Patent US4667536A successfully refreshed from Google Patents.
US4667536A
Expired / Lapsed
US
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Hydrostatic/mechanical transmission system
Assignee: ZF Friedrichshafen AG
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Filing: 1984-09-10
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Granted: 1987-05-26
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Expires: 2004-09-10
Abstract
Abstract A hydrostatic/mechanical transmission system for motor vehicles having an engine coupled with a multi-speed mechanical transmission and a hydrostatic transmission including an accessory drive connectable to activate a variable displacement hydropump that is hydraulically connected with hydromotor; wherein, in one mode of operation, the hydrostatic transmission is operated, with the mechanical transmission in neutral, and the hydromotor drives the vehicle by way of a stepdown gear, wherein the stepdown gear drive is a multistep power transmission and wherein when in the one mode, the hydromotor drives a secondary gear shaft of the multi-speed transmission, the connection of this one mode being possible only in the neutral position of the multi-speed transmission.
Inventors
- 👤 Friedrich Ehrlinger
- 👤 Egon Mann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:31
CPC Classifications
B; B60; B60K; B60K17/00; B60K17/04; F; F16; F16H; F16H47/00; F16H47/02; Y; Y10; Y10T; Y10T74/00; Y10T74/19; Y10T74/19023; Y10T74/19037
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
153 words
A hydrostatic/mechanical transmission system for motor vehicles having an engine coupled with a multi-speed mechanical transmission, a secondary gear shaft connected to said mechanical transmission, a hydrostatic transmission including an accessory drive connectable to activate a variable displacement hydropump that is hydraulically connected with a hydromotor, and said hydromotor drives the vehicle by way of a intermediate gearbox connected to said secondary gear shaft, characterized in that said intermediate gearbox is a multistep power transmission connectable under load and when in creep drive, said hydromotor drives the secondary gear shaft of said multi-speed transmission, the connection of said creep drive being possible only in the neutral position of said multi-speed transmission, circuit interruption of said intermediate gearbox occurs automatically depending upon speed and load of the engine, and a filling pump, which supplies oil to said hydrostatic drive, also supplies oil to friction clutches which connect said hydrostatic drive to said intermediate gearbox.
Claim 2
Dependent Claim
153 words
A hydrostatic/mechanical transmission system for motor vehicles having an engine coupled with a multi-speed mechanical transmission, a secondary gear shaft connected to said mechanical transmission, a hydrostatic transmission including an accessory drive connectable to activate a variable displacement hydropump that is hydraulically connected with a hydromotor, and said hydromotor drives the vehicle by way of a intermediate gearbox connected to said secondary gear shaft, characterized in that said intermediate gearbox is a multistep power transmission connectable under load and when in creep drive, said hydromotor drives the secondary gear shaft of said multi-speed transmission, the connection of said creep drive being possible only in the neutral position of said multi-speed transmission, circuit interruption of said intermediate gearbox occurs automatically depending upon speed and load of the engine, and a filling pump, which supplies oil to said hydrostatic drive, also supplies oil to friction clutches which connect said hydrostatic drive to said intermediate gearbox.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-25 | 1990-11-24 | 1991-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-25 | 1994-11-24 | 1995-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-25 | 1998-11-24 | 1999-05-26 | $7700.00 | Window Closed / Lapsed |