Fluid-pressure operated tools

摘要

A tool has a housing, a reversible fluid-pressure operated rotary motor which is arranged to drive a bit holder via reduction gear boxes and a clutch which is designed to slip at a predetermined torque. When a trigger is pressed, pressure air is delivered via a valve to the motor, and in a first position of the valve the motor is driven in a forward direction. When the predetermined torque is reached, the clutch slips and displaces an actuator which opens another valve. This in turn creates a pressure differential across the valve which causes it to move to its second position in which pressure air is delivered to the motor to drive it in the reverse direction. When the trigger is released, the valves return to their original positions.