| 摘要 |
PROBLEM TO BE SOLVED: To prevent the collision of a boarding and alighting door with a step board, because the step board in a storage position can be returned to a working position, when an operator gets off an operator cab. SOLUTION: A hydraulic cylinder 208 is held in a state (storage position) along the outside of the door 112 by driving the step board 206 upward. The hydraulic cylinder 208 is expanded/contracted by a step switch 303 and an unlocking switch 204, which are provided in the operator cab 110. For example, in the case where the step switch 303 is operated so that a controller 305 can switch an electromagnetic switching valve 302 and where a bottom chamber of the hydraulic cylinder 208 communicates with a tank, the hydraulic cylinder 208 is contracted so that the step board 206 can overhang by turning to the working position from the storage position. COPYRIGHT: (C)2011,JPO&INPIT
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