APPARATUS FOR TIGHTENING THREADED FASTENERS

According to a first aspect of the invention we provide a low clearance face tooth ratchet assembly for link drive means of hydraulic torque tools. The face tooth ratchet assembly includes: a drive plate having piston engagement means at a first end and a machined face gear with radial serrations at a second end; and a ratchet drive having a machined face gear with corresponding radial serrations at a first end and a threaded fastener engagement means at a second end. Advantageously the low clearance face tooth ratchet assembly minimizes volume and mass of the tool. Only one drive plate is necessary which is tapered from a first end to a second end. Further, side plates of the link drive means are tapered from a first end to a second end. Such geometry minimizes the width of portions of the link drive means making the second end, adjacent the threaded fastener engagement means, substantially thinner than the first end, adjacent the piston engagement means. Higher torque values are transferred in a smaller enclosure via only two parts. Notably no drive and/or reaction pawl is necessary as the teeth of the drive plate and the ratchet drive achieve full facial engagement. The design of the connection coupling is backlash-free, maximizes tool safety, minimizes risk of failures/fatigue from wear, bending, scuffing and cracking, and is suitable for changing forces.