Automatic fluid torque responsive shut-off mechanism for an air tool

In a fluid driven tool of the type having a housing a fluid driven motor with a rotary shaft defining an axis, a fluid inlet passage to the motor, and a fluid control valve mechanism in the inlet passage, the improvement comprising:

• an automatic fluid shut-off mechanism in the inlet passage responsive to acceleration and speed, said mechanism including:
• a guide member keyed to the rotary shaft for rotation therewith, said guide member having a face with at least one guide groove, said groove defining a path which intersects a radius extending from the axis
• an element slidable in the guide groove between an inner position adjacent the axis and an outer position in response to acceleration forces thereon,
• a plate member defining a cam surface positioned against the slidable element and movable generally parallel to the axis in response to movement of the element in the groove against the cam surface;
• said plate member movable between a first position corresponding to the inner position of the element and a second position corresponding to the outer position of the element;
• a main valve member connected to the plate member in the inlet passage;
• a main valve seat cooperative with the main valve member to close the inlet passage whenever the plate member and attached main valve member are moved to the first position and to otherwise open the inlet passage;
• and
• a manually operated fluid inlet and bypass valve mechanism to initially bypass the main valve member and direct pressurized fluid directly to the motor to initiate operation of the motor, said fluid inlet and bypass valve mechanism including:
• a manually operable inlet valve assembly with a first valve upstream from the main valve member in the inlet,
• a parallel fluid passage connecting the inlet passage directly to the motor from the downstream side of the first valve;
• a second pilot valve, said second pilot valve normally closing the parallel fluid passage and having its downstream side directly in communication the fluid motor, the upstream side of the pilot valve connected through a flow control orifice to the inlet passage downstream from the first valve, whereby a differential pressure results on opposite sides of the pilot valve to operate the pilot valve initially upon actuation of the manually operable inlet valve to the open position for fluid to flow directly to the motor, and subsequently to switch the pilot valve to the closed position after the motor has operated at a sufficient speed to effect opening of the main valve member by cooperation of the slidable element on the cam surface.