| 摘要 |
In a pneumatically driven power torque wrench comprising a frame stopped from movement relative to a related structure, a hydraulic cylinder and ram unit carried by the frame, a work output shaft rotatable relative to the frame and coupled with work to be turned in axial alignment therewith, a lever arm with one end freely rotatably engaged about the shaft and its other end drivingly coupled with the cylinder and ram unit; and ratchet means between the shaft and lever arm. The ratchet means comprises a ratchet wheel about the shaft and a plurality of circumferentially spaced spring-loaded pawls pivotally carried by the lever arm and engaging the wheel. The shape and the circumferential spacing of the teeth on the wheel and the pawls are such that when rotary driving engagement is established between the shaft and the lever arm, the central rotative axes of the work, shaft and said one end of the crank are concentric, independent of any bearing support between the shaft and the frame.
|
