Patents by Inventor Douglas H. Rigerman

Douglas H. Rigerman 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).

  • Manway lift assist
    Patent number: 5038520
    Abstract: The invention relates to an improved balancing aid for a pivotally mounted cover for a manhole comprising means for hinging the cover relative to the manhole so the cover may be rotated about the hinge to expose and cover the manhole; and a spring retaining means comprising a rod pivotally secured to the cover, said rod being at least partially encased by a housing, said housing containing a compression spring means which is compressed when the cover is closed; wherein the improvement comprises securing the spring retaining means by attachment means which may be removed only after the spring means is first removed.
    Type: Grant
    Filed: November 1, 1990
    Date of Patent: August 13, 1991
    Assignee: The Pfaudler Companies, Inc.
    Inventors: Franklyn J. Amorese, Robert R. Loomis, Douglas H. Rigerman