Rock bit with bearing lubricant reservoir

Claim 1

A rotary rock bit comprising: a bit body defining a pressurized fluid flow path therethrough and having at least one arm terminating at its free end in an axle portion; a rotatable cutter member having an internal open cavity for receipt therein of said axle portion in radial spaced relation to define an annular bearing cavity; annular bearing and cage assembly means disposed in said annular cavity and comprising: at least one annular array of rolling load bearing elements, with all bearing elements thereof retained in said annular array by being caged in and in intimate contact with a permeable porous plastic material having a flowable lubricant in the pores thereof and providing a lubricating cage for said rolling bearing elements, said at least one annular array of rolling bearing elements and plastic material substantially filling the annular bearing cavity adjacent the initial portion of said open cutter cavity; and a lubricant reservoir in said body and lubricant passages therefrom to said bearing cavity terminating adjacent said cage, lubricant in said reservoir and passages and means for pressurizing said lubricant to force lubricant to flow from said reservoir to adjacent said permeable porous plastic material to replenish through capillary draw thereinto the lubricant lost from said pores of said material during use.