Rear pneumatic chuck

The rear pneumatic chuck comprises a base and a rotating body rotationally installed on the front side of the base, four air cylinders are evenly and fixedly installed at the rear end of an inner cavity of the rotating body in the circumferential direction, and the piston ends of the air cylinders are connected with transmission assemblies respectively. Four sets of clamping jaw assemblies connected with the transmission assemblies are evenly arranged on the front side of the rotating body in the circumferential direction. A rotation driving device suitable for driving the rotating body to rotate is arranged at the rear end of the base, and a sliding ring assembly communicated with the air cylinder and an external air source is arranged at the rear end of the rotation driving device. A traditional square air cylinder is replaced by the air cylinders, so that the overall outer diameter after the four sets of air cylinders are assembled is reduced, an air cylinder assembly with the reduced outer diameter is mov