Fluid circuit for shifting a transmission
US3998111A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 24, 1975 |
| Grant date | Dec 21, 1976 |
| Priority date | — |
| Expiry date | Mar 24, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/86702
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A hydraulic system responsive to movement of a shift lever energizes selected pairs of drive engaging devices in a vehicle transmission by applying a gradual rise in pressure to the selected speed drive engaging device and by applying a delayed and a lesser gradual pressure rise to a selected directional drive engaging device. The circuit neutralizes the transmission by blocking fluid pressure from at least one of the devices if the vehicle engine is started with the shift lever at a position other than neutral and also neutralizes the transmission when the vehicle brakes are applied while still maintaining full fluid pressure to other vehicle components. These functions are accomplished by a combination of a pair of selector valves, a pressure modulation valve assembly and a greatly simplified and compact spool differential check and safety valve.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.