Patents by Inventor Jan Piet t. Sijthoff

Jan Piet t. Sijthoff 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 and apparatus for breaking up lumps of stone from a subaqueous soil
    Patent number: 4150502
    Abstract: When breaking up lumps of stone from a subaqueous stony ground, the lumps are loosened by means of at least one chisel inserted into the ground and being moved along the ground surface. In order to break up lumps of stone by low power and to main a predetermined size of the loosened lumps of stone suitable for being lifted by a suction dredger system, the structure of the top layer of the stony ground is disturbed by inserting displacers from above into the ground at places distributed over the ground surface.
    Type: Grant
    Filed: December 16, 1976
    Date of Patent: April 24, 1979
    Assignees: Ballast-Nedam Groep N.V., Amsterdamse Ballast Bagger en Grond, B.V. en Scheepswerf en Machinefabrick "de liesbosch" B.V.
    Inventor: Jan Piet t. Sijthoff