Hydraulic jack

摘要

A hydraulic jack suitable for powering a large load such as an elevator or a drawbridge. In a first embodiment the hydraulic jack telescopes at a uniform rate over its entire distance of extension and includes a plunger member telescopingly enclosed within a sleeve member which, in turn, is telescopingly enclosed within a cylinder member, with the cylinder member encircled by an oil jacket within which the cylinder member is capable of limited angular movement. Means are provided for angularly aligning the various members within one another. Means are also provided to restrict the flow of hydraulic fluid as the hydraulic jack reaches a limit of its travel. Hydraulic jacks in accordance with the present invention can be coupled together in systems to lift large loads.