Abstract: A heavy duty lubricating composition for lubricating metal rubbing surfaces, such as journal bearings in rock bits, is provided that forms a solid as a result of increased temperature at the areas of highest shear rate or highest loading in the bearing. The solid reverts to its original state within the carrier fluid when passing into areas of lower temperature. The composition comprises a substantially uniform dispersion within a carrier fluid of a solid additive having decreasing solubility/dispersibility in the carrier fluid as temperature increases, an additive capable of forming with the carrier fluid viscous lubricating solutions in water, and an extreme pressure agent having a high temperature of activation with the bearing materials.

Abstract: A rotary drill bit for drilling earth formations is disclosed having a plurality of cutting elements mounted on the head portion of the bit. The bit further includes a plurality of individual protrusions projecting from the head portion more than the extension of the cutting elements. The protrusions are fabricated of a metal more readily abraded by the earth formation than any of the cutting elements. The protrusions protect the cutting elements during handling of the bit and entry of the bit into a borehole; and, the protectors are abraded away to expose the cutting elements during drilling.