<p>Fluid flow control valves are provided having a jet pump or aspirator (53) connected to a plurality of fluid passageways. Fluid flow from one of the passageways through the jet pump (53) creates a partial vacuum enabling fluid flow to be drawn through the other of the fluid passageways connected to the jet pump (53). Such valves enable hydraulic fluids of a single-acting piston-cylinder unit or the like to be readily exhausted. In a provided system of this invention, hydraulic or pneumatic pumps may be employed for cylinder exhaustion.</p>
