Importance

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Abstract

A lower boom is pivotally mounted on a turntable and moved upwardly and downwardly by a hydraulic cylinder, the lower end of which may be pivoted on the same pivot shaft as that on which a pair of links are pivoted. The outer ends of the links are pivotally connected to the lower end of a knee joint, preferably formed of heavy plate and attached to the inner end of an upper boom, while the outer end of the lower boom is pivotally attached to the knee joint above the links. An extensible boom, hydraulically moved inwardly and outwardly of the upper boom, may carry a workman's basket and/or a hydraulic nozzle, as for extinguishing fires. The distance between the pivotal connections of the links and the lower boom to the turntable, the relative length of the lower boom and links and the distance between the pivotal connections of the outer ends of the lower boom and the links to the knee joint or upper boom are preferably proportioned so that the outer end of the extensible boom, at any set position, will rise in a generally vertical line, as the lower boom is elevated. During such movement, the knee joint will remain on the opposite side of the center line of the turntable from the extensible boom and basket, thereby contributing materially to the balance of the structure and thereby, in many installations, avoiding the use of jack legs or outriggers. A special line for supplying water to the nozzle consists of pipes attached to the upper and lower boom, an extensible pipe within the upper boom pipe, hose connections between the pipes and between the lower end of the lower boom pipe and a supply pipe. The latter includes special fittings permitting the turntable to move through 360.degree. or more.

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First Claim