An assembly jig comprises: a support member providing a support surface; a tool configured to receive one component of a faster pair such that the component is not rotatable relative to the tool; one or more alignment members to locate the tool relative to the support member; wherein the one or more alignment members and the tool are configured such that, when the tool is located by the one or more alignment members on the support member, the tool is still rotatable with respect to the support member about an axis perpendicular to the support surface.

A screwing/unscrewing tool for screwing/unscrewing a screw or a bolt includes a first part including a lever secured to a screwing/unscrewing bit provided with at least one screwing/unscrewing recess centered on a main axis, a second part including a support arm equipped with a tapped hole and on which the screwing/unscrewing bit is rotatably mounted around the main axis, and an adjustment screw screwed into the tapped hole and having a coupling head configured for a coupling with a screw-gun or a wrench, and extended by a threaded rod having a free end suitable for abutment on the lever in order to apply a pivoting force to it. The screwing/unscrewing tool may be used with a screw or bolt that is difficult to access in a crane mast or crane jib.

An anti-slip torque tool that utilizes a plurality of grooves to prevent slippage and facilitate torque transfer to a fastener. The tool includes a wrench torque-tool body and an at least one engagement element. The wrench torque-tool body includes a plurality of internal sidewalls, a first base, and a second base. Further, each of the internal sidewalls includes a bracing surface. The engagement element includes at least one first groove and at least one second groove, wherein each further includes a primary cavity and a secondary cavity. The engagement element is laterally integrated into a specific sidewall to provide additional gripping action. The first groove and the second groove are positioned offset from each other, along the bracing surface of the specific sidewall. The primary cavity and the secondary cavity each traverse normal and into the bracing surface from the first base to the second base.