Machine element or mechanism – Power take-off – From shaft extension
Reexamination Certificate
2000-03-03
2002-03-26
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Power take-off
From shaft extension
C074S60600R
Reexamination Certificate
active
06360623
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a transmission system in a working vehicle comprising a front housing and a transmission case which are arranged in series in a longitudinal direction of the vehicle and are fastened together. The front housing includes at its front end portion an engine flywheel, and the transmission case includes at least one speed change mechanism. In such a working vehicle, the present invention particularly relates to a transmission system in which two kinds of supplementary speed change mechanisms, which are connected in series, are provided in the front housing so as to effectively use the inside of the front housing.
BACKGROUND OF THE INVENTION
In a working vehicle comprising a front housing, including at its front end portion an engine flywheel, and a transmission case, including at least one speed change mechanism, which are arranged in series and are fastened together, it is well known from, for example, U.S. Pat. Nos. 5,058,455 and 5,617,936 that a supplementary speed change mechanism such as a direction-reversing mechanism or high/low speed-selecting mechanism is provided in the front housing. However, it has not been known yet that two kinds of such supplementary speed change mechanisms which are connected in series are provided in the front housing.
However, it would be very advantageous if such two kinds of supplementary speed change mechanisms could be provided in the front housing in a simple structure without enlarging substantially the length of the front housing. In such a case, a variety of speed change transmissions could be offered without any substantial change in the speed change mechanism in the transmission case by omitting any one of the supplementary speed change mechanisms in the front housing.
Accordingly, a primary object of the present invention is to provide a novel transmission system in which two kinds of supplementary speed change mechanisms, namely a direction-reversing mechanism and a high/low speed-selecting mechanism which are connected in series, are provided in a front housing of a working vehicle.
An attendant object of the invention is to provide a transmission system which is easy in assembly notwithstanding the provision of two kinds of supplementary speed change mechanisms.
Another attendant object is to provide a transmission system which is simple in structure and which does not lengthen the front housing.
SUMMARY OF THE INVENTION
The present invention relates to a transmission system in a working vehicle comprising a front housing (
1
), including at its front end portion an engine flywheel (
6
), and a transmission case (
2
), including at least one speed change mechanism (
17
,
20
), which are arranged in series in a longitudinal direction of the vehicle and are fastened together. The transmission system according to the present invention is characterized in:
that there are provided in the front housing (
1
) a primary drive shaft (
8
) which is co-axial with the engine flywheel (
6
) and is adapted to be driven to rotate by the engine flywheel, a transmission shaft (
11
) which is arranged in parallel with the primary drive shaft, and an output shaft (
13
) which is co-axial with the primary drive shaft, the output shaft (
13
) being connected to the speed change mechanism (
17
,
20
); and
that a first two-ratio supplementary speed change mechanism (
12
) is disposed between the primary drive shaft (
8
) and the transmission shaft (
11
) and a second two-ratio supplementary speed change mechanism (
14
) is disposed between the transmission shaft (
11
) and the output shaft (
13
), one of the first and second supplementary speed change mechanism (
12
) being formed into a direction-reversing mechanism and the other of the first and second supplementary speed change mechanism (
14
) being formed into a high/low speed-selecting mechanism.
The primary drive shaft (
8
), provided in the front housing (
1
) such that it is co-axial with the engine flywheel (
6
), can be connected to the flywheel in a simplest manner. Because the primary drive shaft (
8
) and the output shaft (
13
) are arranged co-axially with each other, a rear end portion of the primary drive shaft and a front end portion of the output shaft can be supported by a single bearing support bore which is formed in and through a common bearing support wall. The first two-ratio supplementary speed change mechanism (
12
) and the second two-ratio supplementary speed change mechanism (
14
) are connected in series to each other by the transmission shaft (
11
) which is commonly employed for providing the first and second supplementary speed change mechanisms (
12
,
14
), so that two kinds of supplementary speed change mechanisms which are connected in series are provided by employing a minimum number of the three shafts (
8
,
11
,
13
). Consequently, two kinds of the supplementary speed change mechanisms are provided in the front housing without any substantial enlargement of the housing. A variety of speed change transmissions can be offered without any substantial change in the speed change mechanism (
17
,
20
) in the transmission case (
2
) by connecting between the primary drive shaft and the transmission shaft or between the transmission shaft and the output shaft through meshing gears in place of the first or second supplementary speed change mechanism.
For facilitating the assembly, it is preferred that the front housing (
1
) includes a first bearing support wall (
1
a
) disposed before the first supplementary speed change mechanism (
12
) and a second bearing support wall (
4
) disposed between the first and second supplementary speed change mechanisms (
12
,
14
), and that a third bearing support wall (
5
) disposed behind the second supplementary speed change mechanism (
14
) is provided at a location adjacent to a rear end of the front housing (
1
), the second bearing support wall (
4
) being removably secured to the front housing (
1
) and the third bearing support wall (
5
) being removably secured to the front housing (
1
) or to the transmission case (
2
). According to this structure, the first supplemetary speed change mechanism (
12
) can be assembled into the front housing (
1
) from the rear end thereof using the removable second bearing support wall (
4
) as a support therefor and, then, the second supplementary speed change mechanism (
14
) can be assembled into the front housing (
1
) from the rear end thereof using the removable third bearing support wall (
5
) as a support therefor.
The second supplementary speed change mechanism (
14
) can be formed into an easily operable fluid-operated type in which two clutches (
45
,
46
) which are selectively supplied with fluid pressure for performing two-ratio speed change transmission are mounted on the transmission shaft (
11
). In this case, it is preferred that the transmission shaft (
11
) includes at least one fluid passage (
61
) for supplying operating fluid to the clutches (
45
,
46
) and a lubricant passage (
69
) for supplying lubricant to the clutches (
45
,
46
), a rotary joint (
65
) for connecting the fluid passage (
61
) to a stationary fluid passage (
67
) being formed within the second bearing support wall (
4
) and another rotary joint (
70
) for connecting the lubricant passage (
69
) to a stationary lubricant passage (
73
) being formed within the first bearing support wall (
1
a
). According to this structure, the rotary joint (
65
) for the fluid passage in the transmission shaft and the rotary joint (
70
) for the lubricant passage in the transmission shaft are formed at locations spaced from each other in a longitudinal direction of the transmission shaft so that the thickness of each of the first and second bearing support walls (
1
a,
4
) can be made as small as possible, whereby enlargement of the length of the front housing (
1
) can be avoided.
More preferably, one of the clutches (
45
) is formed into a fluid-actuated frictional clutch having a first set of frictional elements (
47
,
48
), a first piston (
49
) for engaging b
Estremsky Sherry
Kanzaki Kokyukoki Mfg. Co. Ltd.
Pang Roger
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