Importance

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Abstract

A vehicle jack comprises a base with means for moving the jack smoothly on a ground, an upright shell located on the base, an upright hydraulic ram located inside the shell and including a cylinder construction and a hollow rod, a vehicle support for directly supporting the bottom of a vehicle to be jacked up, a hydraulic source for raising the cylinder construction, and a locking means for mechanically preventing the cylinder construction from lowering from a raised position. The cylinder construction may include an outer cylindrical wall, an intermediate, slidable cylindrical wall capable of being extended upwardly from the rest of the cylinder construction and having openings through any one of which a pin may be inserted to fix the intermediate cylindrical wall at a required height, and an inner cylindrical wall defining an inner cylinder chamber. The hollow rod is located inside the inner cylindrical wall, and is fixed to the base at its bottom and defines an inner oil path which is in communication with the cylinder chamber. The hydraulic source is in communication with the oil path and supplies a hydraulic oil through the oil path into the cylinder chamber to raise the cylinder construction to lift up a vehicle with the vehicle support. The locking means, for example, may comprise a thread formed on an outer circumference of the outer cylindrical wall of the cylinder construction and an annular stopper provided around the outer cylindrical wall and having at an inner surface thereof a thread which is in engagement with the thread on the outer cylindrical wall.

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First Claim