| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a boom extension device for a mobile crane provided with a structure surely preventing a boom from sliding down accidentally by linking a releasing action of an inter-boom connecting/disconnecting means used for fixing/releasing booms mutually and a connecting action of a cylinder- boom connecting means so that they work directly on a fixing pin in the inter- boom connecting/disconnecting means and a connecting pin in the cylinder-boom connecting means for surely restricting a relative action between both means. SOLUTION: In release of connection by means of the cylinder-boom connecting means 8, a connecting action controlling member 13 is positioned in a traveling path for fixing action controlling members 10, 11, so that a movement of the fixing action controlling members 10, 11 is restricted and release of the fixed fixing pin 9A is restricted. In release of the fixed fixing pin 9A, the fixing action controlling members 10, 11 are directly positioned in a traveling path for the connecting action controlling member 13, so that the connecting action controlling member 13 is restricted from moving and a connection releasing action by the cylinder-boom connecting means 8 is restricted.</p> |
