Appeal No. 1999-2131 Page 17
Application No. 08/971,504
(86) is shown as next to roller cutter (60). The examiner
should determine whether Drakes's thrust washer (86), in the
floating mode i.e. with some clearance between the washer and
both the main body (50) and cutter (60), would have inside and
outside diametric clearances as described by the appellants'
specification at page 9, lines 9-16, and, if so, whether the
limitations of the appellants' claims (e.g., claim 49) are
met, or obviated, by Drake.
With respect to group 2), the appellants' claims 44-48
and 59-64, Childers et al. (U.S. Patent No. 4,323,284 cited at
column 2, line 12 of Drake) discloses that materials used in
rolling cutter drill bit thrust bearings have included
stellite alloys, such as stellite 6 (column 2, line 48). The
appellants' own disclosure teaches that the room temperature
yield strength of stellite materials is less than 120,000 psi
(specification, page 5, lines 1-6) and that a ductile stellite
material at room temperature may have a minimum yield strength
of around 80,000 psi and a ductility of at least 4%
(specification, page 7, lines 18-21). The examiner should
consider whether the drill bit set forth in the appellants'
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