An end effector of a robotic surgery system that includes a fixed plate for attaching an end of a robotic arm, a shaft extending from the fixed plate, a sliding plate moveable relative to the fixed plate along an axial direction of the shaft, a hub assembly mounted to the sliding plate and operatively engaged with the shaft. The hub assembly includes an idler hub, and an inner bearing moveable relative to the idler hub and operatively engaged with the shaft, whereby rotation of the inner bearing moves the sliding plate along the axial direction of the shaft. The end effector further includes a pulley that includes a driven wheel connected to the inner bearing operatively engaged with a motor, whereby rotation of the driven wheel drives rotation of the inner bearing.
