Excavator solenoid valve TM70402 24V hydraulic pump proportional solenoid valve

 Excavator electromagnetic relief valve fault and troubleshooting method:

1. System pressure fluctuation

The main causes of pressure fluctuations are:
① The screws adjusting the pressure cause the locking nut to loosen due to vibration, resulting in pressure fluctuation;
② Hydraulic oil is not clean, there is a small dust, so that the main spool sliding is not flexible. Resulting in irregular pressure changes. Sometimes the valve will jam;
③ The main valve spool is not smooth, causing the damping hole to be blocked when it is through;
(4) The conical surface of the main valve core is not in good contact with the cone of the valve seat, and it is not well grinded;
⑤ The damping hole of the main valve core is too large and does not play a damping role;
The pilot valve adjusting spring bending, resulting in poor contact between the spool and the cone seat, uneven wear.
The solution:
① Clean the oil tank and pipeline regularly, and filter the hydraulic oil entering the oil tank and pipeline system;
(2) If there is a filter in the pipeline, the secondary filter element should be added, or the filtration accuracy of the secondary component should be replaced; Disassemble and clean the valve components and replace the clean hydraulic oil;
③ Repair or replace unqualified parts;
④ Reduce the damping aperture appropriately.

g, rubber ring wear and not timely replacement.

System pressure can't go up at all

Reason 1:
① The main spool damping hole is blocked, such as the assembly of the main spool is not cleaned, the oil is too dirty or the assembly with debris;
② Poor assembly quality, poor assembly accuracy during assembly, poor adjustment of the gap between valves, the main spool stuck in the open position, poor assembly quality;
③ The main spool reset spring is broken or bent, so that the main spool can not be reset.
The solution:
① Disassemble the main valve cleaning damping hole and re-assemble;
② Filter or replace the oil;
③ Tighten the valve cap fastening screw to replace the broken spring.

Cause 2: The pilot valve is faulty
① The adjusting spring is broken or not loaded,
② Taper valve or steel ball is not installed,
③ The taper valve is broken. Solution: Replace the damaged parts or replace the parts to restore the pilot valve to normal work.

Cause 3: The remote control port solenoid valve is not powered on (normally open) or the slide valve is stuck
Solution: Check the power line to see if the power supply is connected; If normal, it indicates that the slide valve may be stuck, and the faulty parts should be repaired or replaced.