Patent ID: 8056670
Filing Date: 2011-11-15
Classification: A01D,B60K,B60Y,F04B,F15B

Abstract:
1. A pump unit applied to a working vehicle including a vehicle frame, a driving source supported by the vehicle frame, a pair of right and left driving wheels, and first and second hydraulic motor units that operatively drive the right and left driving wheels, respectively, the pump unit comprising, an input shaft operatively connected to an output shaft of the driving source; first and second hydraulic pump bodies that are of a variable displacement type and are fluidly connected to the first and second hydraulic motor units through a pair of first hydraulic lines and a pair of second hydraulic lines, respectively; a pump housing that accommodates the first and second hydraulic pump bodies in such a manner that they have respective rotational axis lines parallel to the input shaft; first and second pump shafts that respectively support the first and second hydraulic pump bodies in a relatively non-rotatable manner with respect thereto in a state of being operatively connected to the input shaft through a gear transmission mechanism; a PTO shaft that outputs rotational power outward that has been operatively transmitted from the input shaft; and a mounting housing that couples the pump housing with the driving source in a state that the pump housing is not directly connected to the vehicle frame, wherein the input shaft is supported by the pump housing in such a manner that the input shaft is parallel to the output shaft of the driving source, and extends outwardly from a surface of the pump housing that faces the driving source and is inserted into the mounting housing, wherein the PTO shaft is supported by the pump housing in such a manner that the PTO shaft is parallel to the input shaft and extends outwardly from a surface of the pump housing that is opposite to the surface that faces the driving source, wherein the pump housing includes a pump case that surrounds the first and second hydraulic pump bodies and has an opening on a side opposite to a side that faces the mounting housing, the opening having a size that allows the first and second hydraulic pump bodies to pass therethrough, and a center section that is connected to the pump case so as to close the opening, wherein the pump unit further comprises a charge pump unit arranged at a surface of the center section that is opposite to a surface that faces the pump case, the charge pump unit being operatively driven by rotational power that is operatively transmitted from the input shaft and supplying charge fluid to a first HST and a second HST, the first HST being formed by the first hydraulic pump body and the first hydraulic motor unit and the second HST being formed by the second hydraulic pump body and the second hydraulic motor unit, wherein the pump unit further comprises a hydraulic clutch mechanism arranged between the input shaft and the PTO shaft with respect to a power transmission direction, the hydraulic clutch mechanism being operated using a part of pressurized fluid from the charge pump unit as a hydraulic source to selectively engage or disengage power transmission from the input shaft to the PTO shaft, wherein the PTO shaft is arranged coaxially with the input shaft, and wherein the input shaft is supported by the pump housing in such a manner that the input shaft is arranged coaxially with the output shaft of the driving source that is extended horizontally, the input shaft being connected with the output shaft in a relatively non-rotatable manner around an axis line within the mounting housing when the pump housing is coupled with the driving source through the mounting housing.