PC300-5 PC400-5 Control main valve 709-90-52203 relief valve

Excavator solenoid valve structure
Solenoid valve includes coil, magnetic core, ejector rod, the general spool can be in the coil electromagnetic force driven sliding, the spool in different positions, the path of the solenoid valve is different. There are several working positions of the spool, which are called several solenoid valves; The valve body has several passages, which are called solenoid valves. Some solenoid valves are powered for a long time, and some are powered for a short time. For example, when the excavator is not started, the GPS is always powered on when the negative main switch is not turned off; Safe locking solenoid valve is always in operation
Electrified; The two-speed solenoid valve is powered on when the rabbit is selected. The excavating booster solenoid valve is powered on for a short time when the contact booster switch is switched on.

Excavator hydraulic pump (main pump) solenoid valve
At present, for the Japanese KAWASAKI hydraulic components, the hydraulic oil pump suitable for medium and large excavators is generally composed of a double pump with a swash plate variable piston and a pilot gear pump in series before and after, and a set of proportional solenoid valves are selected to control the Psv current, because the hydraulic servo control has a certain delay, and the electronic control is very fast to make up for the defects of the regulator. For example, when the excavator suddenly encounters a high load, the regulator is too late to quickly reduce the flow of the hydraulic pump, which may cause the excavator to stall and the actual engine speed to decrease, while the proportional solenoid valve senses the engine speed lower than the engine throttle in the engine speed sensor
When the speed is fast, it can be quickly opened, and the flow of the hydraulic pump can be rapidly reduced by the pilot pressure to ensure that the engine will not stall.