A hand held pneumatic tool is provided for driving fasteners in which the
cam shape and arrangement between the driving and driven cams provides a
"dwell" time for preventing further impacts after the desired torque has
been reached and a latch arrangement provided to prevent undesired
shut-off in the reverse direction of operation. Means are provided to
assure restart after shut-off, and a ball spline between the driven cam
and spindle is used to increase accuracy.
