Two-speed hydraulic cylinder and lifting mechanism applying same

Abstract

The invention provides a two-speed hydraulic cylinder and a lifting mechanism applying the same. The invention relates to the two-speed hydraulic cylinder and the lifting mechanism, wherein the hydraulic cylinder comprises a cylinder body and a piston movably arranged in the cylinder body; an oil channel, a fast hole and a damping hole are arranged at the bottom of the cylinder body; the oil channel is used for being communicated with an external oil way; the cylinder body comprises a motion chamber for allowing the piston to do piston motion; the two ends of the fast hole and the two ends of the damping hole are communicated with the oil channel and the motion chamber respectively; the end of the fast hole, which has a large diameter, is communicated with the motion chamber; the hydraulic cylinder further comprises a limit valve rod and an elastic piece, and the limit valve rod is opposite to the fast hole; the end, accommodated in the motion chamber, of the limit valve rod is provided with a blind hole; the elastic piece and part of the limit valve rod are accommodated in the blind hole; and the other part of the limit valve rod extends out of the blind hole under the elastic action of the elastic piece. During the oil return process of the hydraulic cylinder, when the limit valve rod is not propped against the fast hole, the hydraulic cylinder returns oil simultaneously through a fast channel and a slow channel, and when the limit valve rod is propped against and seal the fast hole, the hydraulic cylinder returns oil only through the slow channel.

Description

Technical field [0001] The invention relates to a two-stage speed hydraulic cylinder, and in particular to a two-stage speed hydraulic cylinder used in a lifting mechanism. Background technique [0002] Lifting mechanisms (such as vehicle cranes) generally include hydraulic cylinders used to provide lifting power to the lifting mechanism. During the advancement and reset process of commonly used hydraulic cylinders, the running speed of the piston rod generally remains unchanged, that is, the piston rod only has the ability to run at a single speed. Therefore, when the lifting mechanism needs to descend quickly in the first half and slowly in the second half, it needs to use an additional external throttling switching device to achieve this. [0003] However, adding additional external throttling switching equipment will make the hydraulic and mechanical systems of the lifting mechanism more complex and require a larger space. Contents of the invention [0004] In view o...

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Problems solved by technology

[0003] However, adding additional external throttling switching equipment will make the hydraulic system and mechanical system of the lifting mechanism more complicated, and at the same time need to occupy a larger space

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