Patent US5399795A successfully refreshed from Google Patents.
Patent US3863523A successfully refreshed from Google Patents.
US3863523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic safety system for a vehicle transmission
Assignee: Caterpillar Inc
•
Filing: 1973-06-25
•
Granted: 1975-02-04
•
Expires: 1993-06-25
Abstract
Abstract A transmission control system includes controls for engaging speed ratio devices and directional devices. A safety valve functions to insure that initially, no fluid is supplied from a source to a speed ratio device unless the directional device control is in a neutral position. The safety valve shifts after a build up in pressure in such chosen speed ratio device. Such safety valve shift allows full pressure buildup in the speed ratio device, and also allows full pressure to be supplied to the chosen directional drive device upon shifting of the directional drive control from the neutral position.
Inventors
- 👤 James G Starling
- 👤 Harold A Mathes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:30
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/02; F16H61/0262; F16H61/0265; F16H61/0272; F16H61/70
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
304 words
In combination with a transmission having a plurality of fluid pressure actuated drive conditioning devices including a first group of drive conditioning devices and a second group of drive conditioning devices, and wherein application of fluid pressure to at least one device of each group establishes a selected one of a plurality of drive conditions through the transmission, a control system comprising: a source of fluid under pressure; safety valve means having first and second positions; a first selector valve communicating with said source with the safety valve means in its second position, and having a plurality of drive conditions for directing fluid to predetermined ones of said first group devices; a second selector valve communicating with said source with the safety valve means in its second position and having a plurality of drive positions for directing fluid to predetermined ones of said second group of devices, and having a neutral position which cuts off fluid to all of said second group of devices; the source of fluid pressure communicating with the first selector valve with the safety valve means in its first position only when the second selector valve is in its neutral position, to direct fluid to the predetermined one of the first group of devices; the safety valve means being biased into its first position to initially direct fluid from the fluid pressure source to the predetermined one of the first group of devices only when the second selector valve is in its neutral position; means for moving the safety valve means from its first to its second position upon buildup of fluid pressure in the predetermined one of said first group of devices; the movement of the safety valve means to its second position providing communication of the first and second selector valves with the source of fluid under pressure.
Claim 2
Dependent Claim
304 words
In combination with a transmission having a plurality of fluid pressure actuated drive conditioning devices including a first group of drive conditioning devices and a second group of drive conditioning devices, and wherein application of fluid pressure to at least one device of each group establishes a selected one of a plurality of drive conditions through the transmission, a control system comprising: a source of fluid under pressure; safety valve means having first and second positions; a first selector valve communicating with said source with the safety valve means in its second position, and having a plurality of drive conditions for directing fluid to predetermined ones of said first group devices; a second selector valve communicating with said source with the safety valve means in its second position and having a plurality of drive positions for directing fluid to predetermined ones of said second group of devices, and having a neutral position which cuts off fluid to all of said second group of devices; the source of fluid pressure communicating with the first selector valve with the safety valve means in its first position only when the second selector valve is in its neutral position, to direct fluid to the predetermined one of the first group of devices; the safety valve means being biased into its first position to initially direct fluid from the fluid pressure source to the predetermined one of the first group of devices only when the second selector valve is in its neutral position; means for moving the safety valve means from its first to its second position upon buildup of fluid pressure in the predetermined one of said first group of devices; the movement of the safety valve means to its second position providing communication of the first and second selector valves with the source of fluid under pressure.
Claim 3
Dependent Claim
31 words
The combination of claim 1 wherein said safety valve means comprise a housing having a bore therein, and a spool that is movable axially therein to said first and second positions.
Claim 4
Dependent Claim
62 words
The combination of claim 2 wherein the safety valve spool defines first and second annular channels, the source communicating with the first selector valve with the safety valve means in its first position through the first annular channel, the source communicating with the first and second selector valves with thE safety valve means in its second position through the second annular channel.
Claim 5
Dependent Claim
64 words
The combination of claim 3 wherein the second annular channel is subjected to fluid pressure buildup during the initial direction of fluid from the source to the predetermined one of the first group of devices with the safety valve means in its first position, and means for utilizing said fluid pressure buildup to overcome said bias to move said spool into its second position.
Claim 6
Dependent Claim
68 words
The combination of claim 4 wherein said safety valve spool defines an axial bore communicating with the second channel and extending therefrom in the direction in which the spool is biased, the pressure buildup in the second annular channel acting in the axial bore and outward of the end of the spool but within the housing to overcome the bias and move the spool into its second position.
Claim 7
Dependent Claim
17 words
The combination of claim 5 wherein the spool is biased into its first position by spring means.
References Cited (Backward Citations)
US3181394A
Cited
US3468194A
Cited
US3527326A
Cited
US3596536A
Cited
US3633440A
Cited
US3640146A
Cited
US3709065A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |