| 摘要 |
A rotary impulse tool has a motor-driven drive shaft and an output shaft. The drive shaft is threadedly coupled to a flywheel sleeve, which is spring-biased forwardly and is splined to a rotatable race structure of a wrap spring clutch assembly, which includes a wrap spring disposed in clearance fit coaxially between cylindrical surfaces of the race structure, the wrap spring having a front end fixed to the output shaft and a rear end coupled to a first conical control member. A second conical control member is axially movable between engaged and disengaged positions relative to the first control member for, respectively, shifting the clutch assembly to an engaged condition for transmitting torque between the drive and output shafts and a disengaged condition for decoupling those shafts. When the clutch assembly is engaged, the drive shaft rotates the output shaft and, as torque builds up on the output shaft, it slows to develop a speed differential between the drive and output shafts, which retracts the flywheel sleeve rearwardly against a compression spring to engage the second control member and move it axially to its disengaged position for disengaging the clutch assembly, whereupon the flywheel sleeve rapidly rotatably and axially returns forwardly, engaging the second control member to move it back to its engaged position and reengage the clutch assembly to transmit the kinetic energy of the flywheel sleeve in an impulse to the output shaft.
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