External spring type heavy power and free function roller

An external spring type heavy power and free function roller comprises a shaft, a roller body and two sealing blocking pieces, the two sealing blocking pieces are arranged at the two ends of the roller body, the shaft penetrates through the roller body and the sealing blocking pieces in the axial direction of the roller body, one end of the shaft is in threaded connection with an adjusting nut, and a pressing piece is fixedly arranged at the end, close to the roller body, of the adjusting nut. The shaft is sleeved with a spring, the two ends of the spring are fixedly connected with the pressing piece and the sealing blocking piece respectively, the other end of the shaft is connected with a shaft sleeve through a bearing, a chain wheel is arranged on the shaft sleeve, a positioning devicecorresponding to the side wall of the shaft is arranged on the inner wall of the shaft sleeve, and a friction piece is arranged between the end, close to the roller, of the shaft sleeve and the sealing blocking piece. Through