Patents by Inventor Robert Arthur Letts

Robert Arthur Letts 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).

  • Method of making a dimensionally stable commutator
    Patent number: 4056882
    Abstract: This invention describes a method of making a commutator, for a high speed electric machine, (1) embedding a number of conductive bars in insulating plastics material to form a moulded commutator (2) the moulded commutator defining at least one annular seat (3) placing a ring of high tensile material on the seat whereby to stress the ring in tension and thereby apply a radially inward load to each bar which is greater than the centrifugal force on the bar at maximum running speed. The invention also includes a commutator made by this method.
    Type: Grant
    Filed: June 7, 1976
    Date of Patent: November 8, 1977
    Assignee: Airscrew Howden Limited
    Inventor: Robert Arthur Letts