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. 06, 1993
Filed:
Jul. 09, 1992
Peter L Falck, Waterloo, IA (US);
Dennis L Jeffries, Waterloo, IA (US);
David E Brandon, Waterloo, IA (US);
Deere & Company, Moline, IL (US);
Abstract
The hydraulically operated brake and clutch elements (controlled by proportional control valves) of a vehicle powershift transmission have fill pressures which are calibrated by a method wherein the output shaft of the transmission is disconnected from the vehicle drive shaft so that the transmission output shaft is free to rotate and certain ones of the plurality of the control elements other than the control element being calibrated are fully pressurized in order to prevent rotation of a part of the control element being calibrated. The engine is run at a predetermined speed and the pressure applied to the control element being calibrated is gradually increased while engine speed is monitored. When the monitored engine speed changes by predetermined amount, a value is saved corresponding to the calibration pressure. The transmission is automatically shifted to neutral if vehicle motion is sensed. The volume of hydraulic fluid required to initially engage the control element may be calibrated in a similar manner.