| 摘要 |
PROBLEM TO BE SOLVED: To prevent a footstool from coming off a top plate even when the footstool is not perfectly attached to the top plate. SOLUTION: The top plate 15 includes: footstool attachment holes 15a arranged at an attachment position for attaching the footstool 20; and a footstool restraining block 15b projectingly arranged at one end to be on the lower side when the top plate 15 is raised. The footstool 20 includes: a positioning pin 23b which is energized toward the top plate 15, is engaged with the hole 15a, and positions the footstool 20 at the attachment position; and regulation means (stoppers 24, and an opening/closing regulation pin 23c) for performing a first regulation for regulating the movement of the positioning pin 23b so as not to be separated from the top plate 15 from the projection end of the block 15b when the positioning pin 23b proceeds into more on the side of the top plate 15 from the projection end of the block 15b, and besides, performs a second regulation for regulating the movement of the positioning pin 23b so as to keep the engagement state with the engaged hole 15a when the positioning pin 23b is engaged with the hole 15a. COPYRIGHT: (C)2010,JPO&INPIT
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