| 摘要 |
The present invention reduces neck injuries when a structure having a lifting mechanism section only on one side is adopted. While a lifting drive section (160) is provided on one side frame (11) side, a coupling drive rod (170) is connected to the rotation center of a drive gear (160d), a driven link (171) is provided on the other side frame (11) side, and the driven link (171) is connected to the coupling drive rod (170). Although the driving force at the lifting drive section (160) acts on the one side frame (11) side where the drive gear (160d) is provided, lifting takes place also at the other side frame (11) side as the driven link (171) rotates in conjunction with the drive gear (160d) via the coupling drive rod (170). Because the virtual quadrangle formed by connecting the respective contact points of the driven link (171), side connectors (153, 153), the coupling drive rod (170), and the drive gear (160d) is never deformed, external input is dispersed. |
