| 摘要 |
A boarding ladder assembly for mounting a boarding ladder on a support for movement between raised storage and lowered boarding positions. The assembly includes a guide structure that has first and second guide tracks mounted in spaced diverging angular orientation relative to each other and first and second guide track followers that are mounted therein for changing the angular orientation of the boarding ladder as it is raised and lowered. A counterweight has an actual weight greater than the weight of the ladder. A linkage is connected between the counterweight and ladder at a lift angle that varies as the ladder is raised and lowered to cause the counterweight to exert an actual lifting force that is sufficient to overcome the ladder weight when the ladder is in a raised position and that is less than the weight of the ladder when the ladder is in its lowered boarding position to automatically maintain the ladder in either position without the need for a latching mechanism. |
