Abstract: A system and method for compensating for torque overshoot in a rotary power tool wherein the tool is shut off at an adjusted set point value of torque which is below the target value of torque by the amount of torque overshoot. While the tool is operated to perform a fastening job, the relationship between the torque rate in the fastening job to overshoot in the tool is determined, the torque rate in the job is monitored while the tool is setting the job, and the torque set point is adjusted while the tool is setting the job to compensate for the torque overshoot determined from the foregoing relationship.

Abstract: A trigger for a fluid operated tool has a control with a pilot valve which when open pressurizes a chamber to cause a throttle valve to open. When closed, the pilot valve restricts fluid flow and reduces fluid pressure in the chamber, permitting the throttle valve to be closed. A continuously variable trigger control is also featured for varying the fluid flow rate to the tool.

Abstract: A power drive control unit of a torque control clutch for a fluid operated power tool features a latch, operable for initiating and interrupting motive fluid flow to a rotary fluid motor, and an actuator pin for controlling the latch. The latch is carried on a drive spindle rotatable in synchronism with a driven clutch part and is supported for rotation on that drive spindle. The actuator pin is carried on a driving clutch part for actuating the latch upon relative movement between the driving and driven clutch parts at a predetermined output torque for moving the latch into position to interrupt fluid flow to the motor within less than a single revolution of relative movement between the driving and driven clutch parts.

Abstract: The air tool of this invention features a shut-off valve in a motor inlet passage with an air bias compartment at one end of the valve and a motor pressure compartment at an opposite end of the valve directly communicating with the inlet to the motor. The air bias compartment has adjustable air bleed means for selectively reducing the pressure in the air bias compartment from a predetermined line pressure to a desired operating pressure at a constant percentage less than the predetermined line pressure. To establish the predetermined line pressure of the air supplied to the motor and to the air bias compartment of the shut-off valve, a stall torque regulator is provided upstream of the shut-off valve. This regulator serves to maximize the flexibility of the tool by providing for the adjustment of the tool to a given range of pressure and torque at which the motor will shut off but without undesirably affecting the free running speed of the motor within that given range.

Abstract: A system for measuring torque applied by an air tool to a fastener during a fastening operation is disclosed wherein a torque indicating device is provided, preferably in a remote position from the tool, for sensing and indicating the torque applied to a fastener by the tool. In the preferred embodiments, an air pressure signal transmitter is connected between a motor inlet air passage and the torque indicating device for supplying a continuous air signal, indicative of fastener torque applied by the tool, to the torque indicating device during operation of the air tool.