Highly maneuverable insulated man lifting aerial crane for use in servicing overhead high-voltage electrical transmission lines.

摘要

A powerful, highly maneuverable, man-lifting crane has three vertically articulating sections (26,28,30) which swivel on a common turret (22) for horizontal positioning, the third or outer section (30) of the group comprising three telescoping, tubular booms (60,62,64) wherein the outermost boom (64) is constructed of a dielectric material such as fiberglass for carry­ing an electrically insulated man-lifting bucket (188) at its outer end. A pair of hydraulic extension and retraction cylinders for the telescoping booms of the third section are both housed internally of the section and are mechanically interconnected and hydraulically coupled in such a way that, upon extension of the third section, the fiberglass boom always extends first and, upon retraction of the third section, the fiberglass boom always retracts last. One of the booms of the third section utilizes an unusually long rod in connec­tion with its hydraulic cylinder unit, which rod is supported against bending and twisting by a unique, sliding support coupled in a lost motion connection with the fiberglass boom. A radio transmitter (186) carried in the lifting bucket enables the workman to control all operating functions of the crane from the bucket itself without creating an electrically conductive path to ground poten­tial through control wires and cables.