Abstract: The invention is concerned with a spark plug wrench with provision for adjustment of the torque, the wrench comprising two toothed discs (2, 3) supported within and at one end of a cylindrical housing (1), these discs being provided at their confronting faces with teeth (5) of a form such that, when screwing-out takes place sharply dependent flanks of opposed teeth are applied together to transmit the full force while, when screwing-in takes place, slippage is allowed between the teeth. In one embodiment the inner lying toothed disc (3) is arranged on an axially displaceable attachment spindle (6) and held against rotation. At the opposite end of the housing (1) is a threaded disc (10) with an adjusting ring (11), and the last-mentioned toothed disc (3) is axially displaceable and has a pack of spring washers (16) thereon to produce the required pressure between the discs (2, 3) for transmitting a pre-set torque.