When lever 1 is turned counterclockwise, valve spool 2 is shifted to the right. Then fluid is delivered by gear pump 3 through the groove of valve spool 2 to the right end of cylinder 4, moving piston 5 to the left. Fluid from the left end of cylinder 4 is admitted through pipeline 10 to the right end of cylinder 6, moving piston 7 also to the left. Fluid from the left end of cylinder 6 is discharged through the valve body of spool 2 to the tank. Pistons 5 and 7 continue travel as long as lever 1 turns. The axle of lever 1 is mounted in piston 5. If lever 1 is stopped, it begins to move to the left with piston 5, shifting spool 2 and disconnecting the delivery line of the pump from the right end of cylinder 4. When lever 1 is turned clockwise, spool 2 is shifted to the left and fluid from the pump is directed to the left end of cylinder 6, moving piston 7 to the right. Fluid discharged from the right end of cylinder 6 is delivered through pipeline 10 to the left end of cylinder 4, moving piston 5 to the right. Again, if lever 1 is stopped from turning, piston 5 shifts spool 2 to the right, blocking off fluid delivery to the left end of cylinder 6. Valves 8 and 9 are used to compensate for thermal expansion and leakage of the fluid. If, for example, piston 5 reaches its extreme left-hand position before piston 7 reaches its extreme left-hand position, lug a opens ball valve 8. Then fluid from the right end of cylinder 4 opens valve 9, passes through axial channel b and open valve 8 to the left end of cylinder 4 and then to the right end of cylinder 6, moving piston 7 to its extreme left- hand position. If piston 5 reaches its extreme right-hand position before piston 7 reaches its extreme right-hand position, lug d opens valve 9. Then surplus fluid from the right end of cylinder 6 is discharged through channel b to the tank. This enables piston 7 to reach its extreme right-hand position.
$4223$CHP,Dr$