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. 24, 1987
Filed:
Apr. 29, 1985
Reginald J Goss, Jr, Grafton, WI (US);
Gary S Jendrzejek, Milwaukee, WI (US);
The Oilgear Company, Milwaukee, WI (US);
Abstract
A constant speed hydraulic drive comprising a variable displacement hydraulic pump controlled to maintain a constant flow of hydraulic fluid even though a prime mover therefor is subject to speed variations. The constant flow rate delivered by the hydraulic pump is at a rate sufficient to drive a load hydraulic motor at a predetermined speed when the load hydraulic motor is subject to any given load. A pilot operated relief valve proportionally bleeds hydraulic fluid from ahead of the hydraulic motor in accordance with the speed and load of the hydraulic motor. And an electrical means provides a varying control signal to the pilot operated relief valve which is responsive to the total pulse error between those representative of motor speed and a predetermined speed to provide a first speed command signal greater than the predetermined speed, and a second speed command signal which modifies the first speed command signal by the difference in the actual speed from the first speed command signal, whereby the speed of the hydraulic motor is maintained at the predetermined speed.