| 摘要 |
A power unit for use with a jack stand and a lift bridge has a rectangular frame with a forward end having a pair of separated elongated extensions for supporting the jack stand. The extensions extend about 1.50 inches beyond the latch finger of a positioned jack stand. A pair of side flanges extend upwardly from the frame with a "U" shaped retaining channel attached horizontally therein. A pair of lift arms are interconnected at the rearward ends by a lateral push bar that slides within the retaining channels by the ram of a hydraulic cylinder. A pair of connecting arms are pivotally connected near the forward end of the frame and the central portions of the lift arms. The forward ends of the lift arms have a pair of frusta-conical discs for self-aligning engagement with the lower ends of the lifting plate of the jack stand. The power unit includes a lift bridge for positioning at the forward ends of the lift arms. The power unit has a tubular handle with T bar hand grip, rotatable knob for controlling the cylinder, and a control lever at the proximal end, and a yoke at the distal end pivotally attached to the rearward end of the frame. The yoke includes a cylindrical disc with peripheral notches therein that are engageable by a lug on a foot operated handle for controlling the position of the tubular handle of the power unit. The commercial power unit further includes a safety mechanism for mechanically securing the lift arms in an elevated position, and that is releasable by the control lever.
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