Patent US3922931A successfully refreshed from Google Patents.
US3922931A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Speed change device for tractor transmissions
Assignee: Kubota Corp
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Filing: 1974-01-04
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Granted: 1975-12-02
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Expires: 1994-01-04
Abstract
Abstract Improvements in a transmission of the three-shaft type in which a speed change system for driving the tractor and a speed change system for power takeoff are disposed in parallel to each other on the opposite sides of a main input shaft having gears for power transmission. A hydraulic transmission unit employed as the tractor-driving speed change system includes a hydraulic pump, a charge pump and a hydraulic motor which are aligned coaxially as a unit. The hydraulic transmission unit operates to drive the tractor at steplessly variable speeds, whilst the power takeoff system comprising gears gives stepwisely variable speeds. A secondary speed change unit is disposed in the rear of the hydraulic transmission unit and a power takeoff shaft extends rearward from the power takeoff system to provide live power takeoff independently of the speed of tractor and ground power takeoff in timed raltion to the tractor speed. Means for supporting the hydraulic transmission, for mounting and removing the same and for filtering and cooling the working oil are also disclosed.
Inventors
- 👤 Masahide Osujyo
- 👤 Naoya Tuda
- 👤 Yoshimi Ota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:12
CPC Classifications
F; F16; F16H; F16H47/00; F16H47/02; F16H47/04; Y; Y10; Y10T; Y10T74/00; Y10T74/19; Y10T74/19023; Y10T74/19037; Y10T74/19074; Y10T74/19079; Y10T74/19167; Y10T74/21; Y10T74/2186
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
259 words
A transmission comprising the three systems of an input system including a main input shaft operable to transmit power when a clutch is engaged and provided with a plurality of gears; a driving speed change system comprising a hydraulic pump and a hydraulic motor hydraulically connected to the hydraulic pump, the hydraulic pump including a pump gear meshing with one of the gears of the input system; and a power takeoff speed change system including a power takeoff speed change shaft having a suitable number of gears meshable with the gears of the input system; the driving speed change systme and the power takeoff speed change system being supported in parallel to each other in the input system interposed therebetween, characterized by a hydraulic transmission unit comprising a capacity-variable hydraulic pump unit including a pump shaft and a hydraulic motor unit of constant capacity including a motor shaft, the pump shaft being fixedly provided with a pump gear meshing with the gear of the input system, the pump shaft and the motor shaft being coaxially aligned with each other, a center section being provided between and held by the units in a readily detachable manner and incorporating a charge pump mounted on the pump shaft, the pump unit, charge pump and motor unit being arranged in series, the hydraulic transmission unit serving as the driving speed change system and being housed in a transmission case and thereby supported removably, the transmission further being characterized by a valve unit removably mounted on the center section of the hydraulic transmission unit.
Claim 2
Dependent Claim
259 words
A transmission comprising the three systems of an input system including a main input shaft operable to transmit power when a clutch is engaged and provided with a plurality of gears; a driving speed change system comprising a hydraulic pump and a hydraulic motor hydraulically connected to the hydraulic pump, the hydraulic pump including a pump gear meshing with one of the gears of the input system; and a power takeoff speed change system including a power takeoff speed change shaft having a suitable number of gears meshable with the gears of the input system; the driving speed change systme and the power takeoff speed change system being supported in parallel to each other in the input system interposed therebetween, characterized by a hydraulic transmission unit comprising a capacity-variable hydraulic pump unit including a pump shaft and a hydraulic motor unit of constant capacity including a motor shaft, the pump shaft being fixedly provided with a pump gear meshing with the gear of the input system, the pump shaft and the motor shaft being coaxially aligned with each other, a center section being provided between and held by the units in a readily detachable manner and incorporating a charge pump mounted on the pump shaft, the pump unit, charge pump and motor unit being arranged in series, the hydraulic transmission unit serving as the driving speed change system and being housed in a transmission case and thereby supported removably, the transmission further being characterized by a valve unit removably mounted on the center section of the hydraulic transmission unit.
Claim 3
Dependent Claim
41 words
A transmission as set forth in claim 1, wherein the hydraulic transmission unit is supported at its front and rear portions and the transmiSsion case is provided with support brackets for supporting the opposite side portions of the hydraulic transmission unit.
Claim 4
Dependent Claim
72 words
A transmission as set forth in claim 1 wherein the pump shaft of the hydraulic transmission unit is supported by a bearing, and a space greater than the axial length of the pump shaft received in the bearing is provided between the end of the motor shaft and a shaft end opposing the motor shaft, the motor shaft being connectable to the opposing shaft end by a coupling extending over the space.
Claim 5
Dependent Claim
53 words
A transmission as set forth in claim 1 wherein a pump space and a motor space are formed in a housing for the hydraulic pump unit and in a housing for the hydraulic motor unit respectively, and the center section is formed with oil passages through which the spaces communicate with each other.
Claim 6
Dependent Claim
54 words
The transmission as set forth in claim 1 wherein center sections are clamped between a housing for the hydraulic pump and a housing for the hydraulic motor and the center sections are formed with oil passages through which a hydraulic pump space within the housing communicates with a hydraulic motor space within the housing.
Claim 7
Dependent Claim
99 words
The transmission as set forth in claim 1 wherein a speed change controlling mechanism is provided for the hydraulic transmission unit including the hydraulically connected hydraulic pump and the hydraulic motor, the controlling mechanism including a swash plate lever for controlling the hydraulic pump, a driving lever attached to an operating rod by a spring member and a connecting member connecting the swash plate lever to the driving lever, the driving lever having a shorter length than the swash plate lever, the spring member having a spring force to prevent the swash plate lever from driving the operating rod.
Claim 8
Dependent Claim
61 words
The transmission as set forth in claim 1 further comprising means for cooling working oil including a cooling duct through which a relief valve for the charge pump for the hydraulic pump communicates with an oil tank and an oil cooler disposed at an intermediate portion of the duct and cooled by a radiator for cooling the engine of the tractor.
Claim 9
Dependent Claim
55 words
The transmission as set forth in claim 1 wherein the hydraulic transmission unit is housed in a transmission case serving as an oil tank, the transmission case having therein a primary filter and a secondary filter having a higher filtering ability than the primary filter is attached to a covering member for the transmission unit.
Claim 10
Dependent Claim
24 words
The transmission as set forth in claim 8 wherein the secondary filter is positioned at least above the oil level in the transmission case.
Claim 11
Dependent Claim
37 words
The transmission as set forth in claim 9 wherein a communicating member having a communicating passage is disposed between the secondary filter and a valve unit mounted on the hydraulic transmission unit to provide an oil passage.
Claim 12
Dependent Claim
32 words
The transmission as set forth in claim 10 wherein a plug is removably attached to the communicating member to cause the oil passage to communicate with the atmosphere through the plugged portion.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |