Patent ID: 7402027

Claim:
A hydraulic machine comprising: a housing; a rotary group rotatably mounted within said housing, said rotary group including a barrel, a plurality of pistons axially slidable in cylinders in said barrel; a swashplate assembly to engage said pistons and induce reciprocation thereof as said barrel rotates in said housing; and a port plate interposed between said barrel and said housing, and being effective to connect respective ones of said cylinders alternatively with an inlet port and an outlet port, said port plate having a face biased into engagement with a sealing face on one of said barrel and said housing and hydraulically connected to the other of said barrel and said housing through an annular sleeve extending between and in sealing engagement with said port plate and said other of said barrel and said housing; whereby upon rotation of said barrel relative to said housing, said faces are maintained in sealing contact by said bias and fluid is transferred between one of said ports and said cylinders through said annular sleeve, misalignment between said port plate and said other of said barrel and said housing being accommodated by said annular sleeve.