The bucking unit have been designed to make and break screwed connections with high torques. The unit is a combination of a KOLLER hydraulic vice 220 kN and a hydraulic operated chain tong. For the basic unit without electronic data logger, no electrical supply is required. Both, the hydraulic vice and the tong are supplied by pressure air driven hydraulic power packs. Since the bucking unit is mounted on a solid steel frame with forklift truck pockets, it is transport friendly and can be moved easily on site.