| 摘要 |
<p>An earth boring drill employing roller cutters is provided with a seal in a peripheral groove to inhibit ingress of detritus into the cutter bearing area and engress of lubricant therefrom. The shape of the seal is such that its cross section is not overly compressed or displaced when in operating position, thus preventing undue compression set, wear and heating of the seal. A preferred seal has a greater radial dimension than axial dimension by a ratio of at least one-and-one-half to one to conserve bearing space and to provide the necessary flexibility to accommodate the various movements of the cutter relative to the shaft upon which it is rotatably mounted. The roller cutter has a counterbore fitting over a short cylindrical boss from which the shaft extends on which the cutter is mounted. This provides a tortuous passage restricting ingress of detritus and substantially improved life of the drill bit.</p> |
