HST unit

An HST unit includes a first hydraulic motor unit for operatively driving one of a pair of driving wheels; a second hydraulic motor unit for operatively driving the other one of the pair of driving wheels; a hydraulic pump unit operatively connected to a driving power source, the hydraulic pump unit configuring a traveling hydrostatic transmission in cooperation with the first and second hydraulic motor units; and an attachment frame for supporting the first hydraulic motor unit, the second hydraulic motor unit and the hydraulic pump unit, the attachment frame being attachable to a vehicle frame.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an HST unit including a pair of hydraulic motor units, each hydraulic motor unit being independently arrangeable, and a hydraulic pump unit forming a traveling hydrostatic transmission in cooperation with the pair of hydraulic motor units.

2. Related Art

It has been conventionally known to form a traveling hydrostatic transmission by fluidly connecting the hydraulic pump unit and the hydraulic motor unit, which are arranged spaced apart from each other, by way of a conduit.

Such a configuration is particularly useful in a working vehicle that needs provide a space between a pair of driving wheels so as to stabilize the body posture at the time of turning such as a mower tractor capable of turning in place (zero turn) (for example, see U.S. Pat. No. 6,425,244).

However, with the conventional configuration, the hydraulic pump unit and the hydraulic motor unit have to be independently attached to the vehicle main body, and then be connected by the conduit, in the assembly work to the vehicle main body, resulting in poor assembly workability.

Furthermore, the adjustment work of the traveling hydrostatic transmission configured by the hydraulic pump unit and the hydraulic motor units is desirably performed in a state where the hydraulic pump unit and the hydraulic motor unit are fluidly connected according to the usage conditions. However, with the conventional configuration, such adjustment work can only be performed after the hydraulic pump unit and the hydraulic motor units are attached to the vehicle main body.

Furthermore, in the conventional configuration, the driving power source, which is the power source of the hydraulic pump unit, has to be attached to the vehicle main body independent from the hydraulic pump unit and the hydraulic motor units.

Moreover, in some specified cases, a reservoir tank that is an oil source of the operational fluid in the traveling hydrostatic transmission may be provided. However, with the conventional configuration, the attachment of the reservoir tank to the vehicle main body also has to be performed independent from the hydraulic pump unit and the hydraulic motor units.

In view of the conventional techniques, a first aspect of the present invention aims to provide an HST unit that enhances the efficiency of the conduit connecting work, the adjustment work, and the attachment work to the vehicle main body, of the hydraulic pump unit and the hydraulic motor units configuring the traveling hydrostatic transmission.

Further, a second aspect of the present invention aims to provide an HST unit that enhances the efficiency of the conduit connecting work, the adjustment work, and the attachment work to the vehicle main body, of the hydraulic pump unit and the hydraulic motor units configuring the traveling hydrostatic transmission, as well as the efficiency of the attachment work of a driving power source, which is a power source of the hydraulic pump unit, to the vehicle main body, and the efficiency of the connecting work between the power source and the hydraulic pump unit.

Furthermore, a third aspect of the present invention aims to provide an HST unit that enhances the efficiency of the conduit connecting work, the adjustment work, and the attachment work to the vehicle main body, of the hydraulic pump unit and the hydraulic motor units configuring the traveling hydrostatic transmission, as well as the efficiency of the attachment work of a reservoir tank, which is an oil source for operational fluid in the traveling hydrostatic transmission, to the vehicle main body, and the efficiency of the conduit connecting work between the reservoir tank and the traveling hydrostatic transmission.

SUMMARY OF THE INVENTION

The first aspect of the present invention provides an HST unit including: a first hydraulic motor unit for operatively driving one of a pair of driving wheels; a second hydraulic motor unit for operatively driving the other one of the pair of driving wheels; a hydraulic pump unit operatively connected to a driving power source, the hydraulic pump unit configuring a traveling hydrostatic transmission in cooperation with the first and second hydraulic motor units; and an attachment frame for supporting the first hydraulic motor unit, the second hydraulic motor unit and the hydraulic pump unit, the attachment frame being attachable to a vehicle frame.

According to the configuration, it is possible to complete the attachment work of the traveling hydrostatic transmission to the vehicle main body, by having the hydraulic pump unit, the first hydraulic motor unit, and the second hydraulic motor unit configuring the traveling hydrostatic transmission mounted to the attachment frame in advance, and then attaching the attachment frame to the vehicle frame. Therefore, the attachment work of the hydraulic pump unit, the first hydraulic motor unit, and the second hydraulic motor unit to the vehicle main body becomes more efficient.

Further, the conduit connecting work between the hydraulic pump unit and the first and second hydraulic motor units can be performed before attaching these hydraulic units to the vehicle main body. Therefore, the conduit connecting work becomes more efficient, and the adjusting work of the traveling hydrostatic transmission could be performed irrespective of the vehicle main body, thereby improving the efficiency of the adjusting work. The effects are particularly effective in a case where the hydraulic equipment manufacturing company manufactures the hydraulic pump unit, the first hydraulic motor unit and the second hydraulic motor unit, and the vehicle manufacturing company attaches the hydraulic units to the vehicle frame to complete the working vehicle.

Further, the maintenance and replacing of the hydraulic units are easily carried out, since the hydraulic pump unit, the first hydraulic motor unit and the second hydraulic motor unit are independently supported by the attachment frame.

In one embodiment, the hydraulic pump unit may include: an input shaft operatively connected to the driving power source; first and second hydraulic pump main bodies operatively driven by a power from the input shaft; and a pump case for accommodating the first and second hydraulic pump main bodies, the pump case including a first hydraulic pump-side operational fluid passage having a first end fluidly connected to the first hydraulic pump main body and a second end opened to the outer surface and a second hydraulic pump-side operational fluid passage having a first end fluidly connected to the second hydraulic pump main body and a second end opened to the outer surface. The first hydraulic motor unit may include: a first motor shaft for operatively driving the one driving wheel; a first hydraulic motor main body for rotatably driving the first motor shaft; and a first motor case for accommodating the first hydraulic motor main body, the first motor case including a first hydraulic motor-side operational fluid passage having a first end fluidly connected to the first hydraulic motor main body and a second end opened to the outer surface. The second hydraulic motor unit may include: a second motor shaft for operatively driving the other driving wheel; a second hydraulic motor main body for rotationally driving the second motor shaft; and a second motor case for accommodating the second hydraulic motor main body, the second motor case including a second hydraulic motor-side operational fluid passage having a first end fluidly connected to the second hydraulic motor main body and a second end opened to the outer surface. In the embodiment, the HST unit further includes: a first operational fluid conduit for fluidly connecting the first hydraulic pump-side operational fluid passage and the first hydraulic motor-side operational fluid passage; and a second operational fluid conduit for fluidly connecting the second hydraulic pump-side operational fluid passage and the second hydraulic motor-side operational fluid passage. The first and second operational fluid conduits are supported by the attachment frame.

In another embodiment, the hydraulic pump unit may include first and second hydraulic pump units independently arranged with respect to each other. Each of the first and second pump units includes: an input shaft operatively connected to the driving power source; a hydraulic pump main body operatively driven by a power from the input shaft; and a pump case for accommodating the hydraulic pump main body, the pump case including a hydraulic pump-side operational fluid passage having a first end fluidly connected to the hydraulic pump main body and a second end opened to the outer surface. The first hydraulic motor unit may include: a first motor shaft for operatively driving the one driving wheel; a first hydraulic motor main body for rotationally driving the first motor shaft; and a first motor case for accommodating the first hydraulic motor main body, the first motor case including a first hydraulic motor-side operational fluid passage having a first end fluidly connected to the first hydraulic motor main body and a second end opened to the outer surface. The second hydraulic motor unit may include: a second motor shaft for operatively driving the other driving wheel; a second hydraulic motor main body for rotationally driving the second motor shaft; and a second motor case for accommodating the second hydraulic motor main body, the second motor case including a second hydraulic motor-side operational fluid passage having a first end fluidly connected to the second hydraulic motor main body and a second end opened to the outer surface. In the embodiment, the HST unit further includes a first operational fluid conduit for fluidly connecting the hydraulic pump-side operational fluid passage in the first pump unit and the first hydraulic motor-side operational fluid passage; and a second operational fluid conduit for fluidly connecting the hydraulic pump-side operational fluid passage in the second pump unit and the second hydraulic motor-side operational fluid passage. The first and second operational fluid conduits are supported by the attachment frame.

In still another embodiment, the hydraulic pump unit may include: an input shaft operatively connected to the driving power source; a traveling hydraulic pump main body operatively driven by a power from the input shaft; and a pump case for accommodating the traveling hydraulic pump main body, the pump case including a hydraulic pump-side operational fluid passage having a first end fluidly connected to the traveling hydraulic pump main body and a second end opened to the outer surface. The first hydraulic motor unit may include: a first motor shaft for operatively driving the one driving wheel; a first hydraulic motor main body for rotationally driving the first motor shaft; and a first motor case for accommodating the first hydraulic motor main body, the first motor case including a first hydraulic motor-side operational fluid passage having a first end fluidly connected to the first hydraulic motor main body and a second end opened to the outer surface. The second hydraulic motor unit may include: a second motor shaft for operatively driving the other driving wheel; a second hydraulic motor main body for rotationally driving the second motor shaft; and a second motor case for accommodating the second hydraulic motor main body, the second motor case including a second hydraulic motor-side operational fluid passage having a first end fluidly connected to the second hydraulic motor main body and a second end opened to the outer surface. In the embodiment, the HST unit further includes: a motor-side conduit for fluidly connecting the first and second hydraulic motor-side operational fluid passages; and a operational fluid conduit for fluidly connecting the hydraulic pump-side operational fluid passage and the motor-side conduit. The motor-side conduit and the operational fluid conduit are supported by the attachment frame.

Preferably, the hydraulic pump unit further includes another hydraulic pump main body accommodated in the pump case so as to be operatively driven by the power from the input shaft.

In the above various configurations, the attachment frame preferably has a gate shape when seen from the front, and includes first and second motor supporting surfaces positioned on one side and the other side in the vehicle width direction, and a pump supporting surface positioned above the first and second motor supporting surfaces and positioned between the first and second motor supporting surfaces in the vehicle width direction, in a state of being attached to the vehicle frame.

For example, the pump supporting surface extends horizontally so that a rotational axis line of the hydraulic pump main body lies in the vertical direction, in a state where the attachment frame is attached to the vehicle frame.

Alternatively, the pump supporting surface extends vertically so that a rotational axis line of the hydraulic pump main body lies in the horizontal direction, in a state where the attachment frame is attached to the vehicle frame.

Preferably, the attachment frame includes a supporting surface integrally extending downward from the pump supporting surface, the supporting surface supporting a PTO clutch device interposed in a PTO system transmission path from the driving power source to a working machine.

In the above various configurations, the hydraulic pump unit preferably further includes a PTO shaft for externally outputting the rotational power from the input shaft.

The second aspect of the present invention provides an HST unit including; a first hydraulic motor unit for operatively driving one of a pair of driving wheels; a second hydraulic motor unit for operatively driving the other one of the pair of driving wheels; a hydraulic pump unit operatively connected to a driving power source, the hydraulic pump unit configuring a traveling hydrostatic transmission in cooperation with the first and second hydraulic motor units; and an attachment frame for supporting the driving power source, the first hydraulic motor unit, the second hydraulic motor unit and the hydraulic pump unit, the attachment frame being attachable to a vehicle frame.

In one embodiment, the attachment frame integrally includes a first side plate positioned on one side in the vehicle width direction, a second side plate positioned on the other side in the vehicle width direction, and a top plate lying substantially horizontally between the first and second side plates, in a state of being attached to the vehicle frame. The first and second side plates support the first and second hydraulic motor units, respectively. The top plate supports the driving power source and the hydraulic pump unit so that a driving shaft of the driving power source and an input shaft of the hydraulic pump shaft are directed substantially vertically.

In another embodiment, the attachment frame integrally include a first side plate positioned on one side in the vehicle width direction, a second side plate positioned on the other side in the vehicle width direction, a first connecting plate extending in the vehicle width direction in a state of lying substantially vertically so as to connect between the first and second side plates, and a top plate lying substantially horizontally between the first and second side plates, in a state of being attached to the vehicle frame. The first and second side plates support the first and second hydraulic motor units, respectively. The first connecting plate supports the hydraulic pump unit so that an input shaft of the hydraulic pump shaft is directed substantially horizontally. The top plate supports the driving power source so that a driving shaft of the driving power source is directed substantially horizontally.

In the above various embodiments, preferably, the HST unit further includes a reservoir tank that is an oil source for operational fluid of the traveling hydrostatic transmission. The reservoir tank is supported by the top plate.

