| 摘要 |
<p>The ladder is suitable for use in ascending telegraph poles, lamp posts, and other mast or pylon structures. A hydraulic tongs unit (5), with hydraulic mechanism (8-10) activated from the bottom end of the stringers (2), is fastened to a rotatable shaft (3), between the stringer top ends (1). Its jaws (6, 7) open and close parallel to the line of the rungs and the shaft axis. A safety device can be provided, to prevent unintentional release of hydraulic pressure when the tongs are clamped. The shaft rotation may be limited by a stop which is arranged to keep the mast in a plane, parallel to the ladder plane. A second stop may permit an angular motion of pref. 45% in relation to the first stop.</p> |
