cannot promote the brake piston action.

4) No brake fluid or insufficient brake fluid, resulting in insufficient brake fluid oil into the brake cylinder, brake cylinder output power is low, can not promote the brake piston action.

5) The brake tubing is broken or the tubing joint is leaking oil, so that the brake fluid oil amount and pressure into the brake cylinder are reduced.

6) The booster cylinder piston is stuck or the seal ring is damaged, and the output brake fluid oil and pressure are reduced.

7) Caliper disc brake cylinder oil leakage is serious, a large amount of pressure oil leakage, can not push the brake piston action.

8) The piston in the cylinder of the clamp disc brake is stuck, and the piston cannot move.

9) The brake friction sheet is sticky with oil or seriously worn, the friction coefficient is reduced or the brake gap is increased, and the braking force is decreased.

Fault diagnosis and removal:

1) Check the brake pressure, eliminate the fault of low brake pressure, and ensure that the brake pressure value is 0.45-0.70Mpa.

2) When you step down the brake pedal, the air pressure is normal and the brake pedal is not moving, indicating that the brake control valve piston is stuck. Disassemble the brake valve and repair or replace it.

3) Step on the brake pedal, the pedal position is very low, and then continue to step on the pedal, the pedal gradually rises, but the brake pedal feels very weak, the braking effect is not good, indicating that there is air in the brake system, which should be excluded.

4) Continuously step on the brake pedal, there is a heavy feeling, but the pedal position gradually drops, indicating that the brake system is leaking oil, should be checked and repaired, if necessary, remove the brake for maintenance, replace the rectangular seal ring or brake piston.

5) The brake pedal is still weak after the air in the oil pipe is removed, open the refueling port cover, and find that the brake fluid has a violent flipping phenomenon, indicating that the seal in the caliper disc brake is deformed or damaged, should be inspected and replaced.

6) The piston in the cylinder of the clamp disc brake is stuck, and the piston and seal should be repaired.

7) When the brake friction plate is worn to 1/3 of the original thickness, the friction plate should be replaced to prevent damage to the brake disc.

8) When the brake disc has deep grooves or serious deformation, the brake disc should be repaired or replaced.

2.3 Brake failure

Fault symptoms:

When the loader is running, the brake pedal will be pressed to the end, but it can not stop and quickly slow down and continue to slide.

Cause of failure:

1) There is air in the brake tubing or brake cylinder, resulting in oil pressure fluctuations or insufficient flow.

2) Brake pedal free travel is too large.

3) Brake valve seals, booster cylinder seals, brake cylinder seals wear seriously, or cylinder and piston wear seriously caused by air leakage, oil leakage.

4) The compensation hole or vent of the brake valve is blocked.

5) Brake tubing rupture or tubing joint oil leakage.

6) The gap between the brake disc and the friction disc is too large.

7) Friction sheet surface hardening, rivet outcrop or oil.

8) Brake fluid quality is not good, easy to heat evaporation.

9) The brake pipe is depressed or blocked.

Fault diagnosis and removal:

1) Check the brake pressure, eliminate the fault of low brake pressure, and ensure that the brake pressure value is 0.45-0.70M.

2) The position of the brake pedal is very low, and then the pedal can gradually rise when the treadboard is continuously stepped, but the reaction force is small and the braking effect is not good, indicating that there is air in the brake tubing or brake cylinder, which should be excluded.

3) One foot brake is not effective, the pedal position gradually rises when continuously stepping the brake pedal, and the reaction force is large, and the braking effect is good. Note If the free travel of the brake pedal is too large or the gap between the friction disc and the brake disc is too large, check the free travel of the brake pedal first, and then adjust the gap between the friction disc and the friction disc.

4) Continuously step on the brake pedal and feel heavy, but the position of the brake pedal gradually drops, indicating that the brake system is leaking oil, should be checked and repaired, if necessary, remove the brake for maintenance, replace the rectangular sealing ring or brake piston.

5) The brake pedal is still weak after the air in the oil pipe is removed, and the brake fluid is violently turned after opening the refueling port cover, indicating that the seals in the caliper disc brake are deformed or damaged, and the damaged parts should be replaced.

