(under subclass 394) Apparatus in which the deformable member comprises a relatively thin membrane like element having a peripheral edge portion, said member being adapted to be associated with a surrounding or encompassing tubular rigid chamber forming means and extending transversely thereof to form a separating wall for dividing said chamber into respective motor and pump chambers, the outer peripheral edge of said membrane being in sealing relationship with the encompassing wall of said tubular structure.
(1) Note. The membrane like member need not span the entire space within the encompassing wall of the tubular member, but may be in the form of a ring or frustum having the inner peripheral edge thereon in sealing engagement with a rigid element movable relative to and coaxial with the encompassing tubular member.
