Patents by Inventor Donald L. Shawkey

Donald L. Shawkey 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).

  • Extension trestle ladder
    Patent number: 4240522
    Abstract: A device for automatically locking the fly assembly of an extension trestle ladder in an extended or lowered adjustment position. The fly assembly is supported to prevent downward movement by a displaceable member which abuts a rung on the fly assembly along a portion of the length of the rung, which member is spring biased for automatic return to locking position.
    Type: Grant
    Filed: December 11, 1978
    Date of Patent: December 23, 1980
    Assignee: R. D. Werner Co., Inc.
    Inventors: Kenneth J. Spear, Donald L. Shawkey