US3640146A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic safety override valve
Assignee: Caterpillar Inc
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Filing: 1970-05-28
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Granted: 1972-02-08
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Expires: 1990-05-28
Abstract
Abstract A hydraulic control valve for controlling a vehicle transmission comprising a manually actuable position selector valve for alternatively directing hydraulic fluid to first or second position clutches of the transmission from a neutral position, a pressure modulating relief valve for modulating the operation of the position selector valve, and a safety override valve linked to the position selector valve for automatically returning the position selector valve to the neutral position when hydraulic pressure is low thereby avoiding system damage.
Inventors
- 👤 Randolph C Barnes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:25
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/16; F15; F15B; F15B20/00; F15B20/004; F16H61/12; F16H2061/1232; F16H2061/1256; F16H2061/126; F16H2061/1264; F16H59/00; F16H59/02; F16H59/08; F16H59/68; F16H61/02; F16H61/0262; F16H61/0274; F16H61/68; F16H61/684; F16H61/686; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86485; Y10T74/00; Y10T74/19; Y10T74/19219; Y10T74/19377; Y10T74/19414; Y10T74/19419; Y10T74/19423; Y10T74/19428; Y10T74/19433
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
190 words
In a transmission control system, a control valve comprising a housing, a position selector valve means within said housing for actuating a transmission, said position selector valve means having a first and a second position on opposite sides of a central, neutral position, said position selector valve means serving to direct pressure fluid from a source of fluid pressure to a transmission for actuation of corresponding first or second positions of said transmission, means for returning said position selector valve means to said central, neutral position when fluid pressure in said position selector valve means drops below a predetermined value for a predetermined time such as when malfunction or normal shutdown of the fluid power source occurs, thereby preventing system damage and wherein the means for returning the position selector valve means to the central, neutral position comprises safety valve means within said housing, means operatively connecting said safety valve means to said position selector valve means, and means communicating said safety valve means with fluid pressure whereby movement of said safety valve means in response to low fluid pressure results in coordinate movement of said position selector valve means.
Claim 2
Dependent Claim
190 words
In a transmission control system, a control valve comprising a housing, a position selector valve means within said housing for actuating a transmission, said position selector valve means having a first and a second position on opposite sides of a central, neutral position, said position selector valve means serving to direct pressure fluid from a source of fluid pressure to a transmission for actuation of corresponding first or second positions of said transmission, means for returning said position selector valve means to said central, neutral position when fluid pressure in said position selector valve means drops below a predetermined value for a predetermined time such as when malfunction or normal shutdown of the fluid power source occurs, thereby preventing system damage and wherein the means for returning the position selector valve means to the central, neutral position comprises safety valve means within said housing, means operatively connecting said safety valve means to said position selector valve means, and means communicating said safety valve means with fluid pressure whereby movement of said safety valve means in response to low fluid pressure results in coordinate movement of said position selector valve means.
Claim 3
Dependent Claim
44 words
The invention of claim 1 further including a means which fluidly communicates the safety valve means with the position selector valve means and which operates to allow a normal shift cycle to occur without signaling the safety valve means to commence its centering function.
Claim 4
Dependent Claim
28 words
The invention of claim 2 further including a pressure modulating relief valve means within said housing which operates to modulate the operation of said position selector valve means.
Claim 5
Dependent Claim
29 words
The invention of claim 2 wherein the means which fluidly communicates the safety valve means comprises a one-way check having an orifice therethrough and a spring biasing said check.
Claim 6
Dependent Claim
133 words
The invention of claim 2 wherein the safety valve means further comprises a generally rodlike safety spool having a projecting land thereon, said safety spool being contained in said housing and being axially movably retained therein by identical safety pistons having axial bores encompassing opposite ends of said safety spool, said pistons being axially movable in separate axial bores in said housing, which bores are separated by a central, annular land, said pistons being biased toward each other by spring means contained within said housing bores, and said means operatively connecting said safety valve means comprises a pivot lever pivotally mounted intermediate its ends on a pivot mount and having one end operatively connected to one end of said safety spool and the other end operatively connected to said position selector valve means.
Claim 7
Dependent Claim
106 words
The invention of claim 5 wherein the spring means comprise springs having spring constants such that when operating pressures are maintained in the position selector valve means the fluid pressure communicated to the safety valve means will cause the pistons to compress the springs and allow free movement of the safety spool and when fluid pressure drops below a minimum value the springs will force the pistons against the center land and projecting land on the safety spool from opposite sides such that the safety spool will be centered and thereby center the position selector spool in the neutral position by means of the pivot lever.
Claim 8
Dependent Claim
49 words
The invention of claim 6 wherein the position selector valve means comprises a position spool having a pair of position spool lands thereon, said lands being axially movable within mating axial bores and wherein one end of said position spool is adapted for operative attachment with a shift lever.
Claim 9
Dependent Claim
35 words
The invention of claim 7 further including first, neutral and second position detent annuli on said position spool, and a detent means mounted to cooperate with said annuli in order to maintain a particular position.
Claim 10
Dependent Claim
35 words
The invention of claim 7 wherein said position spool lands define edges and wherein a plurality of axially oriented slots are extant on the edges thus defined thereby permitting finer control of the working fluid.
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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) | 1975-02-07 | 1975-08-09 | 1976-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-07 | 1979-08-09 | 1980-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-07 | 1983-08-09 | 1984-02-08 | $7700.00 | Window Closed / Lapsed |