Abstract: A hydraulic vehicle jack including a novel release valve is disclosed. The jack is of the type having a high pressure cylinder, a ram partially extensible from and retractable into the cylinder, and a high pressure pump for forcing fluid from a reservoir into the cylinder to extend the jack. When it is desired to lower the jack, the release valve needle is turned so as to withdraw a needle tip from fluid-flow-halting engagement with a valve seat. This needle tip is formed in the shape of a cone having an altitude of a dimension greater than the cone base radius. When the needle tip is withdrawn from its position against the valve seat, a small but precisely defined fluid-flow-permitting orifice is created. Valve lowering action then occurs over an extended time period which permits the jack operator to precisely control or halt valve lowering action as desired.

Abstract: A hydraulic jack is disclosed, of the type comprising a ram having a head portion reciprocable in a cylinder between two cylinder ends, and sealing means carried on the ram head portion to provide a substantially fluid-tight seal between the ram and the cylinder interior surface. In this jack, an open sided pressure relief trough is formed in the interior surface of the cylinder adjacent one end to permit the flow of fluid past the sealing means when the head portion is located substantially adjacent the cylinder end and relief trough. Fluid bleeding action past the relief trough thus prevents forcing the ram head and sealing means against the cylinder end. When the jack is so constructed, the sealing means can include an elastomeric seal cup member which will not be damaged by its travel past the trough.

Abstract: A tiltable jack is provided. A cylindrical pivot pin is disposed between a jack housing and a base member. A bowed leaf spring urges the jack housing toward and into an upright position. Tangs on the spring and abutments on the base member retain the pivot pin in a desired location.

Abstract: The embodiment of the invention disclosed herein is directed to a lifting jack having an upstanding hollow strut member for rotatably receiving a screw rod therein. The strut member has a flat front wall which forms a glide surface and inwardly turned portions to form a rear glide surface. The inwardly turned portions are spaced apart to provide a longitudinal opening through which extends a slide member secured to a load-lifting support element. The upper end of the screw rod is provided with a non-circular configuration having flat side wall portions and shoulder portions extending therefrom to be inserted into a recess formed in a washer which is to rotate therewith. The washer bears against a pair of thrust disks which are positioned between the upper end of the strut member and the washer. The thrust disks provide multiple thrust bearing surfaces for increased wearability and ease of turning under heavy loads.