Pump 1 delivers fluid through pilot-operated directional valve 2 to the upper end of cylinder 3, and piston 4 moves downward. The lower end of cylinder 3 is connected to the delivery line. Valve 2 is controlled by rotary pilot valve 6. At the end of the stroke of piston 4, a trip dog mounted on the travelling head of the machine tool turns valve 6, and fluid under pressure from the delivery line passes through the valve and ball check valve 7 to the left end of valve 2, shifting its spool to the right, while fluid from the right end of valve 2 drains through flow-control valve 5 and valve 6 back to the tank. In this position of the spool of valve 2, fluid is delivered by the pump to the lower end of cylinder 3 and the upper end is connected through valve 2 to the tank. Piston 4 moves upward. The speed of piston 4 is varied by a speed regulator installed in the delivery line of the system and consisting of flow-control valve 11 and pressure reducing valve 8 which automatically maintains a constant pressure before valve 11. The system is started and stopped by valve 9 which connects the delivery line to the tank to stop the machine tool. Relief valve 10 protects the system against overloads.
$4193$CHP,Dr$