US3768570A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tractor hydraulic lift system
Assignee: Ford Motor Co
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Filing: 1972-06-28
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Granted: 1973-10-30
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Expires: 1992-06-28
Abstract
Abstract A tractor hydraulic lift control system is provided with a manually adjusted quadrant lever for determining the draft at which the tractor is to operate and a second manually adjusted quadrant lever for determining the implement height. The draft control may raise the implement above the height determined by the position control but may not lower it below the height determined by position control.
Inventors
- 👤 L Green
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:31
CPC Classifications
A; A01; A01B; A01B63/00; A01B63/02; A01B63/10; A01B63/111; A01B63/1117
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
201 words
In a tractor having an implement supporting hitch, a hydraulic cylinder for supporting the hitch at different elevations, a source of fluid under pressure, a control valve for admitting fluid to or releasing fluid from the cylinder, draft control means for controlling operation of the control valve responsive to implement draft, position control means for controlling operation of the valve responsive to height of the implement supporting hitch, the position control means including a servo lever operated responsive to height of the hitch, the draft control means including a second servo lever operated responsive to implement draft, the two servo levers each being mounted adjacent one end thereof on a common pivot adjacent the control valve, a lever mounted for rotation about a fixed center and supporting the pivot for movement in a direction to cause the lever to engage and operate the control valve, whereby the servo levers are supported and either servo lever may operate the valve, the implement draft control means serving to lift the hitch above the level established by the position control means as required to maintain preselected implement draft but being inoperative to lower the hitch below the level established by the position control means.
Claim 2
Dependent Claim
201 words
In a tractor having an implement supporting hitch, a hydraulic cylinder for supporting the hitch at different elevations, a source of fluid under pressure, a control valve for admitting fluid to or releasing fluid from the cylinder, draft control means for controlling operation of the control valve responsive to implement draft, position control means for controlling operation of the valve responsive to height of the implement supporting hitch, the position control means including a servo lever operated responsive to height of the hitch, the draft control means including a second servo lever operated responsive to implement draft, the two servo levers each being mounted adjacent one end thereof on a common pivot adjacent the control valve, a lever mounted for rotation about a fixed center and supporting the pivot for movement in a direction to cause the lever to engage and operate the control valve, whereby the servo levers are supported and either servo lever may operate the valve, the implement draft control means serving to lift the hitch above the level established by the position control means as required to maintain preselected implement draft but being inoperative to lower the hitch below the level established by the position control means.
Claim 3
Dependent Claim
38 words
In a tractor as claimed in claim 1, the other ends of the servo levers each being positioned by a manually adjusted quadrant lever through a linkage making sliding contact with said other ends of the servo levers.
Claim 4
Dependent Claim
47 words
In a tractor as claimed in claim 2, the draft control servo lever having a one-way connection with the linkage associated with its quadrant lever to permit said servo lever to become disengaged from said linkage, whereby the hitch height is limited by the position control mechanism.
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) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |