Patent ID: 8001777

Claim:
An axle driving apparatus comprising: a housing; an axle disposed in the housing; a hydraulic pump disposed in the housing, the hydraulic pump including a pump shaft; a hydraulic motor disposed in the housing, the hydraulic motor including a motor shaft for driving the axle; a center section disposed in the housing, the center section including upper and lower opposite horizontal surfaces, wherein the hydraulic pump is mounted on the upper horizontal surface of the center section so as to extend the pump shaft vertically; a pair of first and second horizontal linear oil passages formed in the center section between the upper and lower horizontal surfaces of the center section so as to extend parallel to each other and separately from each other and to fluidly communicate with the hydraulic motor mounted on the center section; and a pair of first and second arcuate ports which are opened on the upper horizontal surface of the center section so as to fluidly communicate with the hydraulic pump mounted thereon and are downwardly recessed in the center section, the first arcuate port having first and second end portions opposite to each other in the horizontal direction perpendicular to the first and second linear oil passages, and the second arcuate ports having third and fourth end portions opposite to each other in the horizontal direction perpendicular to the first and second linear oil passages, wherein the first arcuate port is connected at the first end portion thereof to the first linear oil passage and is not connected to the second linear oil passage, and the second arcuate port is connected at the third end portion thereof to the second linear oil passage and is not connected to the first linear oil passage, so that when viewed in the axial direction of the pump shaft, both the first and fourth end portions overlap the first linear oil passage, and both the second and third end portions overlap the second linear oil passage, wherein the first arcuate port has an intermediate portion between the first and second linear oil passages, wherein the intermediate portion has a horizontal flat bottom that is deepest in the first arcuate port and that extends from a vertically intermediate portion of the first linear oil passage, and wherein the second end portion of the first arcuate port has a bottom that extends from the horizontal flat bottom of the intermediate portion and becomes shallower until the second end portion of the first arcuate port reaches an utmost end thereof disposed above the second linear oil passage.