The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 27, 1981
Filed:
Sep. 07, 1979
George C Balbach, Lake Forest, IL (US);
Robert J Peterman, Cedarburg, WI (US);
Arthur Smith Industries, Inc., Milwaukee, WI (US);
Abstract
An automatic door operator for opening and closing a door such as a cold storage door which is mounted in a frame for sliding movement in a vertical plane has a hydraulic control system which includes an electric motor for rotating a reversible hydraulic pump, an electric control circuit which activates the electric motor to rotate the pump in the appropriate direction, and a reversible rotary hydraulic motor driven by the pump to rotate a chain drive which draws the door to its open and closed positions. The hydraulic control system also includes a means for cushioning the rapid start and stop of the door to provide smooth operation which includes a pair of check valves disposed in the control system such that one check valve is on either side of the hydraulic pump, and a first set of pressure relief valves disposed in the control system on either side of the pump between the pump and the check valves, and a second set of pressure relief valves between the check valves and the hydraulic motor. The check valves provide a locking mechanism for the door so that when the flow of hydraulic fluid from the pump stops, the door is locked in its open or closed position.