Hydraulic system for an automatic power transmission
US4020718A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 26, 1975 |
| Grant date | May 3, 1977 |
| Priority date | — |
| Expiry date | Feb 26, 1995 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2061/026
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A hydraulic system for an automatic power transmission of a motor vehicle and adapted for preventing creep of the motor vehicle when the vehicle comes to a complete halt. The hydraulic system includes a first shift valve responsive to throttle pressure and governor pressure to control supply of line pressure into servo means for actuating a friction element to provide lower gear reduction ratio, and a second shift valve responsive to released condition of an accelerator pedal of the vehicle for supplying line pressure into a governor pressure port of the first shift valve, whereby the first shift valve is moved in dependence on throttle pressure and line pressure into a position to supply line pressure into the servo means for thereby effecting shift into the lower gear reduction ratio in the power transmission. The hydraulic system may further include a third shift valve responsive to fully depressed condition of the accelerator pedal to supply line pressure into the first shift valve to apply line pressure thereto so that the shifting point is raised to a higher vehicle speed side during kickdown condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.