SCHRAUB-/LOSSCHRAUBVORRICHTUNG MIT PARALLELEPIPEDISCHER WÄHLVORRICHTUNG

The invention relates to a device for screwing/unscrewing a connection member, that comprises : a casing (30) for receiving a pneumatic engine (32) comprising a cylinder inside which a rotor is capable of rotation for rotatingly driving an end member; a handle (31) connected to said casing (30) and through which extends a means (33) for supplying said engine (32) with a pressurised fluid, and a means (34) for opening/closing said supply means; a means for selecting the rotation direction of said rotor, including a mobile member (36) movable between two positions each corresponding to a different rotation direction of said rotor. According to the invention, the mobile member (36) comprises at least two opposed planar faces (365, 366) that can be respectively pressed against a first bearing surface (322) formed on said cylinder and a second bearing surface (373) formed on a piston (37) movable along said supply means (33), said piston (37) being capable of pressing said mobile member (36) onto the first bearing surface (322).