Patent ID: 8136634

Claim:
A piston arrangement for metering valves, flow-rate sensors, or hydraulic motors, said piston arrangement comprising: a housing; at least one recess in the housing; a first piston sealed and movable in the at least one recess of the housing; a recess in the first piston; a flow passage through the first piston; a second piston movable in the recess of the first piston; a sealing surface on the second piston; and a valve seat on the first piston against which the sealing surface on the second piston is selectively pressed in such a way that the second piston is movable relative to the first piston between a position which opens said flow passage through the first piston and a position which shuts off said flow passage through the first piston; the housing forming an injector body which is adapted to be connected to a manifold, said injector body having a first opening for connecting a first chamber to a supply line in the manifold and an outlet opening which is adapted to be closed by a relief valve and which is connected, in turn, to a connection provided in the manifold.