Patents by Inventor Lyman H. Robertson

Lyman H. Robertson 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: 4034437
    Abstract: A normally pressure-free, failsafe, emergency door closer for use in hospitals, nursing homes or other locations where handicapped persons are housed, comprising an actuating mechanism triggered by a sensing device such as a smoke detector, a spring-loaded arm with a bumper on one end to engage the door and the other end of the arm rotatably attached to the wall adjacent to and above the door and free to rotate in a horizontal plane. The spring-loaded arm is retained in an open position by a vertical pin engaging the horizontal closer arm. The pin is mechanically linked to the armature of an electromagnet opposed by a coil spring. On signal from the sensing device the electromagnet releases the armature and the coil spring urges the pin upwards releasing the closer arm, the end of which engages the door and closes it.
    Type: Grant
    Filed: September 19, 1975
    Date of Patent: July 12, 1977
    Inventors: Lyman H. Robertson, John D. White