Loader excavator accessories 375-4414 Hydraulic valve

The common faults are that the solenoid valve does not work, which should be checked from the following aspects:

1. The solenoid valve connector is loose or the wire connector is off, the solenoid valve is not electric, and the wire connector can be tightened.
2, the solenoid coil is burned out, you can remove the solenoid valve wiring, measurement with a multimeter, if open, the solenoid coil is burned out. The reason is that the coil is damp, causing poor insulation and magnetic leakage, causing the current in the coil to be too large and burned, so it is necessary to prevent rain from entering the solenoid valve. In addition, the spring is too strong, the reaction force is too large, the coil turns are too few, and the suction is not enough can also make the coil burn. In case of emergency, the manual button on the coil can be pressed from the "0" position in normal operation to the "1" position to make the valve open.
3, the solenoid valve stuck: the solenoid valve sleeve and the spool with a small clearance (less than 0.008mm), is generally single
Part assembly, when there are mechanical impurities or too little lubricating oil, it is easy to get stuck. The treatment method can be steel wire through the small hole of the head to make it spring back. The fundamental solution is to remove the solenoid valve, take out the spool and spool sleeve, and clean it with CCI4, so that the spool is flexible in the valve sleeve. When disassembling, attention should be paid to the assembly sequence and external wiring position of each component, so as to reassemble and wire correctly, and check whether the oil spray hole is blocked and whether the lubricating oil is enough.

The drive is different. The driving device of the proportional valve is the proportional electromagnet, and the driving device of the servo valve is the force motor or the torque motor, and the performance parameters are different. Hysteresis, middle dead zone, bandwidth, filtration accuracy and other characteristics are different, so the application occasions are different, servo valves and servo proportional valves are mainly used in closed-loop control systems, proportional valves of other structures are mainly used in open loop control systems and closed-loop speed control systems.
The input power of the general proportional valve is large, basically in the hundreds of Ma to 1 amp or more, and the input power of the ordinary valve is relatively large
Small, basically in tens of MA; The control accuracy of the proportional valve is slightly lower, the hysteresis is larger than that of the servo valve, and the control accuracy of the ordinary valve is high, but the requirements for the oil are also high.
It is understood from the structure that the spool of the proportional valve is balanced by electromagnetic force and hydraulic pressure and spring force, while the ordinary valve is balanced by hydraulic pressure, so the proportional valve has no advantage in controlling large flow and high pressure. There are proportional valves early products are open, which should be the reason why they are called proportional valves.