| 摘要 |
<p>Lifting apparatus including a device for limiting the range of the apparatus comprises at least one telescopic boom 6 mounted via a pivot 5, having a horizontal axis, on in the end of an articulated boom 4 which is itself mounted on a rotating turret 2, the boom 6 comprising a first unit which is axially stationary, and one, two, three or more telescopic units. A movable rod 12 is associated with the boom 6 in order to detect lengthening and shortening movements of the same. Flexible transmission means 17% connects the rod 12 with a pulley mounted coaxial with the pivot 5. An electrical switch 19 is mounted on one end of the flexible transmission 17%, which passes over said pulley. The switch 19 is normally in the closed position and is incorporated into a circuit controlling the extension of the boom 6. A plate 20 is secured in order to remain stationary and has a check profile which reproduces the trace of the maximum permissible range for the various conditions in which the apparatus is used. The switch 19 at all times faces the plate 20 and becomes activated in order to break the boom extension circuit when it reaches or passes beyond the check profile of the plate 20. <IMAGE></p> |