More preferably, the HST unit further includes a filter unit for filtering oil supplied from the reservoir tank to the traveling hydrostatic transmission, the filter unit being separate from the reservoir tank. The filter unit is supported by the top plate.

Alternatively, the reservoir tank may include therein a filter unit for filtering oil supplied from the reservoir tank to the traveling hydrostatic transmission.

The third aspect of the present invention provides an HST unit including: a first hydraulic motor unit for operatively driving one of a pair of driving wheels; a second hydraulic motor unit for operatively driving the other one of the pair of driving wheels; a hydraulic pump unit operatively connected to a driving power source, the hydraulic pump unit configuring a traveling hydrostatic transmission in cooperation with the first and second hydraulic motor units; a reservoir tank that is an oil source for operational fluid of the traveling hydrostatic transmission; and an attachment frame for supporting the first hydraulic motor unit, the second hydraulic motor unit, the hydraulic pump unit and the reservoir tank, the attachment frame being attachable to a vehicle frame.

In the above various configurations of the second and third aspects of the present invention, the hydraulic pump unit may include: an input shaft operatively connected to the driving power source; first and second hydraulic pump main bodies operatively driven by a power from the input shaft; and a pump case for accommodating the first and second hydraulic pump main bodies, the pump case having a pump-side operational fluid passage that includes a first hydraulic pump-side operational fluid passage having a first end fluidly connected to the first hydraulic pump main body and a second end opened to the outer surface and a second hydraulic pump-side operational fluid passage having a first end fluidly connected to the second hydraulic pump main body and a second end opened to the outer surface. The first hydraulic motor unit includes: a first motor shaft for operatively driving the one driving wheel; a first hydraulic motor main body for rotatably driving the first motor shaft; and a first motor case for accommodating the first hydraulic motor main body, the first motor case including a first hydraulic motor-side operational fluid passage having a first end fluidly connected to the first hydraulic motor main body and a second end opened to the outer surface. The second hydraulic motor unit includes: a second motor shaft for operatively driving the other driving wheel; a second hydraulic motor main body for rotationally driving the second motor shaft; and a second motor case for accommodating the second hydraulic motor main body, the second motor case including a second hydraulic motor-side operational fluid passage having a first end fluidly connected to the second hydraulic motor main body and a second end opened to the outer surface. The HST unit further includes: a first operational fluid conduit for fluidly connecting the first hydraulic pump-side operational fluid passage and the first hydraulic motor-side operational fluid passage; and a second operational fluid conduit for fluidly connecting the second hydraulic pump-side operational fluid passage and the second hydraulic motor-side operational fluid passage. The first and second operational fluid conduits are supported by the attachment frame.

Alternatively, the hydraulic pump unit may include first and second hydraulic pump units independently arranged with respect to each other. Each of the first and second pump units each includes: an input shaft operatively connected to the driving power source; a hydraulic pump main body operatively driven by a power from the input shaft; and a pump case for accommodating the hydraulic pump main body, the pump case including a hydraulic pump-side operational fluid passage having a first end fluidly connected to the hydraulic pump main body and a second end opened to the outer surface. The first hydraulic motor unit includes: a first motor shaft for operatively driving the one driving wheel; a first hydraulic motor main body for rotationally driving the first motor shaft; and a first motor case for accommodating the first hydraulic motor main body, the first motor case including a first hydraulic motor-side operational fluid passage having a first end fluidly connected to the first hydraulic motor main body and a second end opened to the outer surface. The second hydraulic motor unit includes: a second motor shaft for operatively driving the other driving wheel; a second hydraulic motor main body for rotationally driving the second motor shaft; and a second motor case for accommodating the second hydraulic motor main body, the second motor case including a second hydraulic motor-side operational fluid passage having a first end fluidly connected to the second hydraulic motor main body and a second end opened to the outer surface. The HST unit further includes: a first operational fluid conduit for fluidly connecting the hydraulic pump-side operational fluid passage in the first pump unit and the first hydraulic motor-side operational fluid passage; and a second operational fluid conduit for fluidly connecting the hydraulic pump-side operational fluid passage in the second pump unit and the second hydraulic motor-side operational fluid passage. The first and second operational fluid conduits are supported by the attachment frame.

Alternatively, the hydraulic pump unit may include: an input shaft operatively connected to the driving power source; a traveling hydraulic pump main body operatively driven by a power from the input shaft; and a pump case for accommodating the traveling hydraulic pump main body, the pump case including a hydraulic pump-side operational fluid passage having a first end fluidly connected to the traveling hydraulic pump main body and a second end opened to the outer surface. The first hydraulic motor unit includes: a first motor shaft for operatively driving the one driving wheel; a first hydraulic motor main body for rotationally driving the first motor shaft; and a first motor case for accommodating the first hydraulic motor main body, the first motor case including a first hydraulic motor-side operational fluid passage having a first end fluidly connected to the first hydraulic motor main body and a second end opened to the outer surface. The second hydraulic motor unit includes: a second motor shaft for operatively driving the other driving wheel; a second hydraulic motor main body for rotationally driving the second motor shaft; and a second motor case for accommodating the second hydraulic motor main body, the second motor case including a second hydraulic motor-side operational fluid passage having a first end fluidly connected to the second hydraulic motor main body and a second end opened to the outer surface. The HST unit further includes: a motor-side conduit for fluidly connecting the first and second hydraulic motor-side operational fluid passages; and a operational fluid conduit for fluidly connecting the hydraulic pump-side operational fluid passage and the motor-side conduit. The motor-side conduit and the operational fluid conduit are supported by the attachment frame.

Preferably, the hydraulic pump unit further includes another hydraulic pump main body accommodated in the pump case so as to be operatively driven by the power from the input shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

The first preferred embodiment of the HST unit according to the present invention will now be described with reference to the accompanied drawings.

FIG. 1andFIG. 2are a side view and a partial rear view, respectively, of a working vehicle1A to which the HST unit100A according to the present embodiment is applied.

As shown inFIG. 1andFIG. 2, the working vehicle1A includes a vehicle frame30, a driving power source40A supported by the vehicle frame30, the HST unit100A configuring the traveling hydrostatic transmission, a traveling system power transmission mechanism10A for transmitting the power from the driving power source40A to the HST unit100A, a pair of first driving wheel50aand second driving wheel50b(rear wheels in the present embodiment), and caster wheels60(front wheels in the present embodiment).

In the present embodiment, the working vehicle1A is of a rear discharge type riding lawn mower.

That is, the working vehicle1A further includes a driver's seat35, a working machine70(mower device in the present embodiment) suspended and supported between the driving wheels50and the caster wheels60in a state capable of lifting upwardly and downwardly, a PTO system power transmission mechanism20A for transmitting the power from the driving power source40A to the working machine70, and a duct80for guiding the grass cut by the working machine70to a grass collecting bag (not shown) arranged at the back of the vehicle body.

The HST unit100A is configured so as to form the traveling hydrostatic transmission while providing a free space between the pair of driving wheels50a,50b.

Specifically, as shown inFIG. 1andFIG. 2, the HST unit100A includes: first hydraulic motor unit200afor operatively driving the first driving wheel50a; a second hydraulic motor unit200bfor operatively driving the second driving wheel50b; a hydraulic pump unit300A operatively connected to the driving source40A, the hydraulic pump unit300A being fluidly connected to the first and second hydraulic motor units200a,200b; and an attachment frame500A for supporting the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200bso as to define a free space between the first and second driving wheels50a,50b.

At least one of the hydraulic pump unit300A, and the first and second hydraulic motor units200a,200bis (are) of a variable displacement type.

In the present embodiment, the hydraulic pump unit300A is of the variable displacement type, and the first and second hydraulic motor units200a,200bare of the fixed displacement type.

FIG. 3shows a vertical sectional rear view in the vicinity of the first hydraulic motor unit200a.

The second hydraulic motor unit200bhas substantially the same configuration as that of the first hydraulic motor unit200a.

Therefore, the corresponding members of the second hydraulic motor unit200bare designated by the same reference numerals or the same reference numerals with replacing subscript with b as those of the first hydraulic motor unit200a, and thus the detailed description thereof is omitted.

As shown inFIG. 3, the first hydraulic motor unit200ais configured so as to operatively drive the corresponding first driving wheel50a.

Specifically, the first hydraulic motor unit200aincludes a first hydraulic motor main body210a, a first motor shaft220arotationally driven about the axis line by the first hydraulic motor main body210a, and a first motor case230afor accommodating the first hydraulic motor main body210aand for supporting the first motor shaft220ain a rotatable manner about the axis line.

The first motor case230aincludes a motor case main body240ahaving an opening, through which the first hydraulic motor main body210acan be inserted, formed on the first end face (end face facing inward in the vehicle width direction in a state mounted to the vehicle frame30in the present embodiment), and a first motor-side port block250a(first motor-side center section) coupled to the motor case main body240aso as to close the opening.

The first motor-side port block250ais provided with a pair of first hydraulic motor-side operational fluid passages255ahaving first ends fluidly connected to the first hydraulic motor main body210aand second ends opened to the outer surface.

The second ends of the pair of first hydraulic motor-side operational fluid passages255aform first hydraulic motor-side operational fluid ports255a(P) which act as fluid connecting ports to the first hydraulic pump main body310a, to be hereinafter described.

The first motor shaft220ahas a first end operatively connected to a driving axle51for the first driving wheel50a.

Preferably, the first motor shaft220ais operatively connected to the corresponding driving axle51via a reduction transmission mechanism55, as shown inFIG. 3.

With the reduction transmission mechanism55, capacity of the first hydraulic motor main body210acould be made smaller.

In this embodiment, a planetary gear mechanism is employed as the reduction transmission mechanism55, and the corresponding motor shaft and the vehicle shaft are concentrically arranged. Alternatively, it is possible to have the corresponding motor shaft and the driving axle off set to each other, and employ one or a plurality of gear trains arranged on the two axle arranged parallel to each other as the reduction transmission mechanism.

Further, the reduction transmission mechanism55may be omitted by increasing the capacity of the first hydraulic motor main body210a.

In the present embodiment, the first hydraulic motor unit200ahas, in addition to the above configuration, a brake mechanism270that selectively applies a braking force to the first motor shaft220a.

Specifically, the first motor shaft220ahas a second end (end opposite the first end operatively connected to the first driving wheel50a) extending outward from the first motor-side port block250a.

The brake mechanism270is configured so as to selectively apply the braking force to the second end of the first motor shaft220based on external operation.

The brake mechanism270is of an internal expanding type in the present embodiment.

Specifically, the brake mechanism270includes a brake drum271supported in a relatively non-rotatable manner at the second end of the first motor shaft220a, a brake shoe272arranged facing the inner peripheral surface of the brake drum271, a biasing member273for biasing the brake shoe272in a direction away from the inner peripheral surface of the brake drum271, and a brake operation arm274for pushing the brake shoe272toward the inner peripheral surface of the brake drum271against the biasing force of the biasing member273.

Although the inner expanding brake device is adopted as the brake mechanism270in the present embodiment, other brake devices such as a disc brake device could obviously be used.

FIG. 4shows a vertical sectional rear view in the vicinity of the hydraulic pump unit300A.

In the present embodiment, the hydraulic pump unit300A includes a first hydraulic pump main body310aand a second hydraulic pump main body310bthat are fluidly connected to the first hydraulic motor main body210aand the second hydraulic motor main body (not shown), respectively. Herein, the first and second hydraulic pump main bodies310a,310bare accommodated in a single pump case330A, as shown inFIG. 4.

Specifically, the hydraulic pump unit300A includes an input shaft370operatively connected to the driving power source40A, first and second pump shafts320a,320b, a transmission mechanism380for transmitting the power from the input shaft370to the first and second pump shafts320a,320b, the first and second hydraulic pump main bodies310a,310bthat are supported in a relatively non-rotatable manner at the first and second pump shafts320a,320b, respectively, and a pump case330A for accommodating the first and second hydraulic pump main bodies310a,310band for supporting the input shaft370, and the first and second pump shafts320a,320bin a rotatable manner about the respective axis line.

In the present embodiment, the hydraulic pump unit300A is of a variable displacement type, as mentioned above.

Therefore, the hydraulic pump unit includes first and second capacity adjusting mechanisms450a,450bfor respectively changing the supply/suction amount of the first and second hydraulic pump main bodies310a,310bbased on external operation, in addition to the above configuration.

The first and second capacity adjusting mechanisms450a,450beach includes an output adjusting member460(seeFIG. 4) such as a movable swash plate for changing the supply/suction amount of the corresponding hydraulic pump main body310, and a control shaft470(seeFIG. 1) for tilting the output adjusting member460based on external operation.

