| 摘要 |
A telescopable crab jib for tower slewing cranes comprises a jib base member (40) and a jib head member (41) each of box shaped cross-section and each having a track (21, 22) for a traversible crab, wherein the jib base member and the jib head member, to the extent to which they form the appropriate portion of the crab track, each comprise an identical pair of angle sections (33 or 38), both pairs of angle sections (33 or 38) forming a common continuous crab track (200) in flush alignment when the jib is extended as shown in Figure 6, a box section being arranged above each pair of angle sections (33 or 38), and wherein in order to obtain the retracted state of the crab jib as shown in cross-section in Figure 5 the angle section pair (38) of the jib head member and associated box section (34 to 37) of smaller size are retractable into the jib base member having an angle section pair (33) and associated box section (26) of larger size. <IMAGE> |
