Common Faults and Elimination Methods of Directional Valves

1. Abnormal spool movement

(1) Fault phenomenon: abnormal movement of the spool (electromagnet failure).

Cause analysis: ①The circuit of the directional valve is faulty; ②The electromagnet cannot move or the coil is faulty; ③The control signal is not applied to the directional valve; ④The thrust of the electromagnet is too small.

Elimination method: ① overhaul the circuit; ② overhaul or replace the electromagnet coil; ③ load the control signal; ④ overhaul or replace.

(2) Fault phenomenon: abnormal movement of the spool (pilot solenoid valve fault).

Cause analysis: ①The spring is bent sideways; ②The valve core and the valve body are stuck.

Elimination method: ① Overhaul and replace the spring; ② Overhaul or replace the valve core and valve body.

(3) Fault phenomenon: abnormal movement of the spool (the spool is stuck).

Reason analysis: ①The gap between the valve core and the valve body is small; ②The machining accuracy of the valve core cannot meet the requirements.

Elimination method: ① Overhaul to make the fit gap meet the requirements; ② Improve the geometric accuracy of the valve core and valve body.

(4) Fault phenomenon: abnormal movement of the spool (hydraulic oil deterioration or oil temperature is too high).

Cause analysis: ①The viscosity of the hydraulic oil does not meet the requirements; ②There is colloid in the hydraulic oil; ③The parts are greatly deformed due to the increase of oil temperature.

Elimination methods: ① Replace the hydraulic oil that meets the requirements; ② Eliminate the cause of excessive oil temperature and filter the hydraulic oil; ③ Avoid the hydraulic oil temperature exceeding the reasonable range.

2. Fault phenomenon of insufficient spool flow: insufficient spool flow.

Reason analysis: ①The elastic coefficient of the spring is too small; ②The gap between the valve body and the valve core is too small to move relative to each other; ③The length of the push rod is small.

Elimination method: ① Replace the spring with the elastic coefficient that meets the requirements; ② Overhaul the gap between the valve core and the valve body to ensure normal relative movement between the two; ③ Appropriately extend the length of the push rod.

3. The hydraulic control reversing valve is not easy to adjust the reversing speed Fault phenomenon: The hydraulic control reversing valve is not easy to adjust the reversing speed (the adjustment device is faulty).

Cause analysis:① There is leakage; ② The type of throttle valve is not suitable; ③ The processing accuracy of throttle valve is low.

Elimination method: ① Replace the seal and fasten the screws; ② Replace the triangular groove throttle valve; ③ Replace the throttle valve with higher processing accuracy.

4. Impact failure phenomenon: impact (commutation impact).

Cause analysis: ① The damping effect is not good or the damping is invalid; ② The electromagnet pulls in too fast.

Elimination method: ①Repair or replace the damping element; ②Adjust the suction speed of the electromagnet.