| 摘要 |
A lifter is provided with operating levers, which, against driving forces of actuators that switch the ratchet pawls to unengaged orientations, switch the ratchet pawls to engaged orientations of being engaged with ratchet gears, is provided with a link mechanism, which, when a workpiece support base is being lowered by collapsing motions of a pair of right and left crosslink mechanisms supporting the workpiece support base and a difference arises in movement amounts of movable support shafts at lower end sides of the respective crosslink mechanisms, converts the movement amount difference to an operating force of the operating lever at the larger movement amount side, and is such that by the operating lever at one side being driven by the link mechanism, the operating lever switches the ratchet pawl at the larger movement amount side to the engaged orientation. |
| 主权项 |
1. In a lifter comprising a workpiece support base, vertically movably supported on a base via a pair of parallel crosslink mechanisms, elevation/lowering drive chains, juxtaposed to the respective crosslink mechanisms and elevatingly and loweringly driving the workpiece support base, and fall prevention means, juxtaposed to the respective crosslink mechanisms, with the respective fall prevention means including ratchet gears, fixed to movement path flanks of movable support shafts, capable of horizontal movement, at base sides of the respective crosslink mechanisms, ratchet pawls, moving horizontally in interlock with the respective movable support shafts and being engaged with the ratchet gears by urging forces to deter lowering of the workpiece support base, and actuators, which, when the workpiece support base is lowered, switch and hold the respective ratchet pawls against the urging forces to and in unengaged orientations of being separated from the ratchet gears,
a lowering process forcible fall prevention mechanism is provided, the lowering process forcible fall prevention mechanism includes a pair of operating levers and a link mechanism, the pair of operating levers switch the respective ratchet pawls in the unengaged orientations to engaged orientations of being engaged with the ratchet gears against driving forces of the actuators, the link mechanism is such that, when a difference arises in movement amounts of the respective movable support shafts during lowering of the workpiece support base, it converts the movement amount difference to an operating force of the operating lever at a larger movement amount side, and by the operating lever at one side being driven by the link mechanism, the operating lever switches the ratchet pawl at the larger movement amount side to the engaged orientation. |
