| 摘要 |
<p>The safety mechanism consists of two arms (8) pivoted to the upper ends of the ladder side supports (2a,b) which are opened to allow them to pass round the sides of a pole (1) and closed round the back of the pole by a cord (14) which also acts as a safety line for a person using the ladder. In their non-operative position the arms are folded against the front of the ladder and are turned into the closed position by two levers (16) which connect the arms to the cords, while the latter has two looped ends (15a,b) passing through lugs (18) on a cross-piece (19) equipped with rollers (12) which press against the front of the pole when the ladder is in use.</p> |
