Telescopic box-section crane jib - bearings of smaller sections movable in three dimensions against larger ones

摘要

The jib is also for use with overhead maintenance platforms, each section being supported at one end by a bearing on the end of the larger section enclosing it on the underside, and having at the other end a further bearing running against this larger section. This latter bearing being between the smaller section (2-4) and the underside of the top web of the larger one (1-3) is movable in three dimensions. It can comprise a spindle at right angles to the jib section (5), supported at the centre in the smaller section in a pendulum bearing and with rollers (8) at the outer ends. Stops are provided on either side of the spindle, limiting the distance through which it can slew.