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:
Jul. 12, 1988
Filed:
Oct. 29, 1986
Wilhelm Appel, Ulm-Donaustetten, DE;
Hydromatik GmbH, , DE;
Abstract
A control circuit for a reversible hydrostatic transmission including a reversible pump having first and second working lines, and a control member having forward and reverse positions to normally direct a working fluid through the first and second working lines respectively. A servo-motor has forward and reverse positions to hold the pump control member in either its forward or reverse positions, and a first subcircuit is provided to conduct a control fluid to the servo motor to hold that motor in either its first or second positions. This first subcircuit includes a pair of piston and cylinder units, with each of these units having a control pressure chamber and a working pressure chamber. A second subcircuit is provided to conduct the working fluid from the working lines to the working pressure chamber of either the first or second piston cylinder unit, and this second subcircuit includes a change over valve to insure that the working pressure is maintained in the appropriate working pressure chamber even if there is a sudden reversal in the load on the pump.