| 摘要 |
There is disclosed a torque wrench, including a main body, an actuator including a piston/cylinder arrangement and cooperating spool valve which selectively supplies pressurized fluid to either side of the piston member. The actuator is supported in the main body and adapted to act upon and selectively reciprocate a thrust member relative to the main body, the thrust member being adapted to engage and pivot a torque arm for providing a torque output at an output shaft via a ratchet arrangement incorporated between the torque arm and the output shaft. The torque arm is supported independently of the thrust member and is not physically connected thereto. The exposed area of the piston member on a return side thereof is relatively smaller than the exposed area on the opposite or power side thereof, whereby the swept volume during a return stroke is relatively smaller than the swept volume during a power stroke, to thereby produce a low force relatively high speed return stroke and a high force relatively low speed power stroke. A return spring biases the torque arm to a home position during a return stroke of the piston member. The torque arm has a curved surface adapted for engagement by a correspondingly curved surface on the thrust member to maintain high force transmitting area contact as distinct from point or line contact. Means are also provided to measure the amount of rotation of the output shaft to allow utilization of the "turn of nut" technique often used with torque wrenches. |
