With the hydraulic system moving in the direction of high pressure and high pressure, pilot relief valve extensively used in construction machinery control circuit in the hydraulic system. The use of practice, as to maximize its effectiveness, protection and control system, accurate and timely diagnosis, excluding the pilot-type relief valve failure is the key part.

1, Out of control, leading the host fixed type relief valve failure, the host can lead to action. According to the phenomenon, analysis of reasons: the pilot valve spool spring break; damping hole plug; pilot valve port seals bad; the main spool stuck so. Exclude the corresponding measures are: replacement or additional flat pad in the office break to emergency use; clean dredge; grinding or the oil circuit breaker to emergency use; grinding, cleaning.

2, MOV instability limit of pressure relief valves pilot-type instability, manifested as low or high pressure hydraulic systems, hydraulic actuators action unable or tubing, pump, valve burst. Reasons causing the failure: improper pressure adjustment; pilot valve spool spring bend or soften; oil too dirty or poor oil flow.

Corresponding exclusion measures: re-adjustment; correction, plus pad, or replaced; replacement, cleaning. Pilot-type pressure relief valve limits for the gradual onset unstable failure, and more hours in reserve more motorized construction machinery; pilot-type relief valve failure to sudden failure, and more hours in reserve less motor works machinery. After ruling out complete failure, the machine should be limited by the system pressure on the pilot-type pressure relief valve control to re-adjust.