Each control shaft470of the first and second capacity adjusting mechanisms450a,450bis operatively connected to a pair of steering levers36a,36b, respectively, arranged at the front of the driver's seat35by way of appropriate link mechanisms37a,37b(seeFIG. 1).

The pump case330A includes a pump case main body340A, a pump-side port block350A (pump-side center section) detachably coupled to the pump case main body340A, and a lid member360A detachably coupled to the pump case main body340A.

As shown inFIG. 4, the pump case main body340A has an end wall341A that extends in a direction substantially orthogonal to the axis line direction of the pump shafts320a,320b, and a peripheral wall342A extending in the axis line direction of the pump shafts320a,320bfrom the peripheral edge of the end wall341A.

The peripheral wall342has an opening at a free end side opposite the end wall341a.

The opening is sized to allow the first and second hydraulic pump main bodies310a,310bto be inserted.

The pump-side port block350A is coupled to the pump case main body340A so as to close the opening.

In other words, a pump accommodating space for accommodating the first and second hydraulic pump main bodies310a,310bis defined by the end wall341A and the peripheral wall342A of the pump case main body340A, and the pump-side port block350A.

The pump-side port block350A is provided with a pair of first hydraulic pump-side operational fluid passages355ahaving first ends fluidly connected to the first hydraulic pump main body310aand second ends opened to the outer surface, and a pair of second hydraulic pump-side operational fluid passages355bhaving first ends fluidly connected to the second hydraulic pump main body310band second ends opened to the outer surface.

The second ends of the pair of first hydraulic pump-side operational fluid passages355aform first hydraulic pump-side operational fluid ports355a(P) which act as the fluid connecting ports to the first hydraulic motor main body210a(seeFIG. 2).

The second ends of the pair of second hydraulic pump-side operational fluid passages355bform second hydraulic pump-side operational fluid ports355b(P) which act as the fluid connecting ports to the second hydraulic motor main body (seeFIG. 2).

The lid member360A is coupled to the pump case main body340A so as to define a transmission mechanism accommodating space for accommodating the transmission mechanism380in cooperation with the end wall341A.

The input shaft370is supported by the pump case330A so that one end forming the input end extends outward.

The first and second pump shafts320a,320bare supported at the both ends by the lid member360A and the pump-side port block350A so as to support the corresponding hydraulic pump main bodies310a,310bwithin the pump accommodating space.

The transmission mechanism380is configured to transmit the power from the input shaft370to the first and second pump shafts320a,320b.

In the present embodiment, the first pump shaft320aand the input shaft370are integrally formed by a single shaft325, as shown inFIG. 4.

Therefore, the transmission mechanism380includes a driving gear381supported in a relatively non-rotatable manner at the single shaft325, and a driven gear382supported in a relatively non-rotatable manner at the second pump shaft320bso as to engage with the driving gear381.

Preferably, one of or both of the first and second pump shafts320a,320bhas (have) at least one end extending outward from the pump case330A.

The projecting end is used as the driving shaft for the charge pump main body annexed to the hydraulic pump unit300aor other rotating members, as desired.

In the present embodiment, the input shaft370and the first pump shaft320aare integrally formed by the single shaft325, as explained above.

As shown inFIG. 4, the single shaft325has a first end passing through the lid member360A and projecting outward to form the input end, and a second end passing through the pump-side port block350A and extending outward.

The second end of the single shaft325acts as the driving shaft for a charge pump main body410that is to be hereinafter described.

In the present embodiment, the second pump shaft320balso has a second end passing through the pump-side port block350A and extending outward so as to externally output the rotational power, as shown inFIG. 4.

A cooling fan and the like may be arranged at the second end of the second pump shaft320b.

In the present embodiment, the hydraulic pump unit300A includes a charge pump unit400, in addition to the above configuration.

The charge pump unit includes a charge pump main body410operatively driven by the rotational power of the input shaft370, and a charge pump case420surrounding the charge pump main body410, as shown inFIG. 4.

In the present embodiment, the charge pump main body410is configured so as to be driven by the second end of the single shaft325.

The charge pump case420is coupled to the pump-side port block350A so as to surround the charge pump main body410.

The attachment frame500A supports the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200b, and is attachable to the vehicle frame30in a state of providing a free space between the first and second driving wheels50a,50b.

Specifically, the attachment frame500A has a gate shape when seen from the front, and includes a first motor supporting surface510aarranged on one side in the vehicle width direction so as to be positioned in the vicinity of the first driving wheel50a, a second motor supporting surface510barranged on the other side in the vehicle width direction so as to be positioned in the vicinity of the second driving wheel50b, and a pump supporting surface520positioned above the first and second motor supporting surfaces510a,510band positioned between the first and second motor supporting surfaces510a,510bwith respect to the vehicle width direction, in a state attached to the vehicle frame30, as shown inFIG. 2.

In the HST unit100A having the thus constructed attachment frame500A, it is possible to complete the attachment work of the hydraulic pump unit300A and the first and second hydraulic motor units200a,200bto the vehicle frame30while providing the free space between the first and second driving wheels50a,50b, by attaching the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200bconfiguring the traveling hydrostatic transmission to the attachment frame500A in advance, and then attaching the attachment frame500A to the vehicle frame30.

Therefore, the efficiency of the assembly work of the vehicle could be enhanced.

Further, the HST100A is so configured that the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200bare independently supported by the attachment frame500A. Therefore, the replacing work and the maintenance work of the hydraulic units can be easily carried out.

Furthermore, in the HST unit100a, the conduit connecting work between the first and second hydraulic pump main bodies310a,310b, and the first and second hydraulic motor main bodies210a,210bcan also be carried out without assembling the hydraulic pump unit300A as well as the first and second hydraulic motor units200a,200bto the vehicle frame30.

In other words, in the HST100A, it is possible to complete the connecting work between the first hydraulic pump main body310aand the first hydraulic motor main body210aby fluidly connecting the first hydraulic pump-side operational fluid ports355a(P) and the first hydraulic motor-side operational fluid ports255a(P) by means of the first operational fluid conduit480a; and complete the connecting work between the second hydraulic pump main body310band the second hydraulic motor main body by fluidly connecting the second hydraulic pump-side operational fluid ports355a(P) and the second hydraulic motor-side operational fluid ports255b(P) by means of the second operational fluid conduit480b, in a state where the hydraulic pump unit300A as well as the first and second hydraulic motor units200a,200bare attached only to the attachment frame500A, without attaching to the vehicle frame.

That is, in the HST unit100A, the conduit connecting work could be carried out irrespective of the assembly work to the vehicle frame.

The first operational fluid conduit480aand the second operational fluid conduit480bare preferably supported by the attachment frame500A, as shown inFIG. 2.

Further, the adjustment work of the traveling hydrostatic transmission configured by the hydraulic pump unit300A as well as the first and second hydraulic motor units200a,200bcould be more efficient in the HST unit100A.

Specifically, in the HST unit100A, it is possible that the first and second hydraulic pump main bodies310a,310band the first and second hydraulic motor main bodies are fluidly connected in a state corresponding to the usage state before attaching the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200bto the vehicle frame30, as explained above.

Therefore, the adjustment work of the traveling hydrostatic transmission could be carried out irrespective of the vehicle main body.

In particular, in a case where the hydraulic equipment manufacturing company manufactures the hydraulic pump unit and the hydraulic motor unit, and the vehicle manufacturing company attaches the hydraulic pump unit and the hydraulic motor unit to the vehicle frame and completes the working vehicle, the HST unit100A allows the hydraulic equipment manufacturing company to carry out the adjustment work of the hydraulic pump unit and the hydraulic motor unit in a state corresponding to the vehicle mounted state before shipment of the traveling hydrostatic transmission. Therefore, the vehicle manufacturing company could assemble the traveling hydrostatic transmission to the vehicle frame, such that the work of attaching the attachment frame to the vehicle frame is extremely simple.

Further, the attachment frame500A is configured so as to have the first and second motor supporting surfaces510a,510bpositioned respectively at one side and the other side in the vehicle width direction and have a gate shape when seen from the front, in a state of being attached to the vehicle frame30, as described above.

Therefore, the pair of hydraulic motor units200a,200bcan be arranged in a distributed manner in the vehicle width direction, and the free space can be secured between the driving wheels50a,50bby simply attaching the attachment frame500A to the vehicle frame30.

Such effect is particularly effective in the working vehicle, for example, needing to stabilize the body posture at the time of turning in place (zero turn).

In the working vehicle, a PTO system power transmission mechanism20A and the duct80are arranged in the free space, as shown inFIG. 2.

In the working vehicle1A, the driving power source40A is of a vertical crank shaft type, and the traveling system power transmission mechanism10A and the PTO system power transmission mechanism20A are both of pulley-belt mechanism, as shown inFIG. 1andFIG. 2.

Specifically, the driving power source40A is supported by the vehicle frame30by way of a flat plate45arranged on the rear side of the vehicle frame30so that the driving shaft41lies in the vertical direction.

An opening through which the driving shaft41is inserted is formed in the flat plate45.

The driving power source40A is mounted on the upper surface of the flat plate45so that the shaft end of the driving shaft41is positioned below the flat plate45through the opening.

Preferably, the flat plate45is supported by the vehicle frame30by way of elastic members46, so that vibration from the driving power source40A is effectively prevented from transmitting to the vehicle frame30.

The traveling system power transmission mechanism10A includes a travel driving pulley11attached to the driving shaft41of the driving power source40A so as to be positioned below the flat plate45, a travel driven pulley12attached to the input shaft370of the hydraulic pump unit300A, and a travel belt13wound around the travel driving pulley11and the travel driven pulley12.

The PTO system power transmission mechanism20A includes a working machine driving pulley21attached to the driving shaft41of the driving power source40A so as to be positioned below the flat plate45, a working machine driven pulley22attached to the input shaft of the working machine70, and a working machine belt23wound around the working machine driving pulley21and the working machine driven pulley22.

In order to simplify the connecting structure between the vertical crank shaft type driving power source40A and the hydraulic pump unit300A, the pump supporting surface520is configured so as to support the hydraulic pump unit300A with the input shaft370lying in the vertical direction in a state where the attachment frame500A is attached to the vehicle frame30in the present embodiment.

Specifically, the attachment frame500A includes a first side plate550aextending substantially vertically on one side in the vehicle width direction so as to face the first driving wheel50a, a second side plate550bextending substantially vertically on the other side in the vehicle width direction so as to face the second driving shaft50b, a top plate560being substantially horizontally above the first and second side plates550a,550band at the center in the vehicle width direction, and a connecting plate570extending substantially vertically so as to connect the first and second side plates550a,550band the top plate560, with the state attached to the vehicle frame30as the reference, as shown inFIG. 2.

The top plate560configures the pump supporting surface520, and the first and second side plates550a,550bconfigure the first and second motor supporting surfaces510a,510b, respectively.

The connecting plate570has a gate shape when seen from the front, and includes a first portion570aextending upward from the first side plate550a, a second portion570bextending upward from the second side plate550b, and a connecting portion570cconnecting the upper parts of the first portion570aand the second portion570b, as shown inFIG. 2, so that the strength of the attachment frame500A is ensured while providing the free space between the first and second driving wheels50a,50b.

As shown inFIG. 2, an opening is formed at the top plate560, and the hydraulic pump unit300A is supported on the upper surface of the top plate560with the input shaft370extending downward through the opening.

The travel driven pulley12is attached to the input shaft370below the top plate560.

Second Embodiment

The second embodiment of the HST unit according to the present invention will now be described with reference to the accompanied drawings.

FIG. 5andFIG. 6are a side view and a partial rear view, respectively, of a working vehicle1B to which the HST unit100B according to the present embodiment is applied.

In the figure, the same reference characters are denoted for the members that are the same as those in the first embodiment, and thus the explanation thereof is omitted.

The HST unit100B according to the present embodiment is configured so as to be applied to the working vehicle1B including a horizontal crank shaft type driving power source40B.

Specifically, the working vehicle1B includes the vehicle frame30, a driving power source40B supported by the vehicle frame30, the HST unit100B according to the present embodiment, a traveling system power transmission mechanism10B for transmitting the power from the driving power source40B to the HST unit100B, the first driving wheel50aand the second driving wheel50b, the caster wheels60, the working machine70, and a PTO system power transmission mechanism20B for transmitting the power from the driving power source40B to the working machine70.

The driving power source40B is supported by the vehicle frame30so that the driving shaft41extends towards the front in the horizontal direction.

Preferably, as shown inFIG. 5, the driving power source40B is supported by the vehicle frame30by way of four rubber vibration isolators47arranged at the front and the back and at the left and the right, whereby the transmitting of the vibration from the driving power source40B to the vehicle frame30is prevented as much as possible.

