| 摘要 |
An extension ladder (1) comprises a plurality of ladder sections (2), connection kits (3) and transverse step beams (5). Each ladder section is a hollow rail having different caliber, which can be interconnected by telescoping with each other. A snap-fit mechanism is provided between the upper ladder section and the lower ladder section to make them not slip when the extension ladder is extended. The upper end of each ladder section is provided with a connection kit transverse provided. The upper end of the connection kit is provided with a fixed protuberant pin (300), an inside thereof is provided with a locking mechanism (4b). The locking mechanism (4b) is provided with a turning key (440) . An outside of the connection kit is covered by the transverse step beam. When the upper connection kit and other lower connection kit are close to each other, the protuberant pin of the lower connection kit pushes the turning key in the connection kit so that the locking mechanism of the upper connection kit can be unlocked to make the upper ladder sections fall automatically in turn. |
