| 摘要 |
785,231. Ladders. BENSON, E. May 22, 1956 [Feb. 22, 1955], No. 5207/55. Class 20(2) A telescopically extensible loft ladder comprises an upper section 8 slidably mounted within a lower section 9 and on the upper surface of the trap door 1 so that when the ladder sections are collapsed and slid into the loft the overbalancing weight of the ladder will close the trap door. |