The HST unit100B includes an attachment frame500B in place of the attachment frame500A in the HST unit100A according to the first embodiment.

Specifically, the HST unit100B includes the first hydraulic motor unit200a, the second hydraulic motor unit200b, the hydraulic pump unit300A, and an attachment frame500B for supporting the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200bso as to define a free space between the first and second driving wheels50a,50b.

The attachment frame500B supports the hydraulic pump unit300A so that the input shaft370lies along the horizontal direction in a state attached to the vehicle frame30.

Specifically, the attachment frame500B includes the first side plate550aconfiguring the first motor supporting surface510a, the second side plate550bconfiguring the second motor supporting surface510b, and a connecting plate580B extending substantially vertically along the vehicle width direction so as to connect the first and second side plates550a,550b, as shown inFIG. 6, wherein the connecting plate580B configures the pump supporting surface520.

In the present embodiment, the hydraulic pump unit300A is supported by the front surface of the connecting plate580B with the input shaft370extending rearwards through an opening formed in the connecting plate580B.

The traveling system transmission mechanism10B is configured so as to operatively connect the driving shaft41of the driving power source40B and the input shaft370of the hydraulic pump unit300A.

In the present embodiment, the traveling system transmission mechanism10B is an universal joint15having a first end coupled to the driving shaft and a second end coupled to the input shaft.

The PTO system power transmission mechanism20B is configured so as to transmit the power from another driving shaft42in the driving power source40B to the working machine70.

In other words, the PTO system power transmission mechanism20B includes a working machine driving pulley21attached to the another driving shaft42, a change-of-direction pulley26attached to an intermediate shaft25supported by the vehicle frame so as to lie in the vehicle width direction, a working machine driven pulley22attached to the input shaft of the working machine70, and a working machine belt23wound around the working machine driving pulley21, the change-of-direction pulley26and the working machine driven pulley22.

As shown inFIG. 6, the connecting plate580B preferably has a gate shape when seen from the front in a state where the attachment frame500B is attached to the vehicle frame30, so that the free space is provided as much as possible between the first and second driving wheels50a,50b.

The working machine belt23is arranged in the free space in the present embodiment.

The effects similar to the first embodiment are also obtained in the HST unit100B.

Third Embodiment

The third embodiment of the HST unit according to the present invention will now be described with reference to the accompanied drawings.

FIG. 7andFIG. 8are a side view and a partial rear view, respectively, of a working vehicle1C to which the HST unit100C according to the present embodiment is applied.

In the figure, the same reference characters are denoted for the members that are the same as those in the first and second embodiments, and thus the explanation thereof is omitted.

The HST unit100C according to the present embodiment is configured so as to be applied to the working vehicle1C including a horizontal crank shaft type driving power source40B, similar to the second embodiment.

Specifically, the working vehicle1C includes the vehicle frame30, the driving power source40bsupported by the vehicle frame30, the HST unit100C according to the present embodiment, the traveling system power transmission mechanism10B, the first driving wheel50aand the second driving wheel50b, the caster wheels60, the working machine70, a PTO system traveling power transmission mechanism20C for transmitting power from the driving power source40B to the working machine70, and the duct80.

The PTO system transmission mechanism20C includes the working machine driving pulley21attached to the driving shaft41, an intermediate shaft27arranged parallel to the driving shaft41and below the driving shaft41, a working machine intermediate pulley28attached to the intermediate shaft27, the working machine belt23wound around the working machine driving pulley21and the working machine intermediate pulley28, a transmission shaft29with universal joints having one end coupled to the input shaft of the working machine70, and a PTO clutch device600interposed between the intermediate shaft27and the transmission shaft29, the PTO clutch device600selectively engaging or disengaging the power transmission from the intermediate shaft27to the transmission shaft29.

The HST unit100C includes an attachment frame500C in place of the attachment frame500B in the HST unit100B according to the second embodiment.

Specifically, the HST unit100C includes the first hydraulic motor unit200a, the second hydraulic motor unit200b, the hydraulic pump unit300A, and an attachment frame500C for supporting the hydraulic pump unit300A, the first hydraulic motor unit200aand the second hydraulic motor unit200bso as to define a free space between the first and second driving wheels50a,50b.

The attachment frame500C is configured so as to support the PTO clutch device600interposed in the PTO system transmission path from the driving power source40B to the working machine70, in addition to the first and second hydraulic motor units200a,200band the hydraulic pump unit300A.

In other words, the attachment frame500C includes another supporting surface530integrally extending downward from the pump supporting surface520in a state attached to the vehicle frame30, the another supporting surface530supporting the PTO clutch device600.

Specifically, the attachment frame500C includes the first side plate550aconfiguring the first motor supporting surface510a, the second side plate550bconfiguring the second motor supporting surface510b, and a connecting plate580C extending substantially vertically along the vehicle width direction so as to connect the first and second side plates550a,550b.

The connecting plate580C has the upper region forming the pump supporting surface520, and the lower region forming the another supporting surface530.

In the present embodiment, the hydraulic pump unit300A is supported by the front surface of the connecting plate580C, and the PTO clutch device600is supported by the rear surface of the connecting plate580C.

As shown inFIG. 8, the connecting plate580C is so configured to have a gate shape when seen from the front, whereby a free space is secured between the first and second driving wheels50a,50b.

The duct80is arranged in the free space in the present embodiment.

The effects similar to the first and second embodiments are also obtained in the HST unit100C.

A hydraulic pump unit in which both the first and second hydraulic pump main bodies310a,310bare accommodated in a single pump case330A has been explained by way of example in each of the above embodiment, but the present invention is not limited thereto.

In other words, a pair of first and second hydraulic pump units that are supported independently of each other by the attachment frame may be employed as the hydraulic pump unit.

In such embodiment, the first and second hydraulic pump units are fluidly connected to the first and second hydraulic motor units, respectively.

Fourth Embodiment

The fourth embodiment of the HST unit according to the present invention will now be described with reference to the accompanied drawings.

FIG. 9andFIG. 10are a side view and a partial rear view, respectively, of a working vehicle1D to which the HST unit100D according to the present embodiment is applied.

In the figure, the same reference characters are denoted for the members that are the same as those in the first to the third embodiments, and thus the explanation thereof is omitted.

The HST unit100D according to the present embodiment configures the traveling hydrostatic transmission of a working vehicle1D including the horizontal crank shaft type driving power source40B, and also configures a part of the PTO system transmission path from the driving power source40B to the working machine70.

Specifically, the working vehicle1D includes the vehicle frame30, the driving power source40B supported by the vehicle frame30, the HST unit100D according to the present embodiment, the traveling system power transmission mechanism10B for transmitting the power from the driving power source40B to the HST unit100D, the first driving wheel50aand the second driving wheel50b, the caster wheels60, the working machine70, a PTO system power transmission mechanism20D for transmitting the power from the HST unit100D to the working machine70, and the duct80.

The HST unit100D includes the first hydraulic motor unit200a, the second hydraulic motor unit200b, a hydraulic pump unit300D operatively connected to the driving power source40B, the hydraulic pump unit300D being fluidly connected to the first and second hydraulic motor units200a,200band outputting the rotational power towards the working machine70, and the attachment frame500B.

FIG. 11shows a vertical sectional rear view of the hydraulic pump unit300D.

As shown inFIG. 11toFIG. 13, the hydraulic pump unit300D includes the input shaft370operatively connected to the driving power source40B, the first and second pump shafts320a,320b, a traveling transmission mechanism380D for transmitting the power from the input shaft370to the first and second pump shafts320a,320b, the first and second hydraulic pump main bodies310a,310bsupported in a relatively non-rotatable manner at the first and second pump shafts320a,320b, respectively, a PTO shaft700for externally outputting the rotational power, a PTO transmission mechanism710for transmitting the power from the input shaft370to the PTO shaft700, and a pump case330D for accommodating the first and second hydraulic pump main bodies310a,310band for supporting the input shaft370, the first pump shaft320a, the second pump shaft320band the PTO shaft700in a rotatable manner about the respective axis line.

Similar to the first embodiment, the hydraulic pump unit300D is of a variable displacement type in the present embodiment.

Therefore, the hydraulic pump unit300D includes first and second capacity adjusting mechanisms450a,450b, in addition to the above configuration.

The first and second capacity adjusting mechanisms450a,450binclude output adjusting members460such as movable swash plates for changing the supply/suction amount of the corresponding hydraulic pump main body, and control shafts470for tilting the output adjusting member460based on external operation, as shown inFIG. 12.

As shown inFIG. 12andFIG. 13, the pump case330D includes a pump case main body340D, first and second pump-side port blocks350Da,350Db detachably coupled to the pump case main body340D, and a lid member360D detachably coupled to the pump case main body340D.

The pump case main body340D has a first end wall341D extending in a direction orthogonal to the axis line of the pump shafts320a,320b, a second end wall343D spaced apart from the first end wall341D in the axis line direction of the pump shafts320a,320b, the second end wall343D extending in a direction orthogonal to the axis line of the pump shafts320a,320b, and a peripheral wall342D for connecting the peripheral edges of the first end wall341D and the second end wall343D.

First and second openings through which the first and second hydraulic pump main bodies310a,310bare inserted, respectively, are formed in the second end wall343D.

Each control shaft470of the first and second capacity adjusting mechanism450a,450bis supported by the peripheral wall342D in a rotatable manner about the respective axis line in a state of being operable from outsides.

The first and second pump-side port blocks350Da,350Db are detachably coupled to the pump case main body340D so as to close the first and second openings, respectively.

A pair of first hydraulic pump-side operational fluid passages355aare formed in the first pump-side port block350Da.

Similarly, a pair of second hydraulic pump-side operational fluid passages355bare formed in the second pump-side port block350Db.

The pair of first and second pump-side port blocks350Da,350Db are provided in the present embodiment, as mentioned above, but a single pump-side port block may obviously be provided.

The lid member360D is coupled to the pump case main body340D so as to define a transmission mechanism accommodating space for accommodating the transmission mechanism380D in cooperation with the first end wall341D.

The input shaft370is supported by the pump case330D so that one end forming the input end extends outward.

In the present embodiment, the input shaft370is supported by the lid member360D and the second end wall343D, and one end forming the input end is extended outward from the lid member360D.

The first and second pump shafts320a,320bare supported by the lid member360D, the first end wall341D and the corresponding pump-side port blocks350Da,350Db so as to support the corresponding hydraulic pump main bodies310a,310bin the pump accommodating space.

The traveling transmission mechanism380D is configured to transmit the power from the input shaft370to the first and second pump shafts320a,320bwithin the pump case330D.

In the present embodiment, the traveling transmission mechanism380D includes a driving gear381D supported in a relatively non-rotatable manner at the input shaft370, and first and second driven gears382Da,382Db supported in a relatively non-rotatable manner at the first and second pump shafts320a,320b, respectively, so as to be engaged with the driving gear381D.

In the present embodiment, the PTO shaft700includes a first PTO shaft701for outputting the rotational power towards the front side from the pump case330D, and a second PTO shaft702for outputting the rotational power towards the rear side from the pump case330D.

The first PTO shaft701is operatively connected to the input shaft of the working machine70by way of the PTO system power transmission mechanism20D (transmission shaft29with universal joints in the present embodiment).

The second PTO shaft702is operatively connected to another working machine (not shown) arranged at the rear of the vehicle frame by way of an appropriate transmission mechanism.

The PTO transmission mechanism710is configured so as to transmit the power from the input shaft370to the first and second PTO shafts701,702within the pump case330D.

In the present embodiment, the PTO transmission mechanism710is configured so as to selectively engage or disengage the power transmission from the input shaft370to the first and second PTO shafts701,702.

Specifically, the PTO transmission mechanism710includes a PTO hydraulic clutch device720, as shown inFIG. 12andFIG. 13.

The PTO hydraulic clutch device720includes a driving-side member721operatively connected to the input shaft370and a driven-side member722operatively connected to the first and second PTO shafts701,702, and is configured so as to selectively engage or disengage the power transmission from the driving-side member721to the driven-side member722by the act of hydraulic pressure.

For example, the hydraulic pressure from the first charge pump unit400ato be hereinafter described may be used as the operational fluid for the PTO hydraulic clutch device720.

In the present embodiment, the PTO hydraulic clutch device720includes a driving-side member721supported in a relatively non-rotatable manner at the input shaft370, a driven-side member722supported in a relatively non-rotatable manner at the input shaft370, a friction plate group723including driving side friction plates supported in a relatively non-rotatable manner at the driving-side member721and driven side friction plates supported in a relatively non-rotatable manner at the driven-side member722, and a piston member724for switching the friction engagement of the friction plate group723by the act of the hydraulic pressure, as shown inFIG. 12andFIG. 13.

