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:
Feb. 03, 2015
Filed:
Jan. 04, 2013
Zf Friedrichshafen Ag, Friedrichshafen, DE;
Thilo Schmidt, Meckenbeuren, DE;
Markus Herrmann, Scheidegg, DE;
Hans-Joachim Martin, Kressbronn, DE;
ZF Friedrichshafen AG, Friedrichshafen, DE;
Abstract
A hydraulic shifting device for an automatic transmission for engaging and disengaging a parking lock. The shifting device comprises a parking lock cylinder () for actuating the parking lock, and a parking lock valve () which, for hydraulic control of the parking lock cylinder (), can be switched to at least first and second shift positions. In this case the hydraulic shifting device comprises a further parking lock valve (), and the two parking lock valves () and the parking lock cylinder () are designed and connected with one another in such manner that the parking lock can only be disengaged by pressurizing the parking lock cylinder () if the two parking lock valves () are each switched to a particular shift position.