Tower crane with side folding jib - has rope passing from jib head to inner tower half over pulleys

摘要

The jib folds about an axis parallel to one of the faces of the telescopic tower, under the action of a constant length rope received from the jib head round at the jib foot, a pulley whose spindle is flexible to the top of the inner half of the tower, pulleys forming a block and tackle mechanim between the other halves, and to an anchorage on the lower part of the inner half. One of the pulleys in the black and tackle mechanism (21, 22) is mounted on a truck (23) with a counterweight, travelling up and down in a track.