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jib crane[′jib ‚krān]
a hoisting crane of the bridge variety, in which a telpher moves along a drive beam.
The running wheels of the beam rest on rails, which are usually set on the upper racks of subcrane beams, situated under the ceiling of an installation, covered platform, or construction area. In certain structures the running wheels rest on lower racks of subcrane H-beams. Jib cranes of such a design are called suspended or rolling. Jib cranes are single-span (width of a span is 6-15 m) and multispan (up to 100 m). Jib crane mechanisms are activated by electric motors running on a power network (overhead wire or cable). The mechanisms are controlled by an operator in a cabin perched on the drive beam or from the floor of the installation by means of a push-button console connected by cable with the jib crane mechanisms. The lifting capacity of jib cranes is generally 1-5 tons.
Jib cranes (cat davits) on ships are very basic hoisting and sluing cranes for the lifting and lowering of main (bow) anchors. They are shaped in the form of a curved beam with a pulley at the end or jibs with struts. The anchor is lifted manually or by means of a windlass. One jib crane is positioned on the forecastle and two along the sides of the forecastle. On wooden sailing ships the role of the jib crane is assumed by two stationary wooden outriggers (beams on the bilges of the forecastle), referred to as catheads.
E. I. RIDEL’