Patents by Inventor Charles A. McDonnell

Charles A. McDonnell 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: 5743355
    Abstract: A retractable ladder having a low coefficient of friction plastic bushing is received within a coupling that joins a ladder rung to the associated longitudinal stile. The coupling is press fitted to the bushing, compressing a portion of the bushing against the stile, slightly deforming the adjoining portion of the stile to lock the assembly together. A latch having an inwardly sloping surface locks the ladder stiles in an extended condition and cannot be withdrawn to retract the ladder when the ladder is supporting a normal load. Dampers having orifices also are mounted in some or all of the hollow stiles to regulate the flow of air from the retracting stiles and, in this way to retard the velocity with which the ladder retracts to a predetermined, safe value.
    Type: Grant
    Filed: July 31, 1996
    Date of Patent: April 28, 1998
    Inventors: Charles A. McDonnell, Leonard Silverman