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A cylinder retraction system causes a crawler side frame hoisting hydraulic cylinder, swingably suspended on a ventral surface side of a lower boom, to swing between a retracted attitude, in which the hydraulic cylinder is set along a ventral surface of the lower boom, and an operating attitude, in

A cylinder retraction system causes a crawler side frame hoisting hydraulic cylinder, swingably suspended on a ventral surface side of a lower boom, to swing between a retracted attitude, in which the hydraulic cylinder is set along a ventral surface of the lower boom, and an operating attitude, in which the hydraulic cylinder is oriented along a vertical direction. As the rod of the hydraulic cylinder, currently having the operating attitude, is contracted by a predetermined extent, the rod front end of the hydraulic cylinder is guided by the guiding portion until the hydraulic cylinder takes on the retracted attitude. As the hydraulic cylinder, currently having the retracted attitude, is extended by a predetermined extent, engagement between the rod front end of the hydraulic cylinder and the guiding portion is released so as to allow the hydraulic cylinder to take on the operating attitude.

대표청구항 ▼

1. A crawler crane comprising a traveling lower superstructure, a revolving upper superstructure rotatably disposed upon the traveling lower superstructure and a boom of which base end portion is pivotably attached to the revolving upper superstructure, the traveling lower superstructure having a ca

1. A crawler crane comprising a traveling lower superstructure, a revolving upper superstructure rotatably disposed upon the traveling lower superstructure and a boom of which base end portion is pivotably attached to the revolving upper superstructure, the traveling lower superstructure having a car body linked to the revolving upper superstructure, a pair of crawlers detachably mounted on both sides of the car body, each of the pair of crawlers configured so as to include a crawler side frame and a crawler belt wrapped around the crawler side frame, wherein the crawler side frame is detachable to and from the car body for the crawler crane itself, comprising: a hydraulic cylinder swingably suspended on a ventral surface side of the boom, and having a rod extended and contracted by hydraulic oil, and equipped with a mounting fixture attached at a front end of the rod for suspending the crawler side frame;a cylinder retraction system including a pair of guide plates set apart from each other over a predetermined distance on two opposite sides of the rod, each of which base end side rotatably supported on the ventral surface side of the boom, and configured so that front edges of the pair of guide plates being rotated between a retraction portion closer to the ventral surface side of the boom and an operating position over a greater distance from the ventral surface side of the boom; whereina through hole is formed at the mounting fixture, a round bar shaped guide pin or a shackle for suspending the crawler side frame is selectively attached to the through hole;when the hydraulic cylinder has been disposed in vertical direction in a condition in which the round bar shaped guide pin has been inserted through the through hole to assume an operating attitude, and the hydraulic cylinder has been made to contract in a condition in which the pair of the guide plates have been set in the operating positions, then the round bar shaped guide pin is guided via the pair of guide plates, and the hydraulic cylinder assumes the retracted attitude in which the hydraulic cylinder are disposed along the ventral surface side of the boom;when the hydraulic cylinder has assumed the retracted attitude in a condition in which the round bar shaped guide pin has been inserted through the through hole, and the hydraulic cylinder has been made to extend in the condition in which the pair of the guide plates have been set in the operating positions, then the round bar shaped guide pin is guided via the pair of guide plates, and the hydraulic cylinder assumes the operating attitude; andwhen the hydraulic cylinder has assumed the operating attitude, and the round bar shaped guide pin or the shackle has been attached to the mounting fixture, the crawler side frame is made suspensible. 2. The crawler crane according to claim 1, wherein a pair of retainer plates is disposed at the ventral surface side of the boom;a lock pin engaging with the pair of retainer plates is disposed at the hydraulic cylinder;when the lock pin has engaged with the pair of retainer plates, the hydraulic cylinder is kept assuming the retracted attitude; anda pin holding hole for temporarily holding the lock pin at the pair of retainer plates is formed through each of the pair of retainer plates.