Patents by Inventor Hendrikus Kramer

Hendrikus Kramer 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: 4259992
    Abstract: A flexible pipe section for the transportation of a mixture of water and solid material, such as pieces of stone, rock, metal and the like objects having sharp points and/or edges and/or projections offering a high resistance to wear and damage in that the wall of the pipe section lying between couplings at the ends of said pipe section, in order to lengthen its life, comprises a row of abrasion-resisting annular members spaced from each other and extending substantially in between the inner and outer surfaces of the wall of the pipe section and inclined at a sharp angle with the longitudinal axis of said pipe section, a tubular cover of elastic material on the pipe section including said wall, said cover having at least one insert serving to prevent as much as possible tension occurring in the layers of rubber or elastic material connecting said members.
    Type: Grant
    Filed: September 10, 1979
    Date of Patent: April 7, 1981
    Assignee: Vredestein N. V.
    Inventor: Hendrikus Kramer