In the present embodiment, the PTO hydraulic clutch device720is of a hydraulic pressure operating type in which the friction plate group723is frictionally engaged when the operational fluid is being supplied.

Reference character725in the figure denotes a spring member for biasing the piston member724in a direction away from the friction plate group723, and is provided to prevent or reduce the friction produced at the friction plate group723when the operational fluid is not being supplied.

The PTO transmission mechanism710preferably includes a PTO brake device730that prevents the first and second PTO shafts701,702from continuously rotating due to the force of inertia when the PTO hydraulic clutch device720disengages the power transmission.

In the present embodiment, the PTO brake device730is of a spring operation type that applies a braking force to the driven-side member722by a biasing force of the spring, and is configured to release the braking force by the operational fluid when the operational fluid is supplied to the PTO hydraulic clutch device720.

Further, in the present embodiment, the PTO transmission mechanism710includes a PTO switching device750interposed between the PTO hydraulic PTO device720and the first and second PTO shafts701,702.

The PTO switching device750includes a counter shaft751operatively connected to the driven-side member722of the PTO hydraulic clutch device720; a first counter gear752supported in a relatively rotatable manner at the counter shaft751, the first counter gear752being operatively connected to the first PTO shaft701; a second counter gear753supported in a relatively rotatable manner at the counter shaft751, the second counter gear753being operatively connected to the second PTO shaft702; and a shifting device760for transmitting the rotation of the counter shaft751to the first counter gear751and/or the second counter gear753.

The PTO switching device750takes a state of outputting the rotational power only from the first PTO shaft701, a state of outputting the rotational power only from the second PTO shaft702, and a state of outputting the rotational power from both the first and second PTO shafts701,702, based on the operation of the shifting device760.

As shown inFIG. 12, the hydraulic pump unit300D further includes first and second charge pump units400a,400brotationally driven by the first and second pump shafts320a,320b, respectively.

The first and second charge pump units400a,400bare each arranged to replenish the operational fluid to the corresponding hydraulic pump main bodies310a,310b.

In the present embodiment, the first charge pump unit400aalso supplies the operational fluid to the PTO hydraulic clutch device720and the PTO brake device730.

The hydraulic pump unit300D includes an auxiliary pump unit800rotationally driven by at least one of first or the second pump shaft320a,320b(second pump shaft320bin the embodiment shown), as shown inFIG. 12.

For example, the auxiliary pump unit800is a high-pressure gear pump as shown inFIG. 12, and used as a hydraulic pressure source for lifting up and down the working machine.

The power transmission from the driving power source40B to the working machine70is carried out through the PTO shaft701of the hydraulic pump unit300D in the working vehicle1D.

Therefore, the hydraulic pump unit300D is supported by the attachment frame500B so that the input shaft370is positioned in the pump supporting surface520, and the first and second PTO shafts701,702are positioned within the free space defined by the connecting plate580B, when seen from the front.

The hydraulic pump unit in which both the first and second hydraulic pump main bodies310a,310bare accommodated in the single pump case330D has been explained by way of example in the present embodiment, but the present invention is not limited thereto.

In other words, a pair of first and second hydraulic pump units that are supported independently of each other by the attachment frame may be provided as the hydraulic pump unit.

In such an embodiment, the first and second hydraulic pump units are fluidly connected to the first and second hydraulic motor units, respectively, and the PTO shaft capable of outputting the rotational power from the input shaft is provided in at least one of the first or the second hydraulic pump unit.

Fifth Embodiment

The fifth embodiment of the HST unit according to the present invention will now be described with reference to the accompanying drawings.

FIG. 14is a side view of a working vehicle1E to which the HST unit100E according to the present embodiment is applied.

FIG. 15andFIG. 16are a vertical sectional front view of the HST unit100E taken along line XV-XV inFIG. 14and a horizontal sectional plane view of the HST unit100E taken along line XVI-XVI inFIG. 15.

In the figure, the same reference characters are denoted for the members that are the same as those in the first to the fourth embodiments, and thus the explanation thereof is omitted.

The HST unit100E according to the present embodiment configures the traveling hydrostatic transmission of a working vehicle1E, and also configures a part of the PTO system transmission path from the driving power source40B to the working machine70, similar to the fourth embodiment.

Specifically, the working vehicle1E includes the vehicle frame30, the driving power source40B supported by the vehicle frame30, the HST unit100E according to the present embodiment, a traveling system power transmission mechanism10E for transmitting the power from the driving power source40B to the HST unit100E, the first driving wheel50aand the second driving wheel50b, the caster wheels60, the working machine70, the PTO system power transmission mechanism20D for transmitting the power from the HST unit100E to the working machine70, and the duct80.

The HST unit100E includes the first hydraulic motor unit200a; the second hydraulic motor unit200b; a hydraulic pump unit300E operatively connected to the driving power source40B, the hydraulic pump unit300E being fluidly connected to the first and second hydraulic motor units200a,200band outputting the rotational power towards the working machine70; and an attachment frame500E attachable to the vehicle frame30in a state of supporting the first and second hydraulic motor units200a,200band the hydraulic pump unit300E.

The hydraulic pump unit300E is configured to rotatably drive the first and second hydraulic pump main bodies310a,310bby the power from the driving power source40B and to externally output the power from the driving power source40B from the PTO shaft700, similar to the hydraulic pump unit300D in the fourth embodiment.

In other words, the hydraulic pump unit300E includes the input shaft370operatively connected to the driving power source40B, the first and second pump shafts320a,320b, a traveling transmission mechanism for transmitting the power from the input shaft370to the first and second pump shafts320a,320b, the first and second hydraulic pump main bodies supported in a relatively non-rotatable manner at the first and second pump shafts320a,320b, respectively, the PTO shaft700for externally outputting the rotational power, a PTO transmission mechanism for transmitting the power from the input shaft370to the PTO shaft700, and a pump case for accommodating the first hydraulic pump main body, the second hydraulic pump main body, the traveling transmission mechanism and the PTO transmission mechanism, and for supporting the input shaft370, the first pump shaft320a, the second pump shaft320b, and the PTO shaft700in a rotatable manner about respective axis line.

In the present embodiment, the hydraulic pump unit300E further includes at least one charge pump unit400and at least one cooling fan430.

The charge pump unit400is rotationally driven by the first or second pump shaft320a,320b.

Similarly, the cooling fan430is rotationally driven by the first or second pump shaft320a,320b.

In the illustrated embodiment, the charge pump unit400is rotationally driven by the first pump shaft320a, and the cooling fan430is rotationally driven by the second pump shaft320b.

The PTO transmission mechanism includes a PTO hydraulic clutch device720(seeFIG. 14) for selectively engaging or disengaging the power transmission from the input shaft370to the PTO shaft700, similar to the fourth embodiment.

The PTO transmission mechanism preferably includes the PTO brake device that prevents the PTO shaft700from continuously rotating due to the force of inertia when the PTO hydraulic clutch device disengages the power transmission, similar to the fourth embodiment.

The attachment frame500E includes the first side plate550aconfiguring the first motor supporting surface510a, the second side plate550bconfiguring the second motor supporting surface510b, a first connecting plate581E extending in the vehicle width direction lying substantially vertically so as to connect one side (front side) in the front and back direction of the vehicle of the first and second side plates550a,550b, a second connecting plate582E extending in the vehicle width direction lying substantially vertically so as to connect the other side (back side) in the front and back direction of the vehicle of the first and second side plates550a,550b, and a top plate560E lying substantially horizontally so as to connect the upper ends of the first and second side plates550a,550bas well as the first and second connecting plates581E,582E, as shown inFIG. 14toFIG. 16.

The attachment frame500E supports the hydraulic pump unit300E within a space surrounded by the first side plate550a, the second side plate550b, the first connecting plate581E, the second connecting plate582E, and the top plate560E.

In the present embodiment, the inner surface of the second connecting plate582E facing the first connecting plate581E is the pump supporting surface520for supporting the hydraulic pump unit300E, as shown inFIG. 14toFIG. 16.

Specifically, an opening through which the input shaft370is inserted is formed in the second connecting plate582E.

The second connecting plate582E supports the hydraulic pump unit300E at the inner surface so that the input shaft370projects in the horizontal direction and outward in a direction approaching the driving power source40B from the space through the opening.

As shown inFIG. 14toFIG. 16, the openings585a,585bthrough which the link mechanisms37a,37bare inserted, respectively, and the opening586through which the transmission shaft29is inserted are formed in the first connecting plate581E.

In the present embodiment, the input shaft370has the rotational axis line thereof directed in the front and back direction of the vehicle similar to the driving shaft41in the driving power source40b, but the axis line of the input shaft370is off set in the vehicle width direction with respect to the driving shaft41.

Therefore, the traveling system power transmission mechanism10A is a pulley-belt transmission mechanism including the travel driving pulley11, the travel driven pulley12, and the travel belt13.

Further, the hydraulic pump unit in which both the first and second hydraulic pump main bodies310a,310bare accommodated in the single pump case is given by way of example in the present embodiment, but the present invention is not limited thereto.

In other words, a pair of first and second hydraulic pump units that are supported independently of each other by the attachment frame may be provided as the hydraulic pump unit.

In such an embodiment, the first and second hydraulic pump units are fluidly connected to the first and second hydraulic motor units, respectively, and the PTO shaft capable of outputting the rotational power from the input shaft is provided in at least one of the first or the second hydraulic pump unit.

In each embodiment, an example in which the first and second hydraulic pump main bodies310a,310bare independently fluidly connected to the first and second hydraulic motor main bodies210a,210b, respectively, is given by way of example, but the present invention is not limited thereto.

In other words, the first and second hydraulic motor main bodies210a,210bmay be fluidly connected by a pair of motor-side conduits, and the pair of motor-side conduits and a single traveling hydraulic pump main body may be fluidly connected.

For instance, one of the first or the second hydraulic pump main body310a,310bin each embodiment may be used as the traveling hydraulic pump main body.

In this case, the other one of the first or the second hydraulic pump main body310a,310bmay be omitted, or the other one of the first or the second hydraulic pump main body310a,310bmay be used as a hydraulic pressure source for other hydraulic equipments.

Sixth Embodiment

The sixth embodiment of the HST unit according to the present invention will now be described with reference to the accompanied drawings.

FIGS. 17 to 19are a side view, a partial rear view and a hydraulic circuit diagram, respectively, of a working vehicle1F to which the HST unit100F according to the present embodiment is applied.

As shown inFIGS. 17 to 19, the working vehicle1F includes a vehicle frame30, the HST unit100F configuring the traveling hydrostatic transmission, a driving power source40F of a vertical crank shaft type that act as a power source for the hydraulic pump unit100F, a traveling system power transmission mechanism10F for transmitting the power from the driving power source40F to the HST unit100F, the pair of first driving wheel50aand second driving wheel50b(rear wheels in the present embodiment), and the caster wheels60(front wheels in the present embodiment).

In the present embodiment, the working vehicle1F is of a rear discharge type riding lawn mower.

That is, the working vehicle1F further includes a driver's seat35, a working machine70(mower device in the present embodiment) suspended and supported between the driving wheels50and the caster wheels60in a state capable of lifting upwardly and downwardly, a PTO system power transmission mechanism20F for transmitting the power from the driving power source40A to the working machine70, and a duct80for guiding the grass cut by the working machine70to a grass collecting bag (not shown) arranged at the back of the vehicle body.

The HST unit100F is configured so as to form the traveling hydrostatic transmission while providing a free space between the pair of driving wheels50a,50b.

Specifically, as shown inFIGS. 17 and 18, the HST unit100F includes; a first hydraulic motor unit200afor operatively driving the first driving wheel50a; a second hydraulic motor unit200bfor operatively driving the second driving wheel50b; a hydraulic pump unit300F operatively connected to the driving source40F, the hydraulic pump unit300F being fluidly connected to the first and second hydraulic motor units200a,200b; and an attachment frame500F for supporting the driving power source40F, the hydraulic pump unit300F, the first hydraulic motor unit200aand the second hydraulic motor unit200bso as to define a free space between the first and second driving wheels50a50b.

At least one of the hydraulic pump unit300F, and the first and second hydraulic motor units200a,200bis (are) of a variable displacement type.

In the present embodiment, the hydraulic pump unit300F is of the variable displacement type, and the first and second hydraulic motor units200a,200bare of the fixed displacement type.

FIG. 20shows a vertical sectional rear view in the vicinity of the first hydraulic motor unit200a.

