The invention provides a boom extending and retracting apparatus of a crane. Multiple boom members (21) are made to slide by a shared telescopic cylinder (12) through the motion of a normal fluid circuit or a differential fluid circuit of a fluid circuit (14). After the operating lever (95) is turned to an extension side and the extension of a telescopic boom (13) starts by using the differential fliud circuit, and when the operating lever (95) is again operated to the extension side, a control unit (93) choose the normal fluid circuit. Through the re-operation of the operating lever (95), the motion of using the differential fluid circuit is switched to the motion of using the normal fluid circuit, the telescopic boom (13) extends. Thus, in a crane, the boom extending and retracting apparatus reduces the burden on the operator and improves the use convenience of the telescopic boom.
Boom extending and retracting apparatus of a crane
2015-06-03
Patent
Elektronische Ressource
Englisch
IPC: | B66C Krane , CRANES |