Fluid is delivered from the system to the upper end of cylinder 1 and into chamber a of the combination (sequence) valve. Piston 2 is moved downward by the action of the fluid, and the fluid from the lower end of cylinder 1 drains back to the tank. Spring 3 of the combination valve is adjusted by screw 6 so that during the stroke of piston 2, valve spool 4 is held by spring 3 in its extreme left-hand position, disconnecting chambers a and d. Check valve 5 is closed. After piston 2 reaches stop 9, pressure increases in the system and spool 4, overcoming the resistance of spring 3, shifts to the right, connecting chambers a and d. At this, fluid from the system is admitted into the left end of cylinder 7, moving piston 8 to the right and discharging fluid from the right end of cylinder 7 to the tank. To return the pistons to the initial position, the direction of the fluid in the system is reversed. Fluid is delivered to the lower end of cylinder 1 and to the right end of cylinder 7, moving pistons 2 and 8 upward and to the left. Fluid from the left end of cylinder 7 flows into chamber d of the combination valve and, opening check valve 5, is discharged to the tank.
$4181$CHP,Dr$