Patent ID: 9657726
Date: 2017-05-23
CPC Classifications: F04B

Claim:
1. A running surface for connecting a rotatable pump cylinder block to a hydraulic circuit, the running surface comprising: a first kidney port having a first leading end and a first trailing end, and a second kidney port having a second leading end and a second trailing end, the first and second kidney ports each having a generally arcuate shape and a center, and defining a pitch circle passing generally through the center of the first kidney port and the center of the second kidney port; a first pressure gradient groove connected to the first kidney port and having a first proximal end connected to the first leading end, and a first distal end; a second pressure gradient groove connected to the first kidney port and having a second proximal end connected to the first trailing end, and a second distal end; a third pressure gradient groove connected to the second kidney port and having a third proximal end connected to the second leading end, and a third distal end; a fourth pressure gradient groove connected to the second kidney port and having a fourth proximal end connected to the second trailing end, and a fourth distal end; wherein the second distal end and the fourth distal end are disposed outside the pitch circle and the first distal end and the third distal end are disposed inside the pitch circle.