(under the class definition) Apparatus wherein a working member* comprises a fluid reaction surface having a part or a member mounted thereon for varying the flow of fluid to or from the working member and including positive means to move the flow varying member relative to the fluid reactive surface while the working member is being operated in its intended manner.
(1) Note. A working member comprised of relatively movable parts movable merely for the purpose of increasing or decreasing the effective operative diameter or the apparatus is not included in this definition and is classified in subclass 88 below.
