Importance

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Abstract

A compressed air driven hand-held tool including a body adapted to be grasped by the hand, an air inlet adapted to be connected to an air supply hose, an air motor driving an output shaft carrying a work implement, and a throttle valve controlling the supply of air to the motor. A spring acts on a valve piston to urge the throttle valve to a closed position. The piston is acted on by air pressure to allow the throttle valve to open. A control chamber in the tool body receives air pressure from the air supply through a restricting orifice at a controlled rate, has an air outlet adapted to closed by the hand of the operator when grasping the tool body and is connected to the air pressure side of the valve piston. When uncovered, the air outlet exhausts the air in the control chamber at a rate to maintain the pressure in the control chamber at an atmospheric level. When covered by the operator's hand, the air pressure in the control chamber rises and acts on the valve piston to open the throttle valve. A second embodiment includes a two-stage valve circuit for controlling the air motor.

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First Claim