Patents by Inventor Robert S. Hammond

Robert S. Hammond 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).

  • Sectional circular staircase
    Patent number: 4869034
    Abstract: A circular staircase in which each of the inside and outside stringers are constructed from a plurality of blocks strung together with cables. The blocks are substantially parallogram shaped with vertical ends which are bevelled to the inside. The blocks are strung end to end on tensioned cables. Shear pins inserted at the junction between adjacent blocks prevent relative vertical displacement between blocks. Spaced, horizontal treads join the inside and outside stringers together.
    Type: Grant
    Filed: November 7, 1988
    Date of Patent: September 26, 1989
    Inventor: Robert S. Hammond