A tool for tensioning loosening, and opening spring-type clamping elements with two radially outward-projecting actuating arms, the tool including a hand-operable actuating part, a Bowden cable having a bore and a sheath, the Bowden cable being connected to the actuating part, and a tensioning part with two jaws which are able to move relative to each other. Each of the jaws is configured to act on one of the actuating arms, a first one of the jaws being connected to the core, and a second one of the jaws being connected to the sheath of the Bowden cable so that the jaws can be brought toward each other and thus execute a tensioning movement. The actuating part includes a device for automatically locking in a tensioning stroke and a device for feeding the Bowden cable. The feed device and the locking device of the actuating part are configured to cooperate so that several short tensioning strokes of any desired length can be performed without predefined latching steps, the stroke being locked in place each time until a required total tensioning stroke has been completed.