When the hydraulic motor is switched on, fluid under pressure is delivered to spools 1 and 2. A part of the fluid, passing through a groove of pilot spool 2 and passage 5, is delivered to the left end of main spool 1, holding it in the right-hand position. The main stream of fluid passes through another groove of spool 2 and passage 6 to the right end of motor cylinder 7, moving piston 3 to the left. At this, the piston rod pushes pin 8, turning lever 4 about fixed axis A and shifting pilot spool 2 to the right. At this, fluid under pressure is delivered through passage 9 to the right end of spool 1. From the left end fluid passes through passage 5 to the drain pipeline. In the extreme left-hand position o spool 1, fluid passes through passage 10 to the left end of cylinder 7; piston 3 moves to the right and fluid from the right end of the cylinder drains to the tank through passage 6 and a groove of spool 1.
$3953$LHP,Dr$