Patents by Inventor Siegfrid Graf

Siegfrid Graf 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: 3953054
    Abstract: A hand operated wheel-chair with a pair of main wheels rigidly connected with the frame-work of the chair, at least one of which is either motor or hand operated and at least one castor wheel being pivotally connected with the frame-work of the chair and at least one support wheel being rigidly connected with the frame-work. At least one castor wheel and support wheel are positioned on each side of a line extending between the support points of the main wheels and at a level above the ground surface to permit either the castor or the support wheels to be in contact with the ground surface depending on whether the vertical through the center of gravity is located on one or the other side of said line between the support points of the main wheels.
    Type: Grant
    Filed: March 18, 1974
    Date of Patent: April 27, 1976
    Assignee: Permobilstiftelsen
    Inventors: Per Udden, Siegfrid Graf, Bert Engman
  • Patent number: 3952822
    Abstract: An electrically powered wheel-chair for indoor and outdoor use comprising a pair of rear main wheels, which are non-pivotably connected with the frame-work of the chair, at least one of said wheels being driven by an electric motor. A steering wheel being rotatably connected with the frame-work of the wheel-chair and positioned in front of the main wheels, said steering wheel being asymmetrically located on one side of a longitudinal axis through the middle of the chair. A support wheel being positioned on the other side of said longitudinal axis relative to the steering wheel at such a level above a flat and horizontal ground surface that it will not touch this surface when the steering wheel directed straight ahead. The diameter of the support wheel is less than that of the steering wheel and the distance from the fore-most point of the steering wheel to a transverse axis through the centers of the main wheels is greater than the corresponding distance for the support wheel.
    Type: Grant
    Filed: March 18, 1974
    Date of Patent: April 27, 1976
    Assignee: Stiftelsen Teknisk Hjalp at Handikappade Permobilstiftelsen
    Inventors: Per Udden, Siegfrid Graf, Bert Engman