(under the class definition) Apparatus comprising a runner* having a plurality of spaced surfaces, the working fluid* passing through the spaces and the surfaces being in the form of sinusoids or comprising alternate ridges and grooves.
(1) Note. In order to qualify under this definition, the working fluid* must travel a tortuous path through or against the runner*. A runner* made of a complementary corrugated or sinuous surfaces which, however, permits the working fluid* to pass therethrough in a path which is not tortuous, corrugated or sinuous is excluded under this definition.
