Patents by Inventor David L. Trowbridge

David L. Trowbridge 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: 6786170
    Abstract: In accordance with the present invention there is provided a lifting device for a boat, the lifting device including a first platform and a plurality of linkage members, the plurality of linkage members configured to form at least two four-bar linkage assemblies, each having a first end pivotally attached to the platform and a second end pivotally attached to a boat. The lifting device further including at least one hydraulic cylinder, the cylinder having a first end and second end, the first end being pivotally affixed to the structure of a boat and the second end pivotally attached to at least one linkage member, and a fluid device in communication with the hydraulic cylinder. A load sharing member connects the two four-bar linkage assemblies and prevents uneven or tilted motion of the platform.
    Type: Grant
    Filed: April 16, 2003
    Date of Patent: September 7, 2004
    Inventor: David L. Trowbridge
  • Publication number: 20030192466
    Abstract: In accordance with the present invention there is provided a lifting device for a boat, the lifting device including a first platform and a plurality of linkage members, the plurality of linkage members configured to form at least two four-bar linkage assemblies, each having a first end pivotally attached to the platform and a second end pivotally attached to a boat. The lifting device further including at least one hydraulic cylinder, the cylinder having a first end and second end, the first end being pivotally affixed to the structure of a boat and the second end pivotally attached to at least one linkage member, and a fluid device in communication with the hydraulic cylinder. A load sharing member connects the two four-bar linkage assemblies and prevents uneven or tilted motion of the platform.
    Type: Application
    Filed: April 16, 2003
    Publication date: October 16, 2003
    Inventor: David L. Trowbridge
  • Patent number: 4084132
    Abstract: A method and apparatus for recording directly group delay measurement of a system under temperature and stress tests employing a modulated carrier frequency swept over an S or X-band of interest and applied through a reference path and a test path to separate detectors for group delay measurement using a power divider, e.g., a directional coupler or a hybrid-T junction. A phase comparator is initially balanced, and then the modulated carrier is swept in frequency over the band of interest for different conditions of temperature and/or mechanical stress to obtain a family of characteristic group-delay curves for the system under test.
    Type: Grant
    Filed: November 24, 1976
    Date of Patent: April 11, 1978
    Inventors: James C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, David L. Trowbridge
  • Patent number: 4055810
    Abstract: An X-band traveling wave maser of the folded-comb type is provided with two figure-eight coils for gain and bandwidth control. One figure-eight coil covers the full length of the comb structure for bandwidth adjustment of an external magnetic field. The other figure-eight coil covers a central half of the comb structure for independent gain adjustment of the external magnetic field. The half of each figure-eight coil at the turn around end of the comb structure is oriented to aid the external magnetic field, and the half of each figure-eight coil at the input-output end of the comb structure is oriented to buck the external magnetic field. The maser is pumped in the push-push mode with two different frequencies.
    Type: Grant
    Filed: July 26, 1976
    Date of Patent: October 25, 1977
    Inventors: James C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, David L. Trowbridge