Appeal No. 2001-2140
Application No. 09/217,484
through one piston, or the related limitations in the claim
requiring the threaded portion of the stem to be engaged in a
threaded seat formed in a recess of a head.
Nordlund discloses a valve actuator 1 generally similar
to that disclosed by Messina. In the Nordlund actuator, one
of the conventional end-walls or heads is replaced by the end-
wall 3 of an auxiliary actuator 19 having a cylinder 20, a
piston 21 and a piston rod 22 which can be extended through a
bore 3a in the end-wall 3 to limit the outward stroke of the
actuator’s main pistons. As shown in Nordlund’s drawing
figures, the auxiliary piston rod 22 is unthreaded and tightly
passes through the end-wall 3 via a gasket.
In proposing to combine Messina and Nordlund, the
examiner concludes that it would have been obvious to one of
ordinary skill in the art
to make a part of Messina’s stem 36 unthreaded, that
part which moves along piston 35, and to add a
gasket to that area of piston 35, both features
shown by Nordlund, to prevent fluid leakage . . . as
it is well known in the fluid handling art to make
connections which prevent leakage. Additional
motivation would be to minimize wear to the
[Messina] piston 5 and 35 and the stem 36 as threads
would cause significant wear to both pieces [answer,
pages 3 and 4].
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