Patents by Inventor Joseph L. Duncan

Joseph L. Duncan 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).

  • Safety devices for overhead garage door springs
    Patent number: 4640049
    Abstract: A safety device for overhead garage and like door structures having a counterbalance spring structure including a coil spring which includes a safety cable extending through the open center of the coil spring and adjustably anchored at each end to the garage structure so as to be placed under sufficient tension to contain the spring against substantial horizontal or vertical movement in the event of breakage.
    Type: Grant
    Filed: October 29, 1985
    Date of Patent: February 3, 1987
    Inventor: Joseph L. Duncan