| 摘要 |
An articulated boom crane, constructed to allow convenient conversion to straight boom crane operation, and having a secondary boom that has adjustably extensible members supporting a boom tip assembly and that can be selectively coupled to a main boom either in an articulated crane configuration or in a straight boom crane configuration. In the disclosed embodiments, this selective coupling is effected by means of sets of attachment plates fixed to the secondary boom which allow either end portion of the boom to be attached to a pair of side plates pivotally connected to the main boom. Centering posts on the secondary boom aid in aligning the side plates and attachment plates, and tapered pins are engaged through holes in the plates, to provide their secure coupling. When the crane is in the straight boom configuration, stop plates on the side plate prevent movement of the secondary boom with respect to the main boom as a result of load forces. In an alternative embodiment of the invention, conversion to straight boom operation is achieved by use of an extensible member that can be extended from either end of the secondary boom, and a boom tip assembly that can be selectively attached to the projecting end of the extensible member. |
