Mobile crane having counterweight

Abstract

Provided is a mobile crane capable of adjusting a counterweight height with no use of a costly hydraulic cylinder. The mobile crane comprises a lower propelling body, a upper slewing body, a boom pivotably attached to the upper slewing body, a mast which is at the rear of the boom and adapted to be raised and lowered so as to raise and lower the boom, a counterweight which is at the rear of the upper slewing body and hung from the mast through a guy line, and a counterweight-lifting cylinder attached to the counterweight so as to be extended to vertically push up the counterweight with respect to a ground surface. The counterweight-lifting cylinder has a cylinder body, a piston partitioning an internal space of the cylinder body into an upper head-side cylinder chamber and a lower rod-side cylinder chamber, and a rod extending from the piston downwardly beyond an lower end of the cylinder body. the counterweight-lifting cylinder is extended by supply of a hydraulic pressure into the head-side cylinder chamber and retracted by supply of a hydraulic pressure into the rod-side cylinder chamber.

Description

technical field [0001] The invention relates to a mobile crane, in particular to a mobile crane with a counterweight. Background technique [0002] Conventionally, there is known a large mobile crane including a counterweight for increasing the hoisting capacity. For example, Japanese Patent Laid-Open Publication No. 2008-297112 describes a mobile crane comprising: a base carrier; a slewing upper structure slewing on the lower carrier; A mast with a lattice structure on the upper revolving body; and a counterweight suspended from the upper end of the mast to the rear of the upper revolving body by a guy line. This type of mobile crane, by changing the horizontal distance from the support point of the base end of the mast (hereinafter referred to as the mast foot, mast foot) to the center of gravity of the counterweight (hereinafter referred to as the "suspension radius of the counterweight") or the distance of the counterweight Quality, to adjust the lifting capacity of th...

AI Technical Summary

Problems solved by technology

[0009] However, in the technique, since the balance weight 50 is pulled up using the contraction of the fluid pressure cylinder 160 or the fluid pressure cylinder 260, the driving efficiency of the fluid pressure cylinder 160, 260 is poor.

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