The second hydraulic motor unit200bhas substantially the same configuration as that of the first hydraulic motor unit200a.

Therefore, the corresponding members of the second hydraulic motor unit200bare designated by the same reference numerals or the same reference numerals with replacing subscript with b as those of the first hydraulic motor unit200a, and thus the detailed description thereof is omitted.

As shown inFIG. 20, the first hydraulic motor unit200ais configured so as to operatively drive the corresponding first driving wheel50a.

Specifically, the first hydraulic motor unit200aincludes a first hydraulic motor main body210a, a first motor shaft220arotationally driven about the axis line by the first hydraulic motor main body210a, and a first motor case230afor accommodating the first hydraulic motor main body210aand for supporting the first motor shaft220ain a rotatable manner about the axis line.

The first motor case230aincludes a motor case main body240ahaving an opening, through which the first hydraulic motor main body210acan be inserted, formed on the first end face (end face facing inward in the vehicle width direction in a state mounted to the vehicle frame30in the present embodiment), and a first motor-side port block250a(first motor-side center section) coupled to the motor case main body240aso as to close the opening.

As shown inFIGS. 19 and 20, the motor case main body240ais provided with a first motor-side drain port245a(P) for taking out the oil stored within the inner space of the first motor case230ato the outsides.

The first motor-side port block250ais provided with a pair of first hydraulic motor-side operational fluid passages255ahaving first ends fluidly connected to the first hydraulic motor main body210aand second ends opened to the outer surface.

The second ends of the pair of first hydraulic motor-side operational fluid passages255aform first hydraulic motor-side operational fluid ports255a(P) which act as fluid connecting ports to the first hydraulic pump main body310a, to be hereinafter described.

The first motor shaft220ahas a first end operatively connected to a driving axle51for the first driving wheel50a.

Preferably, the first motor shaft220ais operatively connected to the corresponding driving axle51via a reduction transmission mechanism55, as shown inFIGS. 19 and 20.

With the reduction transmission mechanism55, capacity of the first hydraulic motor main body210acould be made smaller.

In the present embodiment, the first hydraulic motor unit200ahas, in addition to the above configuration, a brake mechanism270that selectively applies a braking force to the first motor shaft220a.

Specifically, the first motor shaft220ahas a second end (end opposite the first end operatively connected to the first driving wheel50a) extending outward from the first motor-side port block250a.

The brake mechanism270is configured so as to selectively apply the braking force to the second end of the first motor shaft220based on external operation.

The brake mechanism270is of an internal expanding type in the present embodiment.

Specifically, the brake mechanism270includes a brake drum271supported in a relatively non-rotatable manner at the second end of the first motor shaft220a, a brake shoe272arranged facing the inner peripheral surface of the brake drum271, a biasing member273for biasing the brake shoe272in a direction away from the inner peripheral surface of the brake drum271, and a brake operation arm274for pushing the brake shoe272toward the inner peripheral surface of the brake drum271against the biasing force of the biasing member273.

Although the inner expanding brake device is adopted as the brake mechanism270in the present embodiment, other brake devices such as a disc brake device could obviously be used.

FIG. 21shows a plane view of the HST unit100F, andFIG. 22shows a vertical sectional front view of the hydraulic pump unit300F taken along line XXII-XXII inFIG. 17.

As shown inFIGS. 21 and 22, in the present embodiment, the hydraulic pump unit300F includes a first hydraulic pump main body310aand a second hydraulic pump main body310bthat are fluidly connected to the first hydraulic motor main body210aand the second hydraulic motor main body, respectively, and is so configured that the first and second hydraulic pump main bodies310a,310bare accommodated in a single pump case330F.

Specifically, the hydraulic pump unit300F includes an input shaft370operatively connected to the driving power source40F, the first and second pump shafts320a,320b, a transmission mechanism380for transmitting the power from the input shaft370to the first and second pump shafts320a,320b, the first and second hydraulic pump main bodies310a,310bthat are supported in a relatively non-rotatable manner at the first and second pump shafts320a,320b, respectively, and a pump case330F for accommodating the first and second hydraulic pump main bodies310a,310band for supporting the input shaft370, and the first and second pump shafts320a,320bin a rotatable manner about the respective axis line.

In the present embodiment, the hydraulic pump unit300F is of a variable displacement type, as mentioned above.

Therefore, the hydraulic pump unit includes first and second capacity adjusting mechanisms450a,450bfor respectively changing the supply/suction amount of the first and second hydraulic pump main bodies310a,310bbased on external operation, in addition to the above configuration.

The first and second capacity adjusting mechanisms450a,450beach includes an output adjusting member460(seeFIG. 22) such as a movable swash plate for changing the supply/suction amount of the corresponding hydraulic pump main body310, and a control shaft470(seeFIGS. 17 and 21) for tilting the output adjusting member460based on external operation.

Each control shaft470of the first and second capacity adjusting mechanisms450a,450bis operatively connected to a pair of steering levers36a,36b, respectively, arranged at the front of the driver's seat35by way of appropriate link mechanisms37a,37b(seeFIG. 17).

The pump case330F includes a pump case main body340F, a pump-side port block350F (pump-side center section) detachably coupled to the pump case main body340F, and a lid member360F detachably coupled to the pump case main body340F.

As shown inFIG. 22, the pump case main body340F has an end wall341F that extends in a direction substantially orthogonal to the axis line direction of the pump shafts320a,320b, and a peripheral wall342F extending in the axis line direction of the pump shafts320a,320bfrom the peripheral edge of the end wall341F.

The peripheral wall342F has an opening at a free end side opposite the end wall341F.

The opening is sized to allow the first and second hydraulic pump main bodies310a,310bto be inserted.

The pump-side port block350F is coupled to the pump case main body340F so as to close the opening.

In other words, a pump accommodating space for accommodating the first and second hydraulic pump main bodies310a,310bis defined by the end wall341F and the peripheral wall342F of the pump case main body340F, and the pump-side port block350F.

The pump case main body340F is provided with a pump-side drain port345(P) for taking out the oil stored within the pump accommodating space to the outsides.

As shown inFIGS. 19 and 22, the pump-side port block350F is provided with a pair of first hydraulic pump-side operational fluid passages355ahaving first ends fluidly connected to the first hydraulic pump main body310aand second ends opened to the outer surface, and a pair of second hydraulic pump-side operational fluid passages355bhaving first ends fluidly connected to the second hydraulic pump main body310band second ends opened to the outer surface.

The second ends of the pair of first hydraulic pump-side operational fluid passages355aform first hydraulic pump-side operational fluid ports355a(P) which act as the fluid connecting ports to the first hydraulic motor main body210a(seeFIGS. 18 and 19).

The second ends of the pair of second hydraulic pump-side operational fluid passages355bform second hydraulic pump-side operational fluid ports355b(P) which act as the fluid connecting ports to the second hydraulic motor main body (seeFIGS. 18 and 19).

As shown inFIG. 19, the pump-side port block350F is further provided with a charge passage356having a first end opened to the outer surface so as to form a charge port (not shown) and second ends fluidly connected to each of the pair of first hydraulic pump-side operational fluid passages355aand each of the pair of second hydraulic pump-side operational fluid passages355bvia check valves357, respectively.

Furthermore, the pump-side port block350F is provided with a first bypass passage358acommunicating between the pair of first hydraulic pump-side operational fluid passages355a, and a second bypass passage358bcommunicating between the pair of second hydraulic pump-side operational fluid passages355b(seeFIG. 19).

In each of the first and second bypass passages358a,358b, a bypass valve with relief function359is interposed.

The lid member360FA is coupled to the pump case main body340F so as to define a transmission mechanism accommodating space for accommodating the transmission mechanism380in cooperation with the end wall341F.

The input shaft370is supported by the pump case330F so that one end forming the input end extends outward.

The first and second pump shafts320a,320bare supported at the both ends by the lid member360F and the pump-side port block350F so as to support the corresponding hydraulic pump main bodies310a,310bwithin the pump accommodating space.

The transmission mechanism380is configured to transmit the power from the input shaft370to the first and second pump shafts320a,320b.

In the present embodiment, the first pump shaft320aand the input shaft370are integrally formed by a single shaft325, as shown inFIGS. 18 and 22.

Therefore, the transmission mechanism380includes a driving gear381supported in a relatively non-rotatable manner at the single shaft325, and a driven gear382supported in a relatively non-rotatable manner at the second pump shaft320bso as to engage with the driving gear381.

Preferably, one of or both of the first and second pump shafts320a,320bhas (have) at least one end extending outward from the pump case330F.

The projecting end is used as the driving shaft for the charge pump main body annexed to the hydraulic pump unit300aor other rotating members, as desired.

In the present embodiment, the input shaft370and the first pump shaft320aare integrally formed by the single shaft325, as explained above.

As shown inFIG. 22, the single shaft325has a first end passing through the lid member360F and projecting outward to form the input end, and a second end passing through the pump-side port block350F and extending outward.

The second end of the single shaft325acts as the driving shaft for a charge pump main body410that is to be hereinafter described.

In the present embodiment, the second pump shaft320balso has a second end passing through the pump-side port block350F and extending outward, at which a cooling fun430is supported in a relatively non-rotatable manner, as shown inFIG. 22.

In the present embodiment, the hydraulic pump unit300F includes a charge pump unit400, in addition to the above configuration.

The charge pump unit includes a charge pump main body410operatively driven by the rotational power of the input shaft370, and a charge pump case420surrounding the charge pump main body410, as shown inFIG. 22.

In the present embodiment, the charge pump main body410is configured so as to be driven by the second end of the single shaft325.

The charge pump case420is coupled to the pump-side port block350F so as to surround the charge pump main body410.

As shown inFIG. 19, the charge pump case420is provided with a suction passage425having a first end opened to the outer surface so as to form a suction port425(P) and a second end fluidly connected to a suction side of the charge pump main body410, and a discharge passage426having a first end fluidly connected to a discharge side of the charge pump main body410and a second end opened to a contact surface with the pump-side port block350F so as to be fluidly connected to the charge passage356.

Furthermore, the charge pump case420or the pump-side port block350F is provided with a charge pressure setting passage421having a first end fluidly connected to the charge passage356and a second end fluidly connected to an oil tank (the pump accommodating space in the present embodiment), a relief valve422interposed in the charge pressure setting passage421, and a check valve for self-suction423interposed in the charge pressure setting passage421in parallel with the relief valve422.

The attachment frame500F is so configured to support the driving power source40F, the hydraulic pump unit300F, the first hydraulic motor unit200aand the second hydraulic motor unit200b, and to be attachable to the vehicle frame30while providing a free space between the first and second driving wheels50a,50b.

Specifically, the attachment frame500F integrally includes a first side plate550aarranged on one side in the vehicle width direction so as to be positioned in the vicinity of the first driving wheel50a, a second side plate550barranged on the other side in the vehicle width direction so as to be positioned in the vicinity of the second driving wheel50b, and a top plate560F extending in the vehicle width direction in a state of being substantially horizontally between the first and second side plates550a,550b, in a state attached to the vehicle frame30, as shown inFIGS. 18 and 21.

The first side plate550aextends substantially vertically so as to face the first driving wheel50a, and form a first motor supporting surface510afor supporting the first hydraulic motor unit200a.

Similarly, the second side plate550bextends substantially vertically so as to face the second driving wheel50b, and form a second motor supporting surface510bfor supporting the second hydraulic motor unit200b.

The top plate560F is positioned above the first and second motor supporting surfaces510a,510b, and support the driving power source40F and the hydraulic pump unit300F so that the driving shaft41and the input shaft370extends substantially vertically.

Specifically, the top plate560F is provided with an opening561through which the driving shaft41of the driving power source40can pass (seeFIG. 21), and an opening562through which the input shaft370can pass.

The top plate560F supports the driving power source40F and the hydraulic pump unit300F at its upper surface in a state where the end portions of the driving shaft41and the input end of the input shaft370are positioned below the top plate560F through the openings561,562.

Preferably, the driving power source40F is supported by the attachment frame500F via elastic members46. With the configuration, vibration from the driving power source40F could be effectively prevented from transmitting to the vehicle frame30via the attachment frame500F.

In order to simplify the connecting structure between the driving shaft41and the input shaft370that are extend substantially vertically, in the present embodiment, a pulley/belt mechanism is employed as the traveling system power transmission mechanism10F.

Specifically, as shown inFIGS. 17,18,21and22, the traveling system power transmission mechanism10F includes a travel driving pulley11attached to the driving shaft41of the driving power source40F so as to be positioned below the top plate560F, a travel driven pulley12attached to the input shaft370of the hydraulic pump unit300F so as to be positioned below the top plate560F, and a travel belt13wound around the travel driving pulley11and the travel driven pulley12.

