Failure analysis:

     1. The air is mixed with air

     2. Damper hole is sometimes blocked

     3. The roundness of the slide valve and the inner hole of the valve exceeds the regulation, causing the valve to get stuck

     4. The spring is deformed or stuck in the slide valve, making the slide valve difficult to move or the spring being too soft

     5. The ball is not round, the ball does not fit well with the valve seat or the poppet valve is installed incorrectly

     Method of exclusion:

     1. Exclude air in oil

     2. Clear the orifice

     3. Research valve hole and slide valve

     4. Replace spring

     5. Replace steel ball or remove poppet valve adjustment

     Symptom: The secondary pressure is not rising

     Failure analysis:

     1. Leakage

     2. Poor valve and seat bad contact

     Method of exclusion:

     1. Replace seals, tighten screws, and ensure uniform torque

     2. Repair or replace

     Symptoms: Cannot afford to reduce pressure

     Failure analysis:

     1. Drainage port blocked; drain line connected to return line and return pressure

     2. Main spool in the fully open position

     Method of exclusion:

     1. The drain pipe must be separated from the return pipe and returned to the tank separately

     2. Repair and replace parts. Check the oil