| 摘要 |
PROBLEM TO BE SOLVED: To alarm a cause of stopping the control to a worker for rapid countermeasures by providing a working limit detecting means to detect the mechanical work limit of a hydraulic cylinder, and a sound alarming means to alarm by voice that the hydraulic cylinder reaches the mechanical work limit. SOLUTION: The boom derricking angleθand the boom length L of an expandable boom 5 are incorporated from a derricking angle detecting means 11 and a boom length detecting means 12, and the elevation limit reference valueθmax and the collapse limit reference valueθmin corresponding to the pre- stored mechanical work limit of the derricking boom 3, and the maximum expansion limit reference value and the minimum contraction limit reference value corresponding to the mechanical work limit of an expandable cylinder 4 are red one after another. Whenθ=θmax , andθ=θmin , an alarm that 'The derricking cylinder reaches the stroke end, and the control is stopped.' is given by the voice by a voice alarming means 15. When L=Lmax and L=Lmin , an alarm, for example, that 'The expandable cylinder reaches the stroke end, and the control is stopped.' is given.
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