Vibratory percussion rammers and methods of making vibratory percussion rammers

摘要

A vibratory percussion rammer includes a gear box, a percussion delivery unit extending downwardly from the gear box, and one or more slide bearings disposed in the percussion delivery unit between adjacent surfaces of reciprocating metal components. The slide bearings are made from a sheet of plastic material that is curved into the shape of a tube having a C-shape in cross section and define an open seam extending the entire length of the slide bearing. Slide bearings according to this design can be disposed in the percussion delivery unit to eliminate some or all of the metal-on-metal contact between reciprocating components, including between the ram and shaft assembly and spring box and the guide cylinder, the spring separator and the spring box, and the shaft of a ram and shaft assembly and an upper end of the spring box. The seam width of any slide bearing is wider than the anticipated width-wise thermal expansion of the slide bearing during normal operation. When a plurality of slide bearings are used, the slide bearing that is the easiest to replace has a seam selected to close and fail at a temperature in excess of normal operating temperature that is lower than the excess temperature leading to failure of other slide bearings.