Symptom:

1. The clearance between throttle valve and hole is too large, with leakage and internal leakage

2. The orifice is blocked or the valve element is stuck

Fault analysis:

1. Check the internal parts for damage, repair and renew them, and pay attention to the oil seal at the joint

2. Disassemble and clean, replace with new oil, so that the movement speed of the valve element is flexible, and the movement speed is unstable, such as gradually slowing down, suddenly increasing and jumping.

3. There are medium impurities adhering to the edge of the orifice, reducing the oil passage section and slowing down the speed.

4. The performance of throttle valve is poor, and the adjustment position changes due to vibration during low-speed movement.

5. There is leakage inside and outside the throttle valve.

6. In the simple throttle valve, the speed changes abruptly due to the change of system load.

7. When the oil temperature rises, the viscosity of the oil decreases, making the speed gradually increase.

8. The damping device is blocked, there is air in the system, and the pressure changes and jumps.

Troubleshooting:

1. Disassemble and clean relevant parts, replace with new oil, and always keep the oil clean.

2. Throttle interlock device was added.

3. Check the fitting clearance of the parts, repair or replace the out of tolerance parts, and close the joints strictly.

4. Check whether the function of system pressure, pressure relief device and other components and the control of overflow valve are normal.

five Hydraulic system After stabilizing, adjust throttle valve or add oil temperature radiator.

6. Clean the parts, and set an exhaust valve in the system to keep the oil clean.