Similarly, the PTO system power transmission mechanism20F is also a pulley/belt mechanism.

As shown inFIG. 17, the PTO system power transmission mechanism20F includes a working machine driving pulley21attached to the driving shaft41of the driving power source40F so as to be positioned below the top plate560F, a working machine driven pulley22attached to the input shaft of the working machine70, and a working machine belt23wound around the working machine driving pulley21and the working machine driven pulley22.

In the HST unit100F having the thus constructed attachment frame500F, by attaching the hydraulic pump unit300F, the first hydraulic motor unit200aand the second hydraulic motor unit200bthat configures the traveling hydrostatic transmission, and the driving power source40F that are the power source for the traveling hydrostatic transmission to the attachment frame500F in advance, and then attaching the attachment frame500F to the vehicle frame30, it is possible to complete the attachment work of the driving power source40F, the hydraulic pump unit300F and the first and second hydraulic motor units200a,200bto the vehicle frame30while providing the free space between the first and second driving wheels50a,50b.

Therefore, the efficiency of the assembly work of the vehicle could be enhanced.

In this embodiment, as shown inFIGS. 17,18and the like, the attachment frame500F integrally includes a first connecting plate570F extending in the vehicle width direction in a state of lying substantially vertically so as to connect edges on one side (front edge in this embodiment) in the front and back direction of the vehicle of the first side plate550aand the second side plate550b, and an edge on one side in the front and back direction of the vehicle of the top plate560F, a second connecting plate575F extending in the vehicle width direction in a state of lying substantially vertically so as to connect edges on the other side (rear edge in this embodiment) in the front and back direction of the vehicle of the first side plate550aand the second side plate550b, and a lower surface of the top plate560F, a first side extension plate580a(seeFIG. 21) extending from the edge on the other side of the first side plate550atoward the other side in the front and back direction of the vehicle in a state of lying substantially vertically and connected to the top plate560F, a second side extension plate580b(seeFIGS. 17 and 21) extending from the edge on the other side of the second side plate550btoward the other side in the front and back direction of the vehicle in a state of lying substantially vertically and connected to the top plate560F, and a third connecting plate585F (seeFIGS. 17 and 21) extending in the vehicle width direction in a state of lying substantially vertically so as to connect edges on the other side in the front and back direction of the vehicle of the first side extension plate580aand the second side extension580b, and an edge on the other side in the front and back direction of the vehicle of the top plate560F, thereby enhancing the strength of the attachment frame500F.

In a case where the first and second connecting plates570F,575F are provided, it is possible to provide the free space as much as possible by having the first and second connecting plates570F,575F gate-shaped when seen from the front.

At the second connecting plate575F, an opening576F (seeFIG. 22) through which the traveling belt13passes, and an opening (not shown) through which the working machine belt23passes are formed.

At the first connecting plate570F, an opening571F (seeFIG. 18) through which the working machine belt23passes is formed.

In the HST100F, the hydraulic pump unit300F, the first hydraulic motor unit200aand the second hydraulic motor unit200bare independently supported by the attachment frame500F. Therefore, the replacing work and the maintenance work of the hydraulic units can be easily carried out.

Furthermore, in the HST unit100F, the conduit connecting work between the first and second hydraulic pump main bodies310a,310b, and the first and second hydraulic motor main bodies210a,210bcan also be carried out without assembling the hydraulic pump unit300F as well as the first and second hydraulic motor units200a,200bto the vehicle frame30.

In other words, in the HST100F, it is possible to complete the connecting work between the first hydraulic pump main body310aand the first hydraulic motor main body210aby fluidly connecting the first hydraulic pump-side operational fluid ports355a(P) and the first hydraulic motor-side operational fluid ports255a(P) by means of the first operational fluid conduit480a; and complete the connecting work between the second hydraulic pump main body310band the second hydraulic motor main body by fluidly connecting the second hydraulic pump-side operational fluid ports355a(P) and the second hydraulic motor-side operational fluid ports255b(P) by means of the second operational fluid conduit480b, in a state where the hydraulic pump unit300F as well as the first and second hydraulic motor units200a,200bare attached only to the attachment frame500A, without attaching these units to the vehicle frame.

That is, in the HST unit100F, the conduit connecting work could be carried out irrespective of the assembly work to the vehicle frame.

The first operational fluid conduit480aand the second operational fluid conduit480bare preferably supported by the attachment frame500F, as shown inFIG. 18.

Further, the adjustment work of the traveling hydrostatic transmission configured by the hydraulic pump unit300F as well as the first and second hydraulic motor units200a,200bcould be more efficient in the HST unit100F.

Specifically, in the HST unit100F, it is possible that the first and second hydraulic pump main bodies310a,310band the first and second hydraulic motor main bodies are fluidly connected in a state corresponding to the usage state before attaching the hydraulic pump unit300F, the first hydraulic motor unit200aand the second hydraulic motor unit200bto the vehicle frame30, as explained above.

Therefore, the adjustment work of the traveling hydrostatic transmission could be carried out irrespective of the vehicle main body.

In particular, in a case where the hydraulic equipment manufacturing company manufactures the hydraulic pump unit and the hydraulic motor unit, and the vehicle manufacturing company attaches the hydraulic pump unit and the hydraulic motor unit to the vehicle frame and completes the working vehicle, the HST unit100F allows the hydraulic equipment manufacturing company to carry out the adjustment work of the hydraulic pump unit and the hydraulic motor unit in a state corresponding to the vehicle mounted state before shipment of the traveling hydrostatic transmission. Therefore, the vehicle manufacturing company could assemble the traveling hydrostatic transmission to the vehicle frame, only with an extremely simple work of attaching the attachment frame500F to the vehicle frame.

Further, the attachment frame500F is configured so that the first and second motor supporting surfaces510a,510bare positioned respectively at one side and the other side in the vehicle width direction, and the top plate560F supports the driving power source40F and the hydraulic pump unit300F above the first and second motor supporting surfaces510a,510b, as described above.

Therefore, the pair of hydraulic motor units200a,200bcan be arranged in a distributed manner in the vehicle width direction so as to provide the free space between the driving wheels50a,50bby simply attaching the attachment frame500F to the vehicle frame30.

Such effect is particularly effective in the working vehicle, for example, needing to stabilize the body posture at the time of turning in place (zero turn).

In the working vehicle1F, a PTO system power transmission mechanism20F and the duct80are arranged in the free space, as shown inFIG. 18.

Moreover, the working vehicle1F includes a reservoir tank900that is an oil source of the operational fluid in the traveling hydrostatic transmission configured by the hydraulic pump unit300F, the first hydraulic motor unit200a, and the second hydraulic motor unit200b.

Specifically, the reservoir tank900is fluidly connected with the inner space of the first motor case230avia a first motor-side conduit490ahaving a first end fluidly connected to the first motor-side drain port245a(P), the inner space of the second motor case230bvia a second motor-side conduit490bhaving a first end fluidly connected to the second motor-side drain port245b(P), and the inner space of the pump case330F via a pump-side conduit491having a first end fluidly connected to the pump-side drain port345(P).

Furthermore, the reservoir tank900is fluidly connected to the suction passage425via a charge conduit495having a first end fluidly connected to the suction port425(P).

In the present embodiment, the thus constructed reservoir tank900is also supported by the attachment frame500F.

Specifically, the top plate560F of the attachment frame500F supports the reservoir tank900at the upper surface, in addition to the driving power source40F and the hydraulic pump unit300F.

Preferably, a filter unit950is further provided so as to filer the oil introduced into the suction passage425from the reservoir tank900.

In the present embodiment, the filter unit950is separate from the reservoir tank900, as shown inFIGS. 21 and 22.

The independent filter unit950may be supported on the upper surface of the top plate560F in a state of interposed in the charge conduit495.

It is possible to provide an inner packaging type filter unit at an outlet port of the reservoir tank900, instead of the independent filter unit950.

Seventh Embodiment

The seventh embodiment of the HST unit according to the present invention will now be described with reference to the accompanied drawings.

FIG. 23andFIG. 24are a side view and a partial rear view, respectively, of a working vehicle1G to which the HST unit100G according to the present embodiment is applied.

FIG. 25is a plane view of the HST unit100G according to the present embodiment.

In the figure, the same reference characters are denoted for the members that are the same as those in the above embodiments, and thus the explanation thereof is omitted.

The HST unit100G according to the present embodiment is configured so as to be applied to the working vehicle1G including a horizontal crankshaft type driving power source40G.

Specifically, the working vehicle1G includes the vehicle frame30, the HST unit100G according to the present embodiment, the driving power source40G of a horizontal crank shaft type that act as a power source for the hydraulic pump unit100G, a traveling system power transmission mechanism10G for transmitting the power from the driving power source40G to the HST unit100G, the first and second driving wheel50a,50b, the caster wheels60, the working machine70, a PTO system power transmission mechanism20G for transmitting the power from the driving power source40G to the working machine70, the duct80, the reservoir tank900, and the filter unit950.

The HST unit100G includes an attachment frame500G in place of the attachment frame500F in the HST unit100F according to the sixth embodiment.

Specifically, the HST unit100G includes the first hydraulic motor unit200a, the second hydraulic motor unit200b, the hydraulic pump unit300F, and an attachment frame500G for supporting the driving power source40G, the hydraulic pump unit300F, the first and second hydraulic motor unit200a,200b, the reservoir tank900and the filter unit950while providing a free space between the first and second driving wheels50a,50b.

The attachment frame500G is configured so as to support the driving power source40G so that the driving shaft41extends horizontally and support the hydraulic pump unit300F so that the input shaft370extends horizontally, in a state of being attached to the vehicle frame30.

Specifically, as shown inFIGS. 23 to 25, the attachment frame500G integrally includes the first side plate550aconfiguring the first motor supporting surface510a, the second side plate550bconfiguring the second motor supporting surface510b, a top plate560G extending in the width direction and in the fore-and-aft direction of the vehicle in a state of being substantially horizontally so as to connect the first and second side plates550a,550b, and a first connecting plate570G extending in the vehicle width direction in a state of being substantially vertically so as to connect edges on one side (front edges in this embodiment) in the front and back direction of the vehicle of the first side plate550aand the second side plate550b.

The attachment frame500G is so configured that the top plate560G supports the driving power source40G and the first connecting plate570G supports the hydraulic pump unit300F.

As shown inFIG. 25, the top plate560G supports the driving power source40G so that the driving shaft41extends horizontally toward the front.

In the present embodiment, as shown inFIG. 23, the driving power source40G is supported on the upper surface of the top plate560G so that at least a part of the power source40G is positioned below the top plate560G, thereby allowing the vertical position of the driving shaft41to be adjusted.

Specifically, as shown inFIG. 25, the top plate560G is provided with a first opening561G corresponding to the driving power source40G. The driving power source40G is supported by the top plate560G by way of four rubber vibration isolators46arranged at the front and the back and at the left and the right, in a state of being within the first opening561G so that at least a part of the driving power source40G is positioned below the top plate560G.

In the present embodiment, as shown inFIGS. 23 and 25, a flywheel45is supported on the driving shaft41. The driving shaft41is operatively connected with the input shaft of the hydraulic pump unit300F via the flywheel45and a transmission shaft15with universal joints configuring the traveling system power transmission mechanism10G.

In order to prevent the flywheel45and the transmission shaft with universal joints15from interfering with the top plate560G, the top plate560G is provided with a second opening562G corresponding to the flywheel and a third opening563G corresponding to the transmission shaft with universal joints15, in addition to the first opening561G (seeFIG. 25).

As shown inFIG. 25, the reservoir tank900and the filter unit950are supported by the top plate560G at a desired position other than the first to third openings561G-563G.

The first connecting plate570G is configured to support the hydraulic pump unit300F so that the input shaft370extends horizontally toward the rear.

Specifically, the first connecting plate570G is provided with an opening through with the input shaft370passes. The first connecting plate570G supports the hydraulic pump unit300F at its front surface in a state where the input shaft370extends rearward through the opening.

Preferably, the first connecting plate570G may support the hydraulic pump unit300F so that the input shaft370is positioned coaxially with the driving shaft41.

In the present embodiment, as shown inFIG. 24, the first connecting plate570G is configured so that at least a part of the plate570G projects upwardly beyond the top plate560G. The first connecting plate570G supports the hydraulic pump unit300F by utilizing the upward projecting portion so that the vertical position of the input shaft370is set coaxially with the driving shaft41.

