(under subclass 44.2) Apparatus wherein the motor comprises an electrical circuit and the sensing means includes a relatively thin membranelike member having a peripheral edge portion, said member being adapted to be associated with a surrounding or encompassing tubular rigid structure to extend transversely thereof to form a closing wall for said tubular structure, the outer peripheral edge of said membrane being in sealing relationship with the encompassing wall of said tubular structure; said member moves in response to the fluid pressure variation causing the electrical circuit of the motor to close or open.
(1) Note. The membranelike 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 thereof in sealing engagement with a rigid element movable relative to and coaxial with the encompassing tubular member.
