US Patent 11015687 Linear actuator having free fall function

A linear actuator having a free fall function. The linear actuator moves a piston-rod member back and forth using torque of a rotary motor. Here, the piston-rod member is disposed within a portion of a cylinder body to be movable back and forth. In the event of jamming in which the piston-rod member is stopped due to sticking between an operating nut and a screw member, the piston-rod member is caused to freely fall in a direction in which load is applied. This can consequently obtain the maximum stretched length of the piston-rod member, thereby providing safety in an emergency.