| 摘要 |
PROBLEM TO BE SOLVED: To prevent overwind at the jib angle at which a jib can be reversed by detecting the offset angle of the jib, and automatically stopping the winding operation of a winch when the offset angle reaches a preset value as an angle at which the jib can be reversed. SOLUTION: A limit switch 20 and a weight 21 are fitted to a swing bracket 19, the posture of the swing bracket 19 is changed according to the change in the ground angle of a boom by the effect of the weight 21 so that the position of the limit switch 20 is moved. A striker 23 is fixed to a base end part of a jib 4 in a opposite manner to a contact 20a of the limit switch 20. The positional relationship of the limit switch 20 and the striker 23 is set so as to be functioned only when the offset angleβreaches the set value and the ground angleαreaches the set value at the same time. Thus, when both angles reaches the respective values, the limit switch 20 is operated, and the winding operation of a hook for auxiliary working is stopped.
|
