Patents by Inventor David L. Crawforth

David L. Crawforth 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).

  • Transit car door system and operation
    Patent number: 5226370
    Abstract: A computer assisted transit car door operating system for augmented automation of transit car door panel operation while providing safety provisions to restrain rail movement unless all passage doorways are closed. A programmable logic controller generates a sequence initiating (opening or closing) signal for a door panel; or, a manual input signal can be introduced for such purpose. The controller receives signals from a panel position sensor and a panel movement sensor to evaluate door panel status and generate status indication and panel movement signals. Automated control of door panel movement is selectively directed to a doorway, or doorways, at which an opening or closing problem is being encountered; that is, the exclusion of door panel movement signals to properly operated door panels.
    Type: Grant
    Filed: March 27, 1992
    Date of Patent: July 13, 1993
    Assignee: Morrison Knudsen Company
    Inventors: Frederick E. Templeton, Robert F. Carter, David L. Crawforth
  • Transit car door system and operation
    Patent number: 5119739
    Abstract: A computer assisted transit car door operating system for augmented automation of transit car door panel operation while providing safety provisions to restrain rail movement unless all passage doorways are closed. A programmable logic controller generates a sequence initiating (opening or closing) signal for a door panel; or, a manual input signal can be introduced for such purpose. The controller receives signals from a panel position sensor and a panel movement sensor to evaluate door panel status and generate status indication and panel movement signals. Automated control of door panel movement is selectively directed to a doorway, or doorways, at which an opening or closing problem is being encountered; that is, the exclusion of door panel movement signals to properly operated door panels.
    Type: Grant
    Filed: November 19, 1990
    Date of Patent: June 9, 1992
    Assignee: Morrison-Knudsen Company, Inc.
    Inventors: Frederick E. Templeton, Robert F. Carter, David L. Crawforth
  • Transit car door system and operation
    Patent number: 4981084
    Abstract: A computer assisted transit car door operating system for augmented automation of transit car door panel operation while providing safety provisions to restrain rail movement unless all passage doorways are closed. A programmable logic controller generates a sequence initiating (opening or closing) signal for a door panel; or, a manual input signal can be introduced for such purpose. The controller receives signals from a panel position sensor and a panel movement sensor to evaluate door panel status and generate status indication and panel movement signals. Automated control of door panel movement is selectively directed to a doorway, or doorways, at which an opening or closing problem is being encountered; that is, the exclusion of door panel movement signals to properly operated door panels.
    Type: Grant
    Filed: April 5, 1989
    Date of Patent: January 1, 1991
    Assignee: Morrison-Knudsen Company, Inc.
    Inventors: Frederick E. Templeton, Robert F. Carter, David L. Crawforth