Portal crane with post-supported loading arm etc.

摘要

A drive wheel (13) in the centre of each base beam (8) below the post is carried on an axis fixed at right angles to the beam and can be raised against a spring (17). Each wheel has its own hydraulic motor (20). Both motors are connected to a crane-fitted unit complete with oil pump and metering device so each wheel can be run separately at selected peripheral speed. Each of the two wheels is carried within a wheel box (14) having a top-fitted guide shaft (15) in pipe form which is non-twistably enclosed in bearing sleeve (16) to permit limited vertical movement against the coiled compression spring. The spring thrust off the base of the shaft and above under pre-tension against the sleeve end cover.