Patent ID: 6530219
Filing Date: 2003-03-11
Classification: B66F

Abstract:
A jack assembly that may be lifted rapidly, comprising: a base, a push seat, and an outer cylinder and an inner cylinder mounted between the base and the push seat, an inner oil chamber formed in the inner cylinder, an oil storage chamber formed between the outer cylinder and the inner cylinder, a lifting column mounted in the inner cylinder, and having a distal end provided with a piston, the base provided with a main oil path, and having an end face provided with an oil suction hole connected to the oil storage chamber and connected to a lower end of the main oil path, an anti-reverse ball mounted in the lower end of the main oil path to block the main oil path, and is pushed by a post, an oil hole located above the anti-reverse ball being formed in the inner wall of the main oil path, and connected to a return oil path; wherein:a lower ball is mounted in a mediate portion of the main oil path, and is pushed by a first spring, an upper end of the first spring is provided with an upper ball, the upper ball is provided with a push post which is pushed by a second spring, an upper end of the second spring is pushed by an adjusting screw, the main oil path has an inner wall formed with a first oil hole that is located above the lower ball, the first oil hole is connected to an oil hole of a center of a secondary shaft that is mounted in the lifting column, the inner wall of the main oil path is formed with a second oil hole that is located above the upper ball, and is connected to the inner oil chamber; and wherein: hydraulic oil in the oil storage chamber pushes away the lower ball, so that the hydraulic oil may flow through the first oil hole into the oil hole of the secondary shaft, the hydraulic oil may push the lifting column by means of a smaller cross-sectional area of an axial hole for receiving the secondary shaft, so that the lifting column that has not worked may be lifted rapidly, thereby shortening the working stroke, when lifting of the lifting column is stopped, the lifting column works and a pressure of the hydraulic oil of the main oil path is increased largely, whereby the upper ball is pushed away, so that the hydraulic oil flows through the second oil hole into the inner oil chamber of the inner cylinder, the inner oil chamber of the inner cylinder has a larger cross-sectional area, so that the lifting column may have a sufficient lifting force to lift an object.