Development of a passively operating load-responsive transmission

A passively operating load-responsive transmission capable of switching the reduction ration in response to load-torque was developed. When the load torque is low, the transmission operates with a low reduction ratio that enables the actuator to rotate a high-speed and low-torque load efficiently. When the load torque increases, the transmission switches to a high reduction ratio to rotate a low-speed and high-torque load. The reduction ratio is switched by a pair of clutches connected and disconnected separately. These clutches are passively operated by the magnetic mechanism that exerts thrust in alternative direction responding to the load torque without any accessory actuators, sensors, electronics or power supplies. The load-responsive transmission can reduce power, size and weight of the mechanical system and improve its safety since a variant load can be actuated efficiently by a minimal actuator. In this paper, the advantages and requirements of the load-responsive transmission are first outlined followed by the structure and the operation of the developed transmission. Further, the characteristics of a prototype transmission are experimentally evaluated.