A Brief Analysis of Hydraulic Fault Handling in Garbage Trucks

The hydraulic system of a garbage truck includes an oil pump, front valve, front valve control lever, rear valve, rear valve control lever, garbage bin cylinder, slide plate cylinder, scraper cylinder and multi-stage push plate cylinder, as well as flexible and hard oil pipes, joint bodies and oil tank assemblies, etc. Common faults of garbage trucks are as follows

First, the compression mechanism cannot generate sufficient payload

1. Check whether the liquid level in the fuel tank meets the requirements and whether the system is leaking oil. Fill up the fuel tank, tighten the oil line pipe joints, and replace the damaged oil pipes.

2. Check whether the ball valve switch is open.

3. Check whether the oil suction pipe is blocked or damaged, and clean or replace the oil pipe.

4. Check the system pressure. The working pressure of the hydraulic system of this vehicle is 1.5 Mpa.

The system pressure is too low. Adjust the pressure valve on the front valve. If the pointer of the pressure gauge does not move when the adjustment screw is screwed in, it indicates that the problem may lie in the pressure valve, the pump or the oil cylinder of the garbage bin. Operate the handle of the garbage bin cylinder control lever to make the garbage bin cylinder move, and listen to the noise of the cylinder at the same time. If there is noise, the seal of the oil cylinder should be replaced. If the oil cylinder is normal, check whether the pressure valve has been opened by dirt. If the pressure valve is normal, the oil pump needs to be repaired.

• Check the pressure of the scraper cylinder. The working pressure of the scraper cylinder of this vehicle is 13.1 Mpa. If the pressure is too low, operate the scraper cylinder and listen for the noise from the cylinder. If there is noise, replace the cylinder seal. If the pressure is normal, adjust the hydraulic lock reset pawl of the scraper cylinder control valve.

★ Adjustment of the hydraulic locking reset pawl of the scraper: Use a hex wrench to screw in the pawl on the scraper control valve of the rear valve until the scraper control lever handle does not suddenly jump back to the middle position at the end of the cylinder stroke. Then screw out the pawl until the control lever handle can suddenly jump back to the middle position. Make adjustments using special tools.

• Check the pressure of the skateboard cylinder. The working pressure of the oil cylinder of this vehicle's skateboard is 13.8 Mpa. If the pressure is too low, operate the slide plate cylinder and listen for the noise from the cylinder. If there is noise, replace the cylinder seal. If the pressure is normal, adjust the hydraulic lock reset pawl on the slide plate cylinder control valve.

★ Adjustment of the hydraulic lock reset pawl of the skateboard: Use a hex wrench to screw in the pawl on the skateboard control valve of the rear valve until the skateboard control lever handle does not suddenly jump back to the middle position at the end of the cylinder stroke. Then screw out the pawl until the control lever handle can suddenly jump back to the middle position. Make adjustments using special tools.

Check the set pressure of the back pressure valve of the push plate control valve. The working pressure of the push plate cylinder of this vehicle is 13.8 Mpa, and the set pressure of the back pressure valve is 3-10.4 Mpa. Set the back pressure of the push plate according to the garbage compaction status to achieve the maximum effective compaction load.

Second, the system operates slowly, unstably, or even fails to work

1. If there is no hydraulic oil in the system or the oil level in the tank is low, add oil to the tank and check for system leakage.

2. The viscosity of the hydraulic oil does not meet the usage requirements. Replace it with the oil recommended in this user manual.

3. If the fine oil filter or coarse oil filter is dirty or clogged, replace it with a new one and identify the cause of contamination.

4. Poor oil flow, restricted or blocked in the system may be caused by too dirty inside the hydraulic pipeline or damage to the inner wall. Clean the pipeline or replace the oil pipe.

5. The suction pipe of the oil pump is leaking. Repair or replace it.

6. If the oil pump is severely worn, it should be repaired or replaced, and the cause should be identified, such as incorrect installation or dirty oil.

7. Severe wear of components. Check and test for leaks both inside and outside pumps, valves, cylinders, etc. If there is abnormal wear and tear, find out the cause.

8. Hydraulic oil leakage in the pressure pipeline. Tighten the pipe joints and replace the damaged pipes or joints. Check whether the mating surfaces of the accessories are uneven.

9. Incorrect adjustment of components. Refer to the corresponding technical manual to learn about the correct adjustment of components.

10. The pressure valve is faulty or too dirty. Check whether the pressure valve can open at the rated pressure, whether there are any damaged seals, and clean the pressure valve. Check if the spring has any cracks.

11. The rotation direction of the oil pump is incorrect. Replace it with an oil pump that rotates in the correct direction.

12. The system is overloaded. Find out the vehicle load standard regulations and use the system at the prescribed limit load.

13. The oil pipe connection is improper. Correct the installation status and fix the hose properly.

14. The oil pump is not working. Check the power take-off box.

15. There is air in the system. Check whether there is any leakage in the suction pipeline of the system and whether the liquid level in the oil tank is correct.

16. The temperature of the hydraulic oil is low. When the system starts working, the viscosity of the hydraulic oil is too high. Before the system starts working, the oil temperature of the system should be brought to the working temperature.

17. The engine speed is insufficient.

Three. The oil temperature in the system is too high

If the control valve is operated for too long, the pressure valve will open. When not in use, the control lever should be returned to the middle position.

2. The selected oil does not meet the requirements. The oil recommended in this manual should be used to ensure the correct viscosity of the oil.

3. The engine speed is too high. Readjust the accelerator.

4. The pressure setting of the pressure valve is incorrect or the pressure valve is dirty. Clean the pressure valve and adjust its pressure.

5. Internal leakage. Check and test the internal and external leakage of the oil pump, valve and cylinder, etc. If there is abnormal wear, find out the cause.

6. If the movement of the valve core of the control valve is obstructed or it is in the fully open position, it is necessary to ensure that the valve core slides freely so that it can return to the neutral position.

7. The system has poor heat dissipation. Remove the accumulated sludge and dirt from the fuel tank, pipelines and other components.

Four. There is foam in the hydraulic oil of the system

1. The liquid level in the fuel tank is low. Add fuel to the required height. Check for system leaks.

2. There is water in the oil. Change to new oil.

3. The selected oil grade is incorrect. The oil recommended in this manual should be used instead.

4. The pipeline between the oil tank and the pump is leaking. Tighten the pipe joint or replace the suction pipe.

5. If the hydraulic hose is twisted or flattened, restricting the flow of oil, replace the oil pipe.

6. The sealing parts on the oil pump shaft are worn. Clean the sealing surface and replace the sealing parts. Check whether the oil pump is installed correctly and the cleanliness of the hydraulic oil.

Five. The oil pump makes a lot of noise during operation

The liquid level in the fuel tank is too low. Fill the fuel tank to the required height and check for system leaks.

2. The viscosity of the oil is too high. Switch to oil with a lower viscosity.

3. The oil pump's rotational speed is too high. Run the oil pump at the recommended speed and adjust the accelerator.

4. The oil suction pipe is blocked or squeezed, causing poor oil flow. Clean or replace the oil suction pipe.

5. If the internal organs of the oil pump are clogged due to accumulated oil sludge, disassemble the oil pump and pipelines, clean the hydraulic system, and identify the cause of contamination.

6. The fuel tank breather is clogged. Remove the respirator cover, rinse it and clean the respirator.

7. There is air in the hydraulic oil. Tighten or replace the oil suction pipe, check for system leaks, and replace the seals on the pump shaft.

8. The oil pump bearing or shaft is worn or scratched. If the parts are severely worn or scratched, replace the parts or the oil pump and find out the cause of the scratches.

9. Clogging of the coarse oil filter. Clean the filter screen.

10. The oil pump parts are broken or damaged. Repair the oil pump and find out whether the damage is caused by dirt or excessive pressure.

11. If there is a phenomenon of parts getting stuck together, repair the stuck parts, clean the parts and replace them if necessary.

Six. Oil pump leakage

The oil seal on the drive shaft is damaged. When replacing the oil seal, most faults are caused by dirty oil. Check the abrasive particles in the oil, clean the entire hydraulic system, and identify the cause of contamination. Check whether the drive shaft of the oil pump is centered. Improper installation can also cause wear of the seals. If the pump shaft is not aligned, it is necessary to check whether other parts are damaged.

2. The oil pump parts are loose or damaged. Check the tightness of all fasteners and joints. Check if there are any cracks in the oil pump body and identify the cause, such as excessive pressure or improper installation of the hose.

When the control valve is in the neutral position, the load decreases.

The oil circuit between the control valve and the cylinder is leaking or damaged. Tighten the oil pipe joint or replace the oil pipe, and check the sealing condition of the mating surface of the coupling parts and whether the contact surface is uneven.

2. Cylinder leakage: Replace the sealing parts and worn parts. If wear is caused by dirty oil, clean the hydraulic system.

3. Oil leakage from the control valve or pressure valve. Clean or replace the valve. Wear may be caused by dirty oil. Clean the hydraulic system and identify the cause of contamination.

4. When the joystick handle is released, the control valve does not return to the neutral position. Check whether the valve control lever is bent or deformed and whether there is any jamming at the connection parts. Check whether the adjustment of the control valve is correct and whether there are any broken parts.

Eight. The operating force of the control valve is too large

1. The joystick connection is misaligned or stuck. Reinstall.

2. The connecting bolts of the control valve body are loose. Tighten the bolts with the torque recommended by the manufacturer.

3. Fractures or scratches occur on the internal components of the valve. Repair or replace parts and find out the cause.

Ix. Oil leakage from the control valve

1. The connecting bolts of the valve body are too loose. Tighten the bolts to the torque required by the manufacturer, replace the O-rings between the valve bodies. If the O-rings are damaged due to dirt, clean the hydraulic system and identify the cause of the contamination.

2. The control valve part is broken. Repair or replace the valve and check the cause of the damage.

X. Oil leakage from the cylinder

The cylinder barrel is damaged. Replace the cylinder barrel and identify the cause of the damage.

2. Oil leakage from the piston rod seal. Replace the sealing parts and identify the cause of the wear. Both internal and external dirt may cause damage to the seals. Check if there are any scratches or misalignment on the piston rod and repair them in time.

3. The parts of the oil cylinder are loose. Tighten the parts until there is no oil leakage.

4. The piston rod is damaged. Check for any scratches or dents and replace the damaged piston rod.

When the control valve is in the low lift position, the cylinder descends.

Check whether the check valve of the lifting circuit is damaged. Repair or replace the check valve.

2. Oil leakage from the cylinder seal. Replace the seals, check if there are any contaminants in the oil that cause wear, and inspect whether the oil cylinder is improperly installed. There is a leakage in the pipeline or joint to the cylinder. Tighten the joint and check whether the mating surface of the coupling is uneven.