| 摘要 |
IMPROVED ROCK BIT of the Invention A rotary cutting member of a rock bit is journaled on an axle portion of the bit body and provides a cavity between the axle portion and cutting member in which there are disposed a plurality of bearing elements for rotatably supporting the loads of the cutting member on the axle portion. A pressurized fluid passageway extends through the bit body to the cavity for transmitting bearing conditioning fluid to the bearings. At least one annular array of bearing elements is encased and supported in a ring of semi rigid porous, permeable plastic material having bearing lubricant in the pores and forming the bearing cage. The cage and encased bearing elements fill the radial distance of the cavity to initially substantially block delivery of bearing conditioning fluid through the cavity. Under bit operating conditions the plastic material is generally expelled from the cavity thereby opening the cavity to the pressurized bearing conditioning fluid from said fluid passageway, |
