Specific wrench specifically designed to lock the crankshaft during removal and installation of the central pulley bolt. The wrench allows for greater safety when phasing the timing chain, as the high force that must be exerted on the central bolt of the crankshaft pulley risks damaging both the camshaft tools and the crankshaft pin. of small size. The significant length of the key gives the car repairer the possibility of carrying out the operation independently, By tightening the four fixing screws of the tool in the most appropriate position, exerting the resistance force on the crankshaft flange both manually and by taking advantage of the solid support of the frame, guaranteeing greater strength during the action of loosening or fixing the central bolt.