US3732933A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tractor hydraulic lift system
Assignee: Ford Motor Co
•
Filing: 1971-06-11
•
Granted: 1973-05-15
•
Expires: 1991-06-11
Abstract
Abstract A tractor hydraulic lift system in which the lift system may be controlled by driveline torque, by draft sensed by one of the tractor hitch links or by a position control cam. The mechanism is arranged to permit combinations of position control with draft control and with torque control.
Inventors
- 👤 W Foxwell
- 👤 J Parsons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:57
CPC Classifications
A; A01; A01B; A01B63/00; A01B63/02; A01B63/10; A01B63/111; A01B63/1117
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
192 words
In a tractor having an engine, a transmission, ground driving wheels, a drive train extending between the transmission and ground driving wheels, an implement supporting hitch, a source of hydraulic fluid under pressure, a lift cylinder for controlling the height of the implement supporting hitch, and a control valve for regulating admission of fluid to and release of fluid from said cylinder, the improvement comprising: a servo-lever means coupled to said control valve, a draft sensing means coupled to the servo-lever means through a selector rod to actuate the control valve to raise or lower the implement supporting hitch in response to deviations from a predetermined draft load on the tractor, a torque-sensing means in the drive train coupled to the servolever means through the selector rod to actuate the control valve to raise or lower the implement supporting hitch in response to deviations in drive line torque above or below a predetermined norm, and a control means coupled to the servo-lever means to pre-set the control valve to automatically maintain the height of the implement hitch at a predetermined setting when the draft and torque conditions are at the desired norm.
Claim 2
Dependent Claim
192 words
In a tractor having an engine, a transmission, ground driving wheels, a drive train extending between the transmission and ground driving wheels, an implement supporting hitch, a source of hydraulic fluid under pressure, a lift cylinder for controlling the height of the implement supporting hitch, and a control valve for regulating admission of fluid to and release of fluid from said cylinder, the improvement comprising: a servo-lever means coupled to said control valve, a draft sensing means coupled to the servo-lever means through a selector rod to actuate the control valve to raise or lower the implement supporting hitch in response to deviations from a predetermined draft load on the tractor, a torque-sensing means in the drive train coupled to the servolever means through the selector rod to actuate the control valve to raise or lower the implement supporting hitch in response to deviations in drive line torque above or below a predetermined norm, and a control means coupled to the servo-lever means to pre-set the control valve to automatically maintain the height of the implement hitch at a predetermined setting when the draft and torque conditions are at the desired norm.
Claim 3
Dependent Claim
73 words
In a tractor according to claim 1, in which: a selector rod movement programming means is interposed between the selector rod and the draft and torque-sensing means, and a selector rod positioning means coupled to the selector rod is operable to position the latter relative to the programming means so that the selector rod is responsive to a resultant movement of the sensing means and the setting of the hitch height control means.
Claim 4
Dependent Claim
108 words
In a tractor according to claim 2, in which: the programming means comprises a first profiled elongated member pivotally supported on a part Of the draft sensing means and a second profiled member pivotally supported on a part of the torque sensing means, the first profiled member being movable in response to draft-sensing deviations as modified by hitch height setting to thereby vary the degree of actuation of the control valve by the selector rod, and the second profiled member being movable in response to torque-sensing deviations as modified by hitch height setting to thereby vary the degree of actuation of the control rod by the selector rod.
Claim 5
Dependent Claim
51 words
In a tractor according to claim 3, in which: the profiled members are pivotally connected to each other at their ends opposite their pivotally supported ends, the selector rod when positioned opposite the pivotal connection being in a neutral position relative to the draft sensing means and the torque sensing means.
Claim 6
Dependent Claim
56 words
In a tractor according to claim 4, in which: the first and second profiled members lie in end to end relationship and provide a control surface lying generally in a circular arc about a pivot located intermediate the ends of the servo-lever means, the selector rod being swingable about the last mentioned pivot along said arc.
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) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |