Power main shaft unit of hydraulic clamp

The utility model discloses a hydraulic clamp power main shaft unit which comprises an outer box body, a workpiece is installed in the outer box body, a pull pipe is arranged on the workpiece in a sleeved mode, and a first elastic chuck and a second elastic chuck are arranged at the two ends of the workpiece in a sleeved mode respectively. One end of the pull pipe is sleeved with a piston, the piston is connected with a first elastic chuck, the piston is sleeved with a main shaft, one side of the main shaft is provided with a first valve element, and the side, opposite to the first valve element, of the main shaft is provided with a second valve element; a first oil inlet is formed in the first valve element and communicates with the right end of the piston. A second oil inlet is formed in the second valve element and communicates with the left end of the piston. The hydraulic locking device has the advantages that the defect of friction temperature rise of hydraulic oil caused by continuous oil supply can be