Patents by Inventor Harry J. Friedenreich

Harry J. Friedenreich 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).

  • Releasable hoistway door safety interlock
    Patent number: 4469200
    Abstract: To prevent passengers in an elevator from opening the hoistway door when the car is well above the floor, a rotatable arm is located below the car and engages the hall door to prevent it from being opened. This arm may be reached from the floor, by opening the hoistway doors slightly, and rotated to disengage it from the door, which may then be fully opened.
    Type: Grant
    Filed: October 29, 1981
    Date of Patent: September 4, 1984
    Assignee: Otis Elevator Company
    Inventors: Robert W. Young, Harry J. Friedenreich