| 摘要 |
PURPOSE:To enhance the safety for a worker at a high level, by enabling a working bed to be lowered by manipulation of the worker when any abnormality occurs in a hydraulic circuit for an elevator device ina high level working vehicle. CONSTITUTION:When a control member provided in an operating mechanism is manipulated in the case of that an abnormality occurs in a hydraulic circuit in such a condition that a working bed 4 is positioned at a high level, and therefore the working bed 4 may not be lowered, solenoids 18a, 20a, 22a are energized to open control valves 18, 20, 22. Then, oil in a cylinder bottom chamber 6a is fed into a cylinder rod chamber 5b, and oil in tank T is discharged so that cylinders 5, 6 retract to lower the working bed 4. At this time vacuum is effected in a cylinder rod chamber 6b, but a part of oil in a bottom chamber 5a is fed into the chamber 6b so that the elevating cylinder 6 smoothly retracts. Thus, the working bed 4 is safely lowered by manipulation of the worker at a high level. |
