(under subclass 437) Apparatus in which the means to control the flow of fluid into or out of the chamber comprises a distributor, said distributor being at least partially moved cyclically by a fluid reactive surface formed on the distributor, or formed on an element adapted to contact the distributor means.
(1) Note. The reactive surface excludes the areas of the distributor means which are subjected to pump pressures as the working fluid is moved to and from the working chamber.
