Patent ID: 8821139

Claim:
A fluid device comprising: a displacement assembly including: a ring having a first end face and an oppositely disposed second end face, the ring defining a bore that extends through the first and second end faces; a rotor having a first end surface and being disposed in the bore of the ring, wherein the ring and the rotor cooperatively define a plurality of volume chambers; a balance plate assembly disposed adjacent to the displacement assembly, the balance plate assembly including: a housing defining a cavity; a balance plate disposed in the cavity, the balance plate having a first end surface and an oppositely disposed second end surface, the balance plate being adapted to move axially between a first position in which the second end surface of the balance plate abuts the first end face of the ring and is spaced from the rotor first end surface to a second position in which the second end surface of the balance plate abuts the rotor first end surface and is spaced away from the ring such that the balance plate is recessed in the cavity.