| 摘要 |
492,303. Loft -ladders. LOFT LADDERS, Ltd., and GORHAM, P. H. March 18, 1937, No. 8013. Addition to 392,940. [Class 20 (ii)] A modification of the loft-ladder described in the parent Specification consists of mounting the counterbalancing spring 3 on a rod 2 attached to the ladder, the lower end of the spring bearing on a runner or slider 4 which embraces the rod and is pivotally mounted on the trap-door 8. As the ladder is raised the slider moves along the ladder and the strain on the spring is lessened. Two springs may be arranged one on each side, or a single spring, centrally of the trap-door. The ladder is carried by a radius rod 9 at its upper end and is provided with a sliding or hinged extension 11. A stop 12 is fixed to the ladder to limit its clownward movement. |
