Patents by Inventor David L. Fochtman

David L. Fochtman has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4252148
    Abstract: A hydraulic control for an automatic transmission has a plurality of shift control valves for controlling the interchange of drive ratios within the transmission. The shift control valves each have a control chamber subjected to substantially constant pressure and a shift control chamber having an area proportional to the respective control chamber which is subjected to a variable control pressure. The variable control pressure is controlled at discrete levels by a single pulse width modulator (PWM) solenoid. The respective area ratios of the shift control chambers to the controlled chambers determines the distinct shift point of each shift valve.
    Type: Grant
    Filed: August 6, 1979
    Date of Patent: February 24, 1981
    Assignee: General Motors Corporation
    Inventors: David L. Fochtman, William J. Vukovich