| 摘要 |
A ladder includes a leveler engages a bottom of each side rail for 1) causing extendable legs to move to a level ground-engaging position, 2) causing the legs to lock when both legs engage the ground, and 3) causing the extendable legs to move to a centered/retracted position when lifted from the ground. The leveler includes pawls, links, pinions, and a shaft forming a four-bar linkage for selectively moving the pawls inward to the disengaged position when the pinion and shaft are each freely rotatable, but selectively moving the pawl outward into locking engagement when the shaft resists movement due to ground engagement by both legs. The leveler can be constructed to attach to an inside of the side rails, thus facilitating pre-assembly. |
