Abstract: A jib crane system comprising a horizontally extending load beam rigidly attached to the upper end of a vertically extending mast. The lower part of the mast is positioned inside a hollow structure such as a pipe and is rotatably associated therein, and spaced from the inside surface of the pipe. A bearing boot is rigidly secured to the mast and in frictional contact with the inside surface of the pipe. The bearing boot slides around the inside circumference of the pipe in a circular or arcuate path as the mast and load beam revolve around the central axis of the mast. The bearing boot includes an outer arcuate concave contacting plate having substantially the same radius as the inside convex surface of the pipe. A ring of foil may be secured on the inside of the pipe for providing the sliding surface for the bearing boot. The mast may comprise a flanged beam having a pair of side walls with a web portion therebetween.

Abstract: A jib crane system comprising a horizontally extending load beam rigidly attached to the upper end of a vertically extending mast. The lower of the mast extends inside a hollow pipe and is rotatably associated with a base plate assembly or rotatably secured in the foundation at the site of the crane. Roller bearings are rigidly secured to the mast and positioned in frictional contact with the pipe. The roller bearing revolves around the circumference of the pipe as the mast and load beam rotate around the central axis of the mast. The roller bearings are adjustable for varying the frictional contact of the rollers with the pipe.