Appeal No. 1999-2131 Page 2
Application No. 08/971,504
THE INVENTION
The appellants' invention relates to a thrust bearing in
rolling cutter drill bits (specification, p. 1). A copy of
the claims under appeal is set forth in the appendix to the
appellants' brief. Claims 1, 44 and 49 are representative and
read as follows:
1. A rolling cutter drill bit comprising a body and a
plurality of legs, at least one of said legs having a
cantilevered bearing spindle, a rolling cutter rotatably
mounted on the bearing spindle, lubricant delivering means
within the bearing spindle, and a floating thrust bearing
element configured to carry onward thrust loads from the
rolling cutter onto said bearing spindle, said floating thrust
bearing element being formed of a wrought alloy material
consisting primarily of chromium carbide and cobalt and having
a yield strength of less than 120,000 psi and a ductility of
at least 4%, both at room temperature.
44. A drill bit comprising:
a body having a leg, the leg having a cantilevered bearing
spindle;
a cutter rotatably mounted on the bearing spindle; and
a bearing element configured to carry loads between the
rolling cutter and the bearing spindle, the bearing element
formed of a material comprising a cobalt-based superalloy
having a yield strength of less than 120,000 psi and a
ductility of at least 4% at room temperature.
49. A drill bit comprising:
a body having a leg, the leg having a cantilevered bearing
spindle;
a cutter being rotatably disposed on the bearing spindle; and
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