| 摘要 |
A portable pneumatic tool e.g. a fastener tightener includes a valve closure sleeve 66 interposed in the tool motor exhaust passage 38, 40 and engaged with a speed responsive mechanism comprising a plurality of flyweights 64 operable to move the closure sleeve 66 away from a seat 70 on starting of the tool motor. On decreasing motor speed due to high reaction torque a coil spring 72 assisted by a fluid pressure drop across the closure sleeve 66 forces the closure sleeve to move against the decreasing centrifugal force exerted by the flyweights 64 to seat the sleeve to shut off motor exhaust fluid flow, stopping the motor. The closure sleeve 66 is normally held in a partially open position by a spring washer 80 to enable the motor to be started. <IMAGE> |
