| 摘要 |
The present invention relates to a derrick crane having a transverse outrigger at the top of the crane post and a derrick boom 7, the top end of which is connected to the opposite ends of the outrigger by means of two boom- topping tackles 16s, 16p via a universal joint coupling 45, 46, 48 and swivel, the invention being characterized in that the derrick crane can operate with the boom 7 in a variety of angular positions within a relatively large angle sector, for example 300 degrees, without the boom- topping tackles seizing up and being rotated one about the other as a result of those ends of the boom-topping tackles 16p, 16s situated closest to the boom top each being connected to a respective swivel 64, 64p and 64, 64s, which swivels, in turn, are connected to the universal joint coupling and hence to the boom top via a common swivel (for example 47, 50), about whose rotational axis the two first-named swivels are together rotatable, whereby a pivotal or rotary motion of one topping tackle produces a corresponding evasive action of the other boom topping tackle as a result of two tackles being rotated as a unit about the rotational axis of the third tackle. <IMAGE> |
