The valve and the automated parts are all in the off-position in this drawing,
When open valve, solenoid directional valve 4DT get electricity, the electrical motor starts, the pressure oil in the oil pump enters the servomotor down cavity, push the piston rod to overhang, at the same time hold the heavy bob, the solenoid direction valve 6DT get electricity then the change pressure oil enters the locking oil tank down cavity push piston rod to overhang then to lock. remove lockin, the solenoid directional valve 3DT get electricity, pressure oil in power accumulator enters the locking oil tank up cavity When close valve the solenoid directional valve 3DT get electricity, pressure oil in power accumulator enters servomotor up cavity. Push the piston rod indentation, closes the valve under servomotor and the heavy bob function.