(57) © A pneumatically driven tool includes a hollow housing (18) in which is located
an air motor including a rotatable motor shaft (20) arranged to drive a tool such
as a screwdriver, socket wrench via a tool drive shaft (22). A torque-sensitive clutch
(24) is located between the tool drive shaft (22) and the motor shaft (20) permitting
the motor shaft (20) to move relative to the tool drive shaft (22) when a predetermined
torque is encountered. A valve (14) located in the housing (18) between the motor
and the air supply source controls the flow of pressurised air to the motor. The valve
(14) is controlled by an elongated valve operating member (54) having a first end
(56) engaging the valve and having a second end (58). A latch member (62) is pivotally
mounted on the tool drive shaft (22) and has a surface (60) thereon that engages the
second end (58) of the valve operating member (54). A hole (76) formed in the latch
member (62) is sized to receive the end of the elongated valve operating member (54).
Normally the hole (76) is not in alignment with the valve operating member (54) and,
thus, the valve (14) is held in the open position. Upon relative rotation as previously
mentioned, the latch member (62) is cammed to a position so that the hole (76) aligns
with the valve operating member (54) permitting the valve (14) to close.
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