Patents by Inventor David Roth Williams

David Roth Williams 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).

  • Refrigerated semitrailer truck for long and local deliveries
    Patent number: 4060400
    Abstract: A refrigerated semitrailer truck for both long and local delivery of frozen foods in a hot environment is disclosed which utilizes both a liquid nitrogen unit and a mechanical refrigeration unit with an automatic control system. The system automatically turns the liquid nitrogen off when the temperature is above 30.degree. F., below -10.degree. F., or when an access door to the insulated truck is open. The liquid nitrogen also operates as a standby unit at all temperatures above -10.degree. F. in the event of a malfunction of the mechanical unit.
    Type: Grant
    Filed: August 22, 1975
    Date of Patent: November 29, 1977
    Assignee: Henry L. Franke
    Inventor: David Roth Williams