Importance

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Abstract

The invention relates to a control apparatus for a pneumatic impact wrench driven by an air motor. The pneumatic impact wrench according to the invention comprises a torsion bar, a spindle case, an orifice-shaped rotation suspending valve adapted to narrow or close an exhaust port provided on the torsion bar when the torsion bar is twisted, a pneumatic double-acting main valve adapted to be opened and closed by diaphragms provided intermediately in a passage for supplying compressed air to the air motor, a fluidic element connected to a pilot passage communicating with the control side of the main valve, a conflux pipe and a control valve, the conflux pipe being caused to communicate with one of the control orifices of the fluidic element through a small diameter hole, the other control orifices of the fluidic element being adapted to operate in association with a throttle valve for supplying compressed air to the air motor so as to instantaneously open when the throttle valve opens and closes, thereby communicating with a communication passage leading to the control valve. The torque control apparatus according to the invention is characterized in that two outputs of the fluidic element are caused to communicate with the diaphragms on both sides of the main valve respectively, a second throttle valve being provided in a passage communicating with the input of the fluidic element.

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First Claim