A robotic arm configured to support and operate a surgical instrument includes a slider, first and second nuts rotatably disposed within the slider, a gear, and left-handed and right-handed lead screws. The first and second nuts each have a geared outer surface operably coupled to the gear. The left-handed lead screw extends through the slider and threadingly engages the first nut. The right-handed lead screw is disposed in parallel relation with the left- handed lead screw and extends through the slider. The right-handed lead screw threadingly engages the second nut. A rotation of the left-handed lead screw and/or the right-handed lead screw effects a rotation of the gear relative to the slider or an axial movement of the slider and the gear along the lead screws.
