Patents by Inventor Donald S. Fraser

Donald S. Fraser 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).

  • Grinders
    Patent number: 4153209
    Abstract: A grinder for material wherein a series of hollow balls is entrained for rotational movement between an upper ring and a lower ring, the rings being relatively rotatable about a control axis, and the balls being rotatable between the rings, and the material for grinding being fed into a zone between the balls and rings. The contact zone between the upper ring and each ball is defined by two annular lips and is substantially less than the contact zone between the lower ring and each ball.
    Type: Grant
    Filed: September 1, 1977
    Date of Patent: May 8, 1979
    Assignee: Babcock and Wilcox of Africa
    Inventor: Donald S. Fraser