6) The pedal position is very low when you step down the brake pedal, and the pedal position cannot be raised when you step on the brake pedal continuously. Generally, the brake valve vent hole or compensation hole is blocked, and it should be drained.

7) When stepping down the brake pedal, the free travel and height of the pedal meet the requirements, and it is not weak to sink, but the braking effect is not good, which is the fault of the caliper disc brake, which may be caused by the hardening of the friction sheet, the appearance of the rivet, the serious oil pollution, and the deformation of the brake disc. At this time, the brake should be repaired and the brake disc polished if necessary.

2.4 Braking deviation

Fault symptoms:

During the driving of the loader, both sides of the wheels can not be braking at the same time, or one wheel stops the other side of the wheel to rotate, so that the vehicle is tilted to one side, resulting in the vehicle can not travel along the straight line.

Cause of failure:

1) The contact area and gap size between the left and right sides of the wheel and the brake disc are inconsistent.

2) Individual wheel friction pieces have oil, hardening or exposed rivets.

3) The friction plate material on the left and right sides of the wheel is inconsistent.

4) There is air in the individual brake cylinder, the piston movement is blocked, or the tubing is blocked.

5) The tire pressure on the left and right sides is different.

6) Individual brake disc deformation.

The root cause of braking deviation is the unequal braking force of both wheels.

Fault diagnosis and removal:

When the loader is driving, when the foot brake is used, the vehicle tilts to one side, it means that the wheel brake on the other side fails. After stopping, check the drag marks on the road on both sides of the wheel. If the drag mark is short or no drag mark, the wheel brake will not work. When it is determined that a wheel brake is not working, the deformation of the brake disc should be checked and the air in the brake cylinder should be excluded. If it still does not work, disassemble the wheel brake, check the brake cylinder piston and seals, find out where the fault is located, and make necessary repairs.

2.5 Brake drag

Fault symptoms:

The loader lifts the brake pedal after braking, and all or individual wheels still have braking effect, resulting in brake disc heating and weak driving, commonly known as "brake does not return".

Cause of failure:

1) The free travel of the brake pedal is too small or the brake pedal return is poor.

2) The control valve piston return spring is too soft or broken, the piston is stuck, etc.

3) The brake valve bowl seal is swollen, making the return spring weak.

4) Brake piston does not return, etc.

Fault diagnosis and removal:

1) After the loader runs a distance, touch the brake disc of each wheel by hand. If all the brake disc is hot, it indicates that the fault is in the brake valve; If an individual brake disc is hot, it indicates that the brake of the wheel is faulty.

2) For the phenomenon of all brake discs heating, the brake valve should be disassembled, and the working conditions of the seals, pistons, air holes, compensation holes, and return spring should be replaced if necessary.

3) For the phenomenon of individual brake disc heating, the check should first loosen the brake bleed screw, if the brake fluid is rapidly emitted, the piston is returned, it can be identified as the oil pipe blockage, should be dredge the brake pipe; If the brake piston still does not return, the brake should be removed for repair.

3 Maintenance of brake system

In order to ensure that the brake system of the regular ZLM50E loader is always in good working condition, the following inspection and maintenance matters should be paid attention to in use:

1) Regularly check the connection fastening of each part of the brake.

2) Check the brake valve, brake cylinder, booster cylinder and pipeline regularly for leakage. If there is oil leakage, it should be removed in time. If there is oil on the friction plate, it should be cleaned in time.

3) Clamp disc brake because the brake disc is exposed outside, the dirt on it should be cleaned after the completion of the work task every day.

4) Check the working condition of the brake pedal, step on the brake pedal when there is no sign of stagnation, relax can quickly return to the position.

5) Check whether there is air in the hydraulic system. If there is air, step on the pedal and feel soft and weak, and the braking effect is reduced.

6) If necessary, check the amount of brake fluid, and the brake fluid level should be 15-20mm from the edge of the refueling port.

7) The oil-water separator needs to be drained once every 50h, and it needs to be drained every day in winter.

8) After completing the daily work tasks, release the water from the air reservoir after the maintenance.

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