Hydraulic speed control system failure analysis

( 1 ) The main reason for the small feed of the actuator ( hydraulic cylinder , hydraulic motor )

1. The throttle port of the throttle valve is blocked, resulting in no small flow or small flow instability.
2. The spring of the variable speed valve of the variable speed valve is too soft, so that the pressure difference between the front and the back of the throttle valve is too low, resulting in unstable flow through the speed control valve.

3. The pressure reducing valve in the speed regulating valve is stuck, causing the differential pressure before and after the throttle valve to change with the external load. It is often seen that the load is small due to small feed, resulting in an increase in the minimum feed rate.

( 2 ) The main reason for the significant decrease in feed rate when the load increases

1. The leakage of one or several components in the piston or system of the hydraulic cylinder is significantly increased with the increase of load and pressure.

2. The pressure reducing valve in the speed regulating valve is stuck in the open position, and the flow rate through the throttle valve decreases when the load increases.

( 3 ) The main reason for actuator crawling

1. Entering air into the system

2. Due to poor lubrication, the axis of the guide rail and the hydraulic cylinder are not parallel, the sealing pressure of the piston rod is too tight, and the piston rod is bent and deformed, which causes the friction force of the hydraulic cylinder to change greatly during the working stroke and causes creep.

3. In the oil inlet throttle speed control system, the hydraulic cylinder has no back pressure or back pressure, and when the external load changes, the cylinder speed changes.

4. Hydraulic Pump ; the flow pulsation is large, the vibration of the overflow valve causes the system pressure to pulsate greatly, which is caused by the fluctuation of the input pressure oil of the hydraulic cylinder.

5. The valve port of the throttle valve is blocked, the system leakage is unstable, and the pressure reducing valve in the speed regulating valve is not flexible, causing the flow to be unstable and causing creep.