Patent US3924689A successfully refreshed from Google Patents.
US3924689A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulically controlled grader-leveler adapted for trailing by tractors
Assignee: Technion Research and Development Foundation Ltd
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Filing: 1973-12-20
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Granted: 1975-12-09
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Expires: 1993-12-20
Abstract
Abstract A chassis, adapted to be connected to a farm tractor, supports a blade for grading and levelling; the blade is rotatable with respect to the chassis. The angle of the blade is set by a hydraulic transmission, such as a linear or rotary hydraulic motor controlled by a direction controlled valve. Mechanical output from the hydraulic motor is connected to the blade support, typically a turntable, to set the blade angle as determined by the application of hydraulic pressure. The blade can be fixed in position by engaging tooth-and-detent elements, one of them being respectively fixed to the chassis and the other formed on a turntable which is rotatable with the blade.
Inventors
- 👤 Gedalyahu Manor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:12
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/22; E02F9/2203; E02F3/00; E02F3/04; E02F3/76; E02F3/7663; E02F3/7668; E02F3/80; E02F3/84; E02F3/844; Y; Y10; Y10S; Y10S37/00; Y10S37/907
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
251 words
Off-center overload protected grader-leveler apparatus comprising a chassis having means at its forward end for trailing attachment to a farm tractor and, at its rear end, means for supporting the chassis above ground, said tractor having a hydraulic system including a collecting vessel; a blade support means, and means rotatably securing the blade support means to the chassis to enable the support means to swing about an essentially vertical axis to permit selective positioning of the support means with respect to said chassis; a grading and leveling blade supported by the support means; blade positioning means, quick release means including a hydraulic piston motor having a cylinder; means connecting the movable force transmitting portion of the hydraulic motor to the blade support means; and means controlling application of pressurized fluid, selectively, to a side of the piston of the motor in order to rotate the blade support means, and hence the blade about its axis and bring it into a desired position; wherein, to avoid blade damage upon encountering an off-center overload, the improvement comprises controlled quick fluid release means to open and release fluid from the respective overloaded side of the piston into the collecting vessel whenever the fluid pressure on the piston exceeds a limit defined by an excessive off-center load on the blade, release of fluid permitting the piston to move freely and to allow the blade support means with the blade attached thereto to turn freely about its axis and thereby to prevent damage to the apparatus.
Claim 2
Dependent Claim
251 words
Off-center overload protected grader-leveler apparatus comprising a chassis having means at its forward end for trailing attachment to a farm tractor and, at its rear end, means for supporting the chassis above ground, said tractor having a hydraulic system including a collecting vessel; a blade support means, and means rotatably securing the blade support means to the chassis to enable the support means to swing about an essentially vertical axis to permit selective positioning of the support means with respect to said chassis; a grading and leveling blade supported by the support means; blade positioning means, quick release means including a hydraulic piston motor having a cylinder; means connecting the movable force transmitting portion of the hydraulic motor to the blade support means; and means controlling application of pressurized fluid, selectively, to a side of the piston of the motor in order to rotate the blade support means, and hence the blade about its axis and bring it into a desired position; wherein, to avoid blade damage upon encountering an off-center overload, the improvement comprises controlled quick fluid release means to open and release fluid from the respective overloaded side of the piston into the collecting vessel whenever the fluid pressure on the piston exceeds a limit defined by an excessive off-center load on the blade, release of fluid permitting the piston to move freely and to allow the blade support means with the blade attached thereto to turn freely about its axis and thereby to prevent damage to the apparatus.
Claim 3
Dependent Claim
22 words
Apparatus according to claim 1, wherein the blade support means comprises a normally horizontal turntable, the blade being secured to the turntable.
Claim 4
Dependent Claim
75 words
Apparatus according to claim 1, wherein the release means on each side of the cylinder comprises a relief valve which permits, at excess pressure, fluid to be drained from its side and to flow into the collecting vessel; and an anti-cavitation valve is connected in parallel with the relief valve and permitting fluid from the collecting vessel to enter the other side of the cylinder as the piston is moving under influence of an overload.
Claim 5
Dependent Claim
53 words
Apparatus according to claim 3, wherein the release means comprise one single relief valve connected to both sides of the piston housing; one check-valve each connecting the sides of the cylinder to the single relief valve; and two anti-cavitation valves provided between the two sides of the pistOn housing and the collecting vessel.
Claim 6
Dependent Claim
91 words
Apparatus according to claim 1, comprising a solenoid-operated direction control valve connected to control the hydraulic motor and to actuate the motor in the required direction by selective energization of the solenoid controlled valve; and wherein the release means comprises a pressure switch, each, connected hydraulically to one side of the cylinder, and electrically to one of the solenoids of the direction control valve, thereby moving the latter into a position allowing the outflow of fluid from the housing on the excess-pressure side and to admit fluid to the opposite side.
Claim 7
Dependent Claim
27 words
Apparatus according to claim 1, wherein the means for supporting the chassis above ground comprises at least one wheel attached to the rear part of the chassis.
Claim 8
Dependent Claim
19 words
Apparatus according to claim 1, wherein a plurality of wheels are provided, said wheels being directionally self-adjusting caster wheels.
Claim 9
Dependent Claim
28 words
Apparatus according to claim 1, wherein the means for supporting the chassis above ground level comprises at least one roller attached to the rear part of the chassis.
Claim 10
Dependent Claim
13 words
Apparatus according to claim 1, wherein the blade support means comprises a turntable.
Claim 11
Dependent Claim
33 words
Apparatus according to claim 1, wherein the controlled quick fluid release means comprises a relief valve, each, located at either side of the piston to release pressurized fluid from a respective side thereof.
Claim 12
Dependent Claim
71 words
Apparatus according to claim 1, wherein the controlled quick fluid release means comprises a relief valve which permits, at excess pressure, fluid to be drained from its side and to flow into the collecting vessel; and an anti-cavitation valve connected in parallel with the relief valve and permitting fluid from the collecting vessel to enter the other side of the cylinder as the piston is moving under influence of an overload.
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) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |