Patents by Inventor David A. Engstrom

David A. Engstrom 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: 4691428
    Abstract: Disclosed is a spanner wrench for and method of removing a torque-locked torsion spring from a winding cone. The wrench retrieves and engages the terminal end of the spring to apply both a radially outwardly directed force to such terminal end of the spring while simultaneously applying a tangentially-directed force which is counter to the torque lock to remove the spring from the cone without damage to the cone. In its preferred form the wrench is adjustable so as to be able to accommodate spring and cone assemblies of widely varying diameters.
    Type: Grant
    Filed: April 14, 1986
    Date of Patent: September 8, 1987
    Inventor: David A. Engstrom