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Hughes patented O-ring seals prevent drilling fluid from
entering the journal bearing and retain special grease in the
bearing.
Patented pressure relief valves automatically release
excessive pressure build-up inside the bearings, a feature that
protects the O-rings and the compensator system from possible
damage by unbalanced pressure.
Widely spaced long teeth are most effective in soft
formations while closely spaced short teeth are more effective in
hard formations. The chert bit, with tungsten carbide inserts, is the
ultimate in this respect, but the higher cost cannot always be
justified.
A cross-section of a conventional 2-cone bit, illustrates the
relationship of the various elements in cone-type bit design. The 2-
cone type is used to show the relationship of all parts in a single
plane. What will be said about various parts in this design and their
relationships also applies to the 3-cone design.

Figure 6.3 – Hughes tricone bits for soft formations

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