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:
Dec. 09, 2003
Filed:
May. 21, 2002
Herbert Coenen, Konigswinter, DE;
John Sayer, Shropshire, GB;
GKN Walterscheid GmbH, , DE;
Abstract
A hydraulic lift device for an attaching device of a tractor which has a hydraulic pressure supply device and a hydraulic tank, comprising for each of two lower steering arms, a double acting hydraulic cylinder having a cylinder housing, a piston rod, a piston with a piston-end piston area and a piston rod-end piston area, as well as a piston-end cylinder chamber and a piston rod-end cylinder chamber. The device further comprises a first switching valve, which has at least three switching positions and four ports. The first port represents a connection to the pressure supply device. The second port represents the connection to the hydraulic tank. The third port represents the connection to the piston-end cylinder chamber of the first hydraulic cylinder and the fourth port represents the connection to the piston rod-end cylinder chamber of the second hydraulic chamber. The piston rod-end cylinder chamber of the first hydraulic cylinder is connected via a line to the piston-end cylinder chamber of the second hydraulic cylinder. The piston rod-end piston area of the first hydraulic cylinder and the piston-end piston area of the second hydraulic cylinder have the same size or a predetermined size relationship to each other.