When compressed air is delivered to port 1, piston 2 is advanced by the air pressure with spindle 3 to the work. Hydraulic fluid is forced out from the other side of the piston through valve 4 which is closed after piston 5 has advanced a certain distance. After valve 4 is closed, the hydraulic fluid can escape only through flow-control valve 6, whose clear opening regulates the rate of spindle feed. After machining the work, port 1 is connected to the atmosphere. Then spring 7 returns pistons 2 and 5 rapidly to the initial position, retracting the spindle. The hydraulic fluid is forced back into the left chamber through check valve 4 which is opened by the pressure of the fluid.
$4205$CHP,Dr$