Abstract: A tool for loosening fasteners, comprises an applicator bar formed with a socket for receiving the fastener to be loosened, a handle fixed to a housing rotatable about the applicator bar for loosening the fastener received in the socket, a hammer within the housing and connected thereto by a spring, and an anvil carried by the applicator bar. The tool further includes a rod coupling the anvil to the hammer in the initial position of the hammer and effective to prevent relative movement therebetween, and thereby to load the spring during the rotation of the operating handle in one direction, and a releasing device effective, after the operating handle has been rotated a predetermined distance, to release the coupling rod, whereby the loaded spring causes the hammer to impact against the anvil to thereby loosen the fastener received in the socket of the applicator bar.