For Strap Brakes Patents (Class 188/204A)
  • Patent number: 4168768
    Abstract: A hydraulic back-up system for use in combination with an equalizer beam of a drawworks brake system during the drilling of an oil and/or gas well bore for reducing the hazards in the event of failure of the drawworks braking system by automatically locking the equalizer beam in order that a single brake band of a two-brake band system will function for holding the load in an emergency situation.
    Type: Grant
    Filed: December 5, 1977
    Date of Patent: September 25, 1979
    Assignee: Loffland Brothers
    Inventors: Earl R. Johnson, Lesley G. Watkins