Gear pump 1 delivers fluid to variable-displacement pump 2. Surplus fluid is discharged through valves 3 and 4 to the tank. End a of directional valve 5 is connected to the delivery line of gear pump 1. Pump 2 delivers fluid to the right end of power cylinder 6 through valve 5 at whose end d the pressure is equal to that developed by variable-displacement pump 2. Piston 7 is moved by the fluid to the left. Fluid from the left end of cylinder 6 is discharged to the tank after being throttled through the opening formed by the taper of land 8 of the spool of valve 5. Land 9 is of larger diameter than land 8. The spool with lands 8 and 9 is shifted in accordance with the pressure difference at its ends. When piston 7 stops at the end of its working stroke, the pressure in the right end of the cylinder increases and the spool of valve 5 shifts to the left, so that fluid under pressure from pipeline 10 passes through pipeline 11 to a valve (not shown) which reverses the stroke of piston 7.
$4197$CHP,Dr$