| 摘要 |
A boom assembly for mounting on the roof of the building provides a pulley which receives a cable for depending over a front edge of the building to allow lifting or lowering of materials attached to the cable. The boom assembly can be folded to a relatively small packaged arrangement for ready transportation. The boom assembly can be adjusted to accommodate different orientations of support surface for example inclined or angled roof structures. The boom arrangement includes a vertical post, a counterbalance pole extending rearwardly from the base of the post and a pair of arms extending at right angles to the counterbalance pole. A brace is connected between the top of the post and the counterbalance pole with the base extending outwardly and carrying the pulley at the outer end. A cable arrangement extends between the pulley and a rear end of the counterbalance pole. The angle of the post relative to the counterbalance pole can be adjusted in two directions and also the arms can be raised and lowered as required. |
