Patents by Inventor David B. Birchfield

David B. Birchfield 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).

  • Drain plug position indicator apparatus
    Patent number: 5047753
    Abstract: An apparatus including a plug detector mechanism mounted adjacent an interior surface of a drain plug aperture directed through a transom of a boat. The detecting means includes a spring-biased switch positionable from an extended position in the absence of a plug to a retracted position in the presence of a plug directed through the transom. The switch is cooperative with an audible member to effect alarm in the absence of the plug.
    Type: Grant
    Filed: May 29, 1990
    Date of Patent: September 10, 1991
    Inventor: David B. Birchfield