A retractor includes a slide nut that is caused to slide toward a tread head while rotating by a mesh between a first male screw groove and a female screw groove when the tread head is locked and a spindle rotates in a direction for unreeling a webbing, and a slider that is caused to slide toward the slide nut by a mesh between the female screw groove and a second male screw groove. The suspension device in its most general form comprises a support element and an attachment element. The systems and method are applicable to, and reliable for various memory technologies, since the size of the steps or other such functional transitions of the ramped voltage profile can be adjusted or trimmed to any level of resolution required. A second drive mechanism is rotatably mounted at the distal end of the support member and coupled with the first drive mechanism. The system includes a support system operably vertically supporting the hopper support vertically movably independent of the row unit frame. Therefore, deformation of the internal gear member 24 is effectively restricted.