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:
Apr. 28, 1981
Filed:
Nov. 08, 1978
Dietrich Jentsch, Ennepetal, DE;
Dorma-Baubeschlag GmbH & Co. KG, Ennepetal-Voerde, DE;
Abstract
A hydraulically controlled door closer in which a spring cooperating with a piston reciprocatable in a fluid filled bore urges a closer shaft operatively connected to the piston to a position in which a door connected to the closer shaft is closer. The spring is tensioned during turning of the closer shaft in a door opening direction and may be releasably held in the tensioned condition by an additional piston located between one end of the spring and the first-mentioned piston and provided with a first passage therethrough in which a one-way valve is located in a second passage which may be closed and opened by an electromagnetically operated valve.