Torque limiting mechanism

摘要

A torque limiting mechanism includes a pulley and a hub. The pulley has a transmission spring. The hub has a groove. A transmission ring is engaged with the transmission spring such that power can be transmitted between the pulley and the hub. The transmission ring includes a coupler block and a coupler. The coupler block is engaged with the transmission spring and the groove. The coupler is connected to the coupler block. The coupler urges the coupler block in a direction disengaging the coupler block from one of the transmission spring and the groove. When the load between the pulley and the hub exceeds a predetermined level, the coupler block is disengaged from the pulley and the hub. Thereafter the coupler keeps the coupler block disengaged from the pulley and the hub. This positively discontinues power transmission according to an applied load and maintains the discontinuation.