In this embodiment, as shown inFIGS. 23-25, the attachment frame500G integrally includes a second connecting plate575G extending in the vehicle width direction in a state of lying substantially vertically so as to connect edges on the other side (rear edges in this embodiment) in the front and back direction of the vehicle of the first side plate550aand the second side plate550b, a first side extension plate580a(seeFIG. 25) extending from the edge on the other side of the first side plate550atoward the other side in the front and back direction of the vehicle in a state of lying substantially vertically and connected to the top plate560G, a second side extension plate580b(seeFIGS. 23 and 25) extending from the edge on the other side of the second side plate550btoward the other side in the front and back direction of the vehicle in a state of lying substantially vertically and connected to the top plate560G, and a third connecting plate585F (seeFIGS. 23 and 25) extending in the vehicle width direction in a state of lying substantially vertically so as to connect edges on the other side in the front and back direction of the vehicle of the first side extension plate580aand the second side extension580b, and a edge on the other side in the front and back direction of the vehicle of the top plate560G, thereby enhancing the strength of the attachment frame500G.

The PTO system power transmission mechanism20G is so configured to operatively connect between the driving shaft41and the working machine70.

Specifically, the PTO system transmission mechanism20G includes the working machine driving pulley21attached to the transmission shaft with universal joints15, an intermediate shaft27arranged parallel to and below the transmission shaft15, a working machine intermediate pulley28attached to the intermediate shaft27, the working machine belt23wound around the working machine driving pulley21and the working machine intermediate pulley28, a transmission shaft29with universal joints having one end coupled to the input shaft of the working machine70, and a PTO clutch device600interposed between the intermediate shaft27and the transmission shaft29, the PTO clutch device600selectively engaging or disengaging the power transmission from the intermediate shaft27to the transmission shaft29.

The working machine driving pulley21and the working machine belt23are positioned within the second opening562G of the top plate560G, so as to prevent interference with the top plate560G.

The PTO clutch device600is supported by the attachment frame500G.

That is, the attachment frame500G is configured so as to support the PTO clutch device600interposed in the PTO system transmission path from the driving power source40G to the working machine70, in addition to the driving power source40G, the hydraulic pump unit300F, the first and second hydraulic motor units200a,200b, the reservoir tank900and the filter unit950.

In the present embodiment, the PTO clutch device600is supported at a region below the region for supporting the hydraulic pump unit300F, of the first connecting plate570G.

That is, the first connecting plate570G has an upper region forming a pump supporting surface for supporting the hydraulic pump unit300F, and a lower region forming another supporting surface for supporting the PTO clutch device600.

In the present embodiment, the hydraulic pump unit300F is supported by the front surface of the first connecting plate580G, and the PTO clutch device600is supported by the rear surface of the first connecting plate580G.

In the present embodiment, as shown inFIG. 24, the first and second connecting plates570G,575G have a gate shape when seen from the front, thereby providing the free space between the first and second driving wheels50a,50bas much as possible.

The duct80is arranged in the free space in the present embodiment.

The effects similar to the sixth embodiment are also obtained in the HST unit100G.

Eighth Embodiment

The eighth embodiment of the HST unit according to the present invention will now be described with reference to the accompanying drawings.

FIG. 26is a side view of a working vehicle1H to which the HST unit100H according to the present embodiment is applied.

FIG. 27andFIG. 28are a vertical sectional front view of the HST unit100H taken along line XXVII-XXVII inFIG. 26and a plane view of the HST unit100H taken along line XXVIII-XXVIII inFIG. 27.

In the figure, the same reference characters are denoted for the members that are the same as those in the above embodiments, and thus the explanation thereof is omitted.

The HST unit100H according to the present embodiment configures the traveling hydrostatic transmission of a working vehicle1H, and also configures a part of the PTO system transmission path from the driving power source to the working machine70.

In the present embodiment, the working vehicle1H includes the horizontal crankshaft type driving power source40G.

Specifically, the working vehicle1H includes the vehicle frame30, the HST unit100H according to the present embodiment, the driving power source40G of a horizontal crankshaft type that acts as a power source for the hydraulic pump unit100H, a traveling system power transmission mechanism10H for transmitting the power from the driving power source40G to the HST unit100H, the first and second driving wheel50a,50b, the caster wheels60, the working machine70, the PTO system power transmission mechanism20G for transmitting the power from the driving power source40G to the working machine70, the duct80, the reservoir tank900, and the filter unit950.

The HST unit100H includes the first hydraulic motor unit200a, the second hydraulic motor unit200b, the hydraulic pump unit300H, and an attachment frame500H for supporting the driving power source40G, the hydraulic pump unit300H, the first and second hydraulic motor unit200a,200b, the reservoir tank900and the filter unit950while providing a free space between the first and second driving wheels50a,50b.

The hydraulic pump unit300H is configured to rotatably drive the first and second hydraulic pump main bodies310a,310bthrough operational fluid by the power from the driving power source40G, and to externally output the power from the driving power source40G.

In other words, the hydraulic pump unit300H includes the input shaft370operatively connected to the driving power source40G via the traveling system transmission mechanism10H, the first and second pump shafts320a,320b, a traveling transmission mechanism (not shown), such as a gear train, for transmitting the power from the input shaft370to the first and second pump shafts320a,320b, the first and second hydraulic pump main bodies310a,310bsupported in a relatively non-rotatable manner at the first and second pump shafts320a,320b, respectively, the PTO shaft700for externally outputting the rotational power, a PTO transmission mechanism, such as a gear train, for transmitting the power from the input shaft370to the PTO shaft700, and a pump case330H for accommodating the first hydraulic pump main body310a, the second hydraulic pump main body310b, the traveling transmission mechanism and the PTO transmission mechanism, and for supporting the input shaft370, the first pump shaft320a, the second pump shaft320band the PTO shaft700in a rotatable manner about respective axis line.

The hydraulic pump unit300H further includes at least one charge pump unit400and at least one cooling fan430, as similar to the hydraulic pump unit300F.

The charge pump unit400is rotationally driven by the first or second pump shaft320a,320b.

Similarly, the cooling fan430is rotationally driven by the first or second pump shaft320a,320b.

In the illustrated embodiment, the charge pump unit400is rotationally driven by the second pump shaft320b, and the cooling fan430is rotationally driven by the first pump shaft320a.

The PTO transmission mechanism includes a PTO hydraulic clutch device720(seeFIG. 26) for selectively engaging or disengaging the power transmission from the input shaft370to the PTO shaft700.

The PTO transmission mechanism preferably includes the PTO brake device (not shown) that prevents the PTO shaft700from continuously rotating due to the force of inertia when the PTO hydraulic clutch device disengages the power transmission.

The attachment frame500H is configured so as to support the driving power source40G so that the driving shaft41extends horizontally and support the hydraulic pump unit300H so that the input shaft370extends horizontally, in a state of being attached to the vehicle frame30, as similar to the attachment frame500G.

Specifically, as shown inFIGS. 26-28, the attachment frame500H integrally includes the first side plate550aconfiguring the first motor supporting surface510a, the second side plate550bconfiguring the second motor supporting surface510b, a top plate560H extending in the width direction and in the fore-and-aft direction of the vehicle in a state of being substantially horizontally so as to connect the first and second side plates550a,550b, a first connecting plate570H extending in the vehicle width direction in a state of being substantially vertically so as to connect edges on one side (front edges in this embodiment) in the front and back direction of the vehicle of the first side plate550aand the second side plate550b, and a second connecting plate575H extending in the vehicle width direction in a state of being substantially vertically so as to connect edges on the other side (rear edges in this embodiment) in the front and back direction of the vehicle of the first side plate550aand the second side plate550b.

The driving power source40G is supported by the top plate560H.

That is, in the attachment frame500H, the top plate560H configures a driving source supporting surface for supporting the driving power source40G, as similar to the attachment frame500G.

Specifically, the top plate560H supports the driving power source40G so that the driving shaft41extends horizontally toward the front.

The top plate560H supports the driving power source40G so that at least a part of the driving power source40G is positioned below the top plate560H, as similar to the seventh embodiment.

Specifically, as shown inFIG. 28, the top plate560H is provided with a first opening561H corresponding to the driving power source40G. The driving power source40G is supported by the top plate560H by way of four rubber vibration isolators46arranged at the front and the back and at the left and the right, in a state of being within the first opening561H so that at least a part of the driving power source40G is positioned below the top plate560H.

The hydraulic pump unit300H is supported by the attachment frame500H in a state of being within a space surrounded by the first side plate550a, the second side plate550b, the first connecting plate570H, the second connecting plate575H and the top plate560H.

In the present embodiment, as shown inFIGS. 26-28, of the second connecting plate575H, an inner surface facing the first connecting plate570H configures a pump supporting surface for supporting the hydraulic pump unit300H.

Specifically, the second connecting plate575H is provided with an opening through which the input shaft370can pass.

The second connecting plate575H supports the hydraulic pump unit300H at the inner surface so that the input shaft370lies horizontally and projects outwardly from the space toward the approaching direction to the driving power source40G through the opening.

As shown inFIGS. 26 and 27, the first connecting plate570H is provided with openings through which the link mechanism37a,37bpass, respectively, and an opening through which the transmission shaft29passes.

In the present embodiment, the input shaft370is so configured that its rotational axis line is directed along the fore-and-aft direction of the vehicle as similar to the driving shaft41of the driving power source40G, but the position of the rotational axis line is off set in the vertical direction and in the vehicle width direction with respect to the driving shaft41.

Therefore, the traveling system power transmission mechanism10H is a pulley-belt transmission mechanism including the travel driving pulley11, the travel driven pulley12, and the travel belt13.

In order to allow the driving shaft41and the input shaft370to be connected by the traveling system power transmission mechanism10H, the top plate560H is provided with a second opening562H (seeFIG. 28) corresponding to the flywheel and the travel driving pulley11, in addition to the first opening561H.

As shown inFIG. 28, the reservoir tank900and the filter unit950are supported by the top plate560H at desired position other than the first and second openings561H,562H, as similar to the seventh embodiment.

The effects similar to the sixth and seventh embodiments are also obtained in the HST unit100H.

Preferably, as shown inFIGS. 26-28, the attachment frame500H may integrally include a first side extension plate580a(seeFIGS. 26 and 28) extending from the edge on the other side of the first side plate550atoward the other side in the front and back direction of the vehicle in a state of lying substantially vertically and connected to the top plate560H, a second side extension plate580b(seeFIG. 28) extending from the edge on the other side of the second side plate550btoward the other side in the front and back direction of the vehicle in a state of lying substantially vertically and connected to the top plate560H, and a third connecting plate585F (seeFIGS. 26 and 28) extending in the vehicle width direction in a state of lying substantially vertically so as to connect edges on the other side in the front and back direction of the vehicle of the first side extension plate580aand the second side extension580b, and a edge on the other side in the front and back direction of the vehicle of the top plate560H, thereby enhancing the strength of the attachment frame500H.

A hydraulic pump unit in which both the first and second hydraulic pump main bodies310a,310bare accommodated in a single pump case330F,330H has been explained by way of example in each of the above embodiments, but the present invention is not limited thereto.

In other words, a pair of first and second hydraulic pump units that are supported independently of each other by the attachment frame may be employed as the hydraulic pump unit.

In such embodiment, the first and second hydraulic pump units are fluidly connected to the first and second hydraulic motor units, respectively.

Further, in each of the above embodiments, the attachment frame500F-500H is so configured to support the driving power source40F,40G, but the present invention in not limited the configuration.

That is, it is possible that the attachment frame500F-500H are configured to support only the hydraulic pump unit300F or300H, the first hydraulic motor unit200a, the second hydraulic motor unit200band the reservoir tank900(and the independent filter unit950). In the configuration, the driving power source40F,40G are directly supported by the vehicle frame30.

Furthermore, in each embodiment, an example in which the first and second hydraulic pump main bodies310a,310bare independently fluidly connected to the first and second hydraulic motor main bodies210a,210b, respectively, is given by way of example, but the present invention is not limited thereto.

In other words, the first and second hydraulic motor main bodies210a,210bmay be fluidly connected by a pair of motor-side conduits, and the pair of motor-side conduits and a single traveling hydraulic pump main body may be fluidly connected.

For instance, one of the first or the second hydraulic pump main body310a,310bin each embodiment may be used as the traveling hydraulic pump main body.

In this case, the other one of the first or the second hydraulic pump main body310a,310bmay be omitted, or the other one of the first or the second hydraulic pump main body310a,310bmay be used as a hydraulic pressure source for other hydraulic equipments.

Furthermore, although, in each embodiment, the reservoir tank900and the filter unit950are supported by the top plates560f-560H, it is off course possible that the reservoir tank900and/or the filter unit950could be supported by the other portions of the attachment frames500F-500H.

This specification is by no means intended to restrict the present invention to the preferred embodiments set forth therein. Various modifications to the HST unit may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.