Patents by Inventor Robert H. Caldwell

Robert H. Caldwell 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: 4483084
    Abstract: A trencher machine for attachment to a tractor movably mounted hydraulically for up and down movement relative thereto, boom means for adjusting the depth of the cut in the soil, boom means pivotally mounted on a support means including cutting means thereon.
    Type: Grant
    Filed: June 9, 1982
    Date of Patent: November 20, 1984
    Assignee: Grizzly Corporations
    Inventors: Robert H. Caldwell, Randy J. Scott
  • Patent number: 4156466
    Abstract: An apparatus mounting on the main frame of a motorgrader for controlling grading and sloping of road shoulders and previously subgraded surfaces having a resilient suspension system for the moldboard depending from the main frame of the grader which is laterally spaced from the point of application of a control load by a universally-connected, double-acting hydraulic jack attached thereto; said moldboard being lifted against said resilient support relative to the main frame of the grader for grade control by a shoe, wheel or ski, which is mounted adjacent the one end thereof and arranged for sliding along a roadway or other previously graded surface as a horizontal reference, and tilted relative to the main frame for slope control by manipulation of the double-acting hydraulic jack controlled by a feedback controller which measures the error in actual moldboard tilt and compares it to a fixed vertical reference as determined by a pendulous sensor and corrects the same in establishing the desired slope to the
    Type: Grant
    Filed: January 20, 1978
    Date of Patent: May 29, 1979
    Assignee: Grizzly Corporation
    Inventor: Robert H. Caldwell