| 摘要 |
The double-acting piston of a torque wrench has a piston rod, the free end of which receives a pin which is guided at each end in straight or curved guide channels in the wrench housing. The pin passes through drive shoes, slidably received in slots at the upper end of a drive lever. The drive lever as it reciprocates rotates a ratchet wheel, the ratchet wheel having a square central bore to receive a square drive shaft journalled in the housing. If a constant force is applied, the torque wrench provides a substantially constant torque, particularly if the guide channels are curved to compensate for frictional losses. The ratchet mechanism includes rollers which float between grooves in the ratchet wheel and sockets in the drive lever. |
