A gear mounting structure includes a worm shaft, a gear, and an elastic member. The worm shaft includes a shaft body, on the outer surface of which is formed intersecting spiral grooves, and a gear locking portion with a non-circular cross section, on at least a portion of the outer surface of which is formed a curved surface portion and a planar portion. The gear includes a gear body, on the outer surface of which are formed teeth, and to which the handle rotation is transmitted, and a boss portion protruding from the gear body and having an engagement portion engaging the gear locking portion. The elastic member is mounted so as to abut the outer surface of the boss portion of the gear, and at least a portion of the curved surface portion of the gear locking portion.

The present disclosure relates to a system that uses linear actuators to generate a torque on a shaft. In an example implementation, a system may include a shaft and an attached cam. The cam includes an involute portion. The system also includes a first linear actuator and a second linear actuator configured to move along a first axis and a second axis, respectively. The linear actuators are configured to detachably couple to the cam based on at least a reference angle of the shaft. That is, as the shaft rotates about its rotational axis at the reference angle, the first and the second linear actuators may couple to, and decouple from, various portions of the cam. As the linear actuators couple to, and decouple from, the various portions of the cam, different rotational torques and/or different ranges of such torques may be imparted onto the shaft.

The present disclosure relates to a system that uses linear actuators to generate a torque on a shaft. In an example implementation, a system may include a shaft and an attached cam. The cam includes an involute portion. The system also includes a first linear actuator and a second linear actuator configured to move along a first axis and a second axis, respectively. The linear actuators are configured to detachably couple to the cam based on at least a reference angle of the shaft. That is, as the shaft rotates about its rotational axis at the reference angle, the first and the second linear actuators may couple to, and decouple from, various portions of the cam. As the linear actuators couple to, and decouple from, the various portions of the cam, different rotational torques and/or different ranges of such torques may be imparted onto the shaft.