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A dual pump apparatus having first and second pump housings is disclosed. A first end cap is mounted to the first housing to form a first sump and a first pump cylinder block is located therein. A second end cap is mounted to the second housing to form a second sump and a second pump cylinder block

A dual pump apparatus having first and second pump housings is disclosed. A first end cap is mounted to the first housing to form a first sump and a first pump cylinder block is located therein. A second end cap is mounted to the second housing to form a second sump and a second pump cylinder block is located therein. A charge pump is sandwiched between the end caps to provide charged hydraulic fluid to one or both cylinder blocks. An input shaft having a first end external to the hydraulic pump apparatus extends into both housings to simultaneously drive the first pump cylinder block, the second pump cylinder block and the charge pump.

대표청구항 ▼

What is claimed: 1. A hydraulic pump apparatus comprising: a first end cap having a first surface and a second surface, and a first charge pump running surface formed on the second surface; a first housing mounted to the first end cap to form a first sump, wherein at least a portion of the first su

What is claimed: 1. A hydraulic pump apparatus comprising: a first end cap having a first surface and a second surface, and a first charge pump running surface formed on the second surface; a first housing mounted to the first end cap to form a first sump, wherein at least a portion of the first surface is located in the first sump; a second end cap having a third surface and a fourth surface, and a second charge pump running surface formed on the fourth surface; a second housing mounted to the second end cap to form a second sump, wherein at least a portion of the third surface is located in the second sump; and a charge pump comprising a charge pump housing separate from both end caps and located immediately adjacent to the second and fourth surfaces, wherein the charge pump is disposed on both the first and second charge pump running surfaces. 2. The hydraulic pump apparatus of claim 1, further comprising a first axial piston pump disposed on the first surface of the first end cap and within the first sump, a second axial piston pump disposed on the third surface of the second end cap and within the second sump, and a shaft directly and simultaneously driving the first axial piston pump, the second axial piston pump, and the charge pump. 3. The hydraulic pump apparatus of claim 2, further comprising a first swash plate and a first trunnion rotatable to move the first swash plate, a second swash plate and a second trunnion rotatable to move the second swash plate, wherein the first trunnion extends in a first direction from the hydraulic pump apparatus and the second trunnion extends in a second direction generally opposite the first direction. 4. The hydraulic pump apparatus of claim 2, wherein the charge pump has a first position corresponding to a first shaft rotation direction and a second position approximately 180 degrees from the first position corresponding to a second shaft rotation direction. 5. The hydraulic pump apparatus of claim 2, further comprising a fan directly driven by the shaft. 6. The hydraulic pump apparatus of claim 5, wherein the shaft is driven by a prime mover at a first end and the shaft drives the fan at a second end. 7. The hydraulic pump apparatus of claim 1, further comprising a fluid passage extending through the first end cap, the charge pump and the second end cap to connect the first sump to the second sump. 8. The hydraulic pump apparatus of claim 1, further comprising a first hydraulic circuit formed in the first end cap and a second hydraulic circuit formed in the second end cap, whereby the charge pump provides hydraulic fluid to both the first and second hydraulic circuits. 9. A hydraulic pump apparatus comprising: a first pump assembly comprising a first end cap having a first surface and a second opposite surface, a first pump cylinder block disposed on the first surface and a first housing mounted to the first end cap to form a first sump; a second pump assembly comprising a second end cap having a third surface and a fourth opposite surface, a second pump cylinder block disposed on the third surface and a second housing mounted to the second end cap to form a second sump; a charge pump positioned directly between and engaging both the second and fourth surfaces; and an input shaft comprising a first end external to the hydraulic pump apparatus and a plurality of internal portions that engage and simultaneously drive the first pump cylinder block, the second pump cylinder block and the charge pump. 10. The hydraulic pump apparatus of claim 9, further comprising a first swash plate and a first trunnion rotatable to move the first swash plate, a second swash plate and a second trunnion rotatable to move the second swash plate, wherein the first trunnion extends in a first direction from the hydraulic pump apparatus and the second trunnion extends in a second direction generally opposite the first direction. 11. The hydraulic pump apparatus of claim 9, wherein the charge pump has a first position corresponding to a first input shaft direction of rotation and a second position approximately 180 degrees from the first position corresponding to a second input shaft direction of rotation. 12. The hydraulic pump apparatus of claim 9, further comprising a fluid passage extending through the first end cap, the charge pump and the second end cap to fluidly connect the first pump assembly to the second pump assembly. 13. The hydraulic pump apparatus of claim 9, further comprising a fan directly driven by the input shaft. 14. The hydraulic pump apparatus of claim 13, wherein the input shaft is driven by a prime mover at a first end and the input shaft drives the fan at a second end. 15. A hydraulic pump apparatus comprising: a first housing and a second housing; a first end cap secured to the first housing to form a first sump, the first end cap comprising a first pump running surface, a first hydraulic circuit and a first charge pump running surface; a first hydraulic pump disposed on the first pump running surface and in fluid communication with the first hydraulic circuit; a second end cap secured to the second housing to form a second sump, the second end cap comprising a second pump running surface, a second hydraulic circuit and a second charge pump running surface; a second hydraulic pump disposed on the second pump running surface and in fluid communication with the second hydraulic circuit; a charge pump captured directly between and adjacent to the first end cap and the second end cap, wherein the charge pump is disposed on both the first and second charge pump running surfaces and provides hydraulic fluid directly to at least one of the first and second hydraulic circuits; and a fluid passage extending through the first end cap, the charge pump and the second end cap to fluidly connect the first sump directly to the second sump. 16. The hydraulic pump apparatus of claim 15, further comprising: a shaft connected to a prime mover and engaged to and driving the first hydraulic pump, the second hydraulic pump and the charge pump; and a first swash plate and a first trunnion rotatable to move the first swash plate, a second swash plate and a second trunnion rotatable to move the second swash plate, wherein the first trunnion extends in a first direction from the hydraulic pump apparatus and the second trunnion extends in a second direction generally opposite the first direction. 17. The hydraulic pump apparatus of claim 16, wherein the charge pump has a first position corresponding to a first shaft direction of rotation and a second position approximately 180 degrees from the first position corresponding to a second shaft direction of rotation. 18. The hydraulic pump apparatus of claim 16, further comprising a fan directly driven by a first end of the shaft, wherein the shaft is driven by a prime mover at a second end. 19. The hydraulic pump apparatus of claim 15, wherein the charge pump provides hydraulic fluid to both the first and second hydraulic circuits.