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:
Sep. 25, 1990
Filed:
Mar. 20, 1989
Herman P Schutten, Bayside, WI (US);
Dwight B Stephenson, Savage, MN (US);
Donald M Haarstad, Chaska, MN (US);
Eaton Corporation, Cleveland, OH (US);
Abstract
An open-center fluid controller (15) is disclosed for controlling the flow of fluid to a steering cylinder (25). The controller includes a fluid meter (29) and valving arrangement (27), including a valve spool (43) and a sleeve (45), which define a main fluid path. The main path includes a fixed flow control orifice (86), a variable flow control orifice (87), the fluid meter (29), and a variable flow control orifice (89). In accordance with the invention, the spool and sleeve define an amplification fluid path (101), including a variable amplification orifice (99), in parallel with the main fluid path, and disposed to amplify the flow of fluid through the meter (29). In order to facilitate manual steering, the amplification orifice (99) reaches its maximum flow area when the spool and sleeve are in a normal operating position (FIG. 6). The amplification orifice then decreases and closes as the displacement between the spool and sleeve reach a maximum displacement (FIG. 7). As a result, the amplification fluid path (101) is closed at maximum valve displacement, thus making it possible to manually steer the vehicle.