US3788401A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic circuit with valve to provide semi-float control of a dozer blade
Assignee: Caterpillar Inc
•
Filing: 1972-07-17
•
Granted: 1974-01-29
•
Expires: 1992-07-17
Abstract
Abstract There is disclosed a control circuit having a semi-float position for a bulldozer blade. The circuit includes selectively controllable check and relief valves operative to prevent the blade from dropping under the influence of gravity, but permits the blade to be moved under the influence of forces developed by a vehicle being pushed thereby.
Inventors
- 👤 J Scheidt
- 👤 R White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 16:28
CPC Classifications
F; F15; F15B; F15B13/00; F15B13/02; F15B13/04; E; E02; E02F; E02F3/00; E02F3/04; E02F3/76; E02F3/80; E02F3/84; E02F3/844
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
157 words
A hydraulic control system for raising and lowering a bulldozer blade, said system comprising: a bulldozer blade pivotally supported from a vehicle; a double acting hydraulic jack, having a raise end and a lower end, operatively connected to raise and lower said bulldozer blade; a source of pressurized fluid; selector valve means operatively connected to selectively direct said fluid to said raise and lower ends of the jack and including a float position; a pressure responsive check valve including a pressure control chamber operatively positioned to control flow of fluid to and from said raise end of said jack; means responsive to low pressure operative to relieve said control chamber; means operatively connected to said selector valve means and responsive to movement thereof to the float position to render said means responsive to low pressure inoperative; and, means responsive to high pressure operative to relieve said control chamber when said means responsive to low pressure is inoperative.
Claim 2
Dependent Claim
157 words
A hydraulic control system for raising and lowering a bulldozer blade, said system comprising: a bulldozer blade pivotally supported from a vehicle; a double acting hydraulic jack, having a raise end and a lower end, operatively connected to raise and lower said bulldozer blade; a source of pressurized fluid; selector valve means operatively connected to selectively direct said fluid to said raise and lower ends of the jack and including a float position; a pressure responsive check valve including a pressure control chamber operatively positioned to control flow of fluid to and from said raise end of said jack; means responsive to low pressure operative to relieve said control chamber; means operatively connected to said selector valve means and responsive to movement thereof to the float position to render said means responsive to low pressure inoperative; and, means responsive to high pressure operative to relieve said control chamber when said means responsive to low pressure is inoperative.
Claim 3
Dependent Claim
32 words
The control system of claim 1 wherein said means responsive to low pressure comprises a low pressure relief valve, and said means responsive to high pressure comprises a high pressure relief valve.
Claim 4
Dependent Claim
42 words
The control system of claim 2 wherein said means to render said low pressure valve inoperative comprises a rotary valve operative upon movement of said selector valve to the float position to block communication of said relief valve with said control chamber.
Claim 5
Dependent Claim
20 words
The control system of claim 3 comprising lost motion linkage means connecting said selector valve means to said rotary valve.
Claim 6
Dependent Claim
143 words
A hydraulic control system for controlling the vertical position of a bulldozer blade, said system comprising: a double acting hydraulic jack connected to a bulldozer blade, said jack having a raise end and a lower end; a source of pressurized fluid; selector valve means operatively connected to selectively direct said fluid to opposite ends of the jack and including a float position; a pressure responsive check valve including a pressure control chamber disposed to control flow of fluid from said raise end of said jack; means responsive to low pressure operative to relieve said control chamber; means operatively connected to said selector valve means and responsive to movement thereof to the float position to render said means responsive to low pressure inoperative; and, means responsive to high pressure operative to relieve said control chamber when said means responsive to low pressure is inoperative.
Claim 7
Dependent Claim
143 words
A hydraulic control system for controlling the vertical position of a bulldozer blade, said system comprising: a double acting hydraulic jack connected to a bulldozer blade, said jack having a raise end and a lower end; a source of pressurized fluid; selector valve means operatively connected to selectively direct said fluid to opposite ends of the jack and including a float position; a pressure responsive check valve including a pressure control chamber disposed to control flow of fluid from said raise end of said jack; means responsive to low pressure operative to relieve said control chamber; means operatively connected to said selector valve means and responsive to movement thereof to the float position to render said means responsive to low pressure inoperative; and, means responsive to high pressure operative to relieve said control chamber when said means responsive to low pressure is inoperative.
Claim 8
Dependent Claim
32 words
The control system of claim 5 wherein said means responsive to low pressure comprises a low pressure relief valve, and said means responsive to high pressure comprises a high pressure relief valve.
Claim 9
Dependent Claim
35 words
The control system of claim 6 wherein said means responsive to movement of said selector valve comprises a rotary valve; and, lost motion linkage means operatively connecting said rotary valve to said selector valve means.
Claim 10
Dependent Claim
28 words
The control system of claim 5 comprising lost motion linkage means operatively connecting said means responsive to movement of said selector valve means to said selector valve means.
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) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |