| 摘要 |
The ladder has adjustable anchor hooks mounted towards the top of the longerons. The mounting provides for transverse or vertical displacement of the hooks. The hooks can, thus, be utilised to secure the head of the ladder to fixed objects in a range of alternative positions. The hooks may be mounted on slides which travel along the longerons and lock in the desired position. Locking may be effected by lever-operated cams or by locking-screws, and the hooks may swivel or pivot to give transverse adjustment. A partic, detail may have the hooks mounted on sleeves on axles which cantilever from a ringed runner. The tunner is threaded on the longeron to travel vertically between the two top rungs. |
