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. 09, 2002
Filed:
Jun. 30, 2000
Yong Cheol Jeon, Incheon, KR;
Daewoo Heavy Industries Ltd., Incheon, KR;
Abstract
A semi-automatic power shift transmission for use in a forklift truck includes a manual shift lever with first and second gear positions, a hydraulically shifted transmission gear mechanism operable in one of first and second gear ratios corresponding to the first and second gear positions, a plurality of solenoids for, when energized, causing the transmission gear mechanism to be either up-shifted from the first to the second gear ratio or down-shifted from the second to the first gear ratio, a transmission speed sensor for detecting the output speed of the transmission gear mechanism to generate a transmission speed signal, an engine speed sensor for picking up the speed of a vehicle engine to produce an engine speed signal, a steering wheel angle sensor for measuring the steering wheel angle to issue a wheel angle signal, and a transmission control unit responsive to the transmission speed signal, the engine speed signal and the wheel angle signal for selectively energizing the solenoids to thereby carry out the up-shifting operation in the event that a load ratio calculated by dividing the transmission speed with the engine speed is greater than a preselected reference load ratio, with the transmission speed larger than a preselected reference up-shift speed and the steering wheel angle smaller than a preselected reference angle. Also disclosed is a novel shift control method of the power shift transmission noted above.