Abstract: A hydraulically-powered tightening and loosening spanner includes a ratchet wheel assembly, a retaining mechanism, a drive lever connected to a piston rod and fixedly supporting a guide, and a member rotating the ratchet wheel assembly and including a slide which supports one or more drive elements and is slidable along the guide during reciprocal motion of the piston.

Abstract: Method for controlling a pressurized fluid-actuated double acting cylinder in an assembly such as a hydraulic tightening spanner (1) with a control unit therefor, wherein a piston (5) may be reciprocated repeatedly, firstly with an active stroke providing a desired maximum force, and then with an opposed passive stroke returning the piston (5) to its starting point to enable repetition, and wherein said method comprises selecting a set fluid pressure corresponding to the desired maximum force (Fr) and measuring the time elapsed (Te) between the beginning and the end of the passive return stroke to determine that the force has been achieved. A device for implementing the force is also disclosed.