Patents by Inventor Donald Richard Wittkowski

Donald Richard Wittkowski 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).

  • Three-point hitch trailer
    Patent number: D512942
    Type: Grant
    Filed: May 17, 2004
    Date of Patent: December 20, 2005
    Assignee: AGri-Fab Incorporated
    Inventor: Donald Richard Wittkowski
  • Tandem axle trailer
    Patent number: D513717
    Type: Grant
    Filed: May 17, 2004
    Date of Patent: January 24, 2006
    Assignee: Agri-Fab Incorporated
    Inventor: Donald Richard Wittkowski
  • Tandem axle trailer
    Patent number: D522409
    Type: Grant
    Filed: October 26, 2005
    Date of Patent: June 6, 2006
    Assignee: Agri-Fab Inc.
    Inventor: Donald Richard Wittkowski
  • Poly cart
    Patent number: D535802
    Type: Grant
    Filed: June 14, 2004
    Date of Patent: January 23, 2007
    Assignee: Agri-Fab, Inc.
    Inventor: Donald Richard Wittkowski