CLUTCH

PURPOSE:To obtain a small-sized clutch which can cope with the heavy-load work at a low cost by preventing the first clutch from being disengaged in the heavy-load work, and operating the second clutch to absorb the reaction at the time of locking. CONSTITUTION:When the load torque applied to an output shaft 5 is increased and made larger than the torque to start rotating a main clutch member 10 which is set by the coupling force applied between balls 12 excited by a spring 13 and irregular faces 11 of the main clutch member 10, the main clutch member 10 starts rotating by retreating balls 12 against the spring 13, an internal gear 20 starts rotating, the third-stage planetary reduction mechanism is run idly, and the output shaft 5 is disengaged. For the heavy-load work, the compression of the spring 13 is made maximum by an adjusting handle 6. The reaction of locking by the quick increase of load torque is absorbed by the rotation of the internal gear 20.