| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an operation control device of a boom telescopic mechanism for further surely fixing and connecting mutual booms and mutual cylinder booms, by reducing cost by restraining the number of part items. <P>SOLUTION: In this operation control device 30 of the boom telescopic mechanism, a single-acting type second hydraulic cylinder 43 for advancing-retreating inter-boom fixing pins 41 and 41' for fixing and releasing a fixation of the mutual booms of a telescopic boom of constituting a plurality of booms in a nesting type, communicates with a directional control valve 61 for supplying and discharging a hydraulic fluid delivered from a hydraulic pump P via a first oil passage 63. A single-acting type first hydraulic cylinder 34 for advancing-retreating a cylinder boom connecting pin 32 capable of connecting and releasing the connection of the mutual booms adjacent to a telescopic cylinder 20 for expanding the telescopic boom, communicates with the directional control valve 61 via a second oil passage 64. The directional control valve 61 releases a fixation by a pin corresponding to a supply side hydraulic cylinder when supplying the hydraulic fluid to one of the first or second hydraulic cylinder 34 or 43, and performs the fixation by energizing the pin corresponding to an unsupplied side hydraulic cylinder by an energizing spring. <P>COPYRIGHT: (C)2010,JPO&INPIT |
