Patent ID: 8057125

Claim:
A method of making a vibratory percussion rammer, the method comprising: providing a motor-driven gearbox and a percussion unit extending downwardly from the gearbox, the percussion unit comprising a ram and shaft assembly extending downwardly from the gearbox into a guide cylinder, a spring box extending upwardly into the guide cylinder, and a spring separator coupled to the ram and shaft assembly and disposed in the spring box between upper and lower springs, the ram and shaft assembly configured to reciprocate up and down and the spring box configured to reciprocate divergently relative to the reciprocations of the ram and shaft assembly; forming a plurality of slide bearings out of a plurality of sheets of non-metal material having a length and a width by shaping each sheet in the plurality of sheets into a tube having a C-shape in cross-section that defines an open seam having a width and extending along the entire length of the slide bearing; inserting a first slide bearing from the plurality of slide bearings between the guide cylinder and the ram and shaft assembly and spring box, wherein the first slide bearing has an open seam that is wider than an anticipated width-wise thermal expansion of the first slide bearing during normal operation of the vibratory percussion rammer so as to prevent contact between the guide cylinder and the ram and shaft assembly and spring box; inserting a second slide bearing from the plurality of slide bearings between the spring separator and spring box, wherein the second slide bearing has an open seam that is wider than an anticipated width-wise thermal expansion of the second slide bearing during normal operation of the vibratory percussion rammer so as to prevent contact between the spring separator and spring box; inserting a third slide bearing from the plurality of slide bearings between an upper portion of the spring box and a shaft of the ram and shaft assembly, wherein the third slide bearing has an open seam that is wider than an anticipated width-wise thermal expansion of the third slide bearing during normal operation of the vibratory percussion rammer so as to prevent contact between the upper portion of the spring box and the shaft of the ram and shaft assembly; and selecting the material of said first slide bearing such that said first slide bearing will fail under extreme operating conditions prior to failure of either of the second or third slide bearings.