Abstract: A power unit (or a hydraulic floor jack) includes a rectangular frame with side flanges and has a tubular handle enclosing a control shaft and a control knob. A pivotal lifting mechanism is mounted on the frame including a pair of parallel lift arms having rearward ends interconnected by a lateral push bar. The forward ends (with the bridge) are rotatable upward for lifting a load as the push bar is translated forward within a pair of U channels tracks attached to the inner side flanges. A hydraulic cylinder has a ram for pushing the lateral push bar forward along the tracks for raising the forward ends of the lift arms, and has a releasable control valve for retracting the ram to lower the forward ends of the lift arms. The safety mechanism includes a toothed rack bar secured in the vertical wall of the racks. The lateral push bar has bore holes in the ends thereof.