Patent ID: 7150612

Claim:
A gear pump or motor comprising: a pair of gears brought in mesh with each other; shafts extending from front and rear sides of the gears in axis core directions of the respective gears; a pump main body containing the gears and the shafts, the pump main body including a front shaft containing main body and a rear shaft containing main body, said front shaft containing main body having front bearing holes for containing and supporting the shafts on the front side of the gears and the rear shaft containing main body having rear bearing holes for containing and supporting the shafts on the rear sides of the gears, said front bearing holes being independent of said rear bearing holes, said rear shaft containing main body rear bearing holes penetrating a rear face of the rear shaft containing main body; and a closing plate attached to the rear face of the rear shaft containing main body to seal a rear face region of the rear shaft containing main body in an airtight fashion from outside, wherein the rear shaft containing main body rear bearing holes open into the rear face region, said rear face region also including surroundings of the rear bearing holes, wherein a hydraulic fluid is made to flow from a high pressure region to a low pressure region of a mesh portion of the two gears.