Patents by Inventor David L. Hoffman

David L. Hoffman 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).

  • Magnetic friction device
    Patent number: 4544048
    Abstract: A magnetic friction device for permitting one machine member to be moved relative to another by applying a predetermined force and for holding one member in a fixed position when the force is discontinued. One member is magnetically susceptible and has a smooth surface interfacing with but slightly spaced from a surface on the other member. The other member's surface has one or more recesses in which there are magnetic disks of a polymer impregnated with magnetic particles. The disks are attracted to the smooth surface to produce a design controlled predetermined frictional force.
    Type: Grant
    Filed: July 15, 1983
    Date of Patent: October 1, 1985
    Assignee: General Electric Company
    Inventor: David L. Hoffman
  • Magnetic friction device
    Patent number: 4417356
    Abstract: A magnetic friction device for permitting one machine member to be moved relative to another by applying a predetermined force and for holding one member in a fixed position when the force is discontinued. One member is magnetically susceptible and has a smooth surface interfacing with but slightly spaced from a surface on the other member. Said other member's surface has one or more recesses in which there are magnetic disks of a polymer impregnated with magnetic particles. The disks are attracted to the smooth surface to produce a design controlled predetermined frictional force.
    Type: Grant
    Filed: May 14, 1981
    Date of Patent: November 22, 1983
    Assignee: General Electric Company
    Inventor: David L. Hoffman