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:
Nov. 04, 1997
Filed:
Jun. 28, 1996
Kenneth P Liesener, Peoria, IL (US);
Kenneth F Golan, deceased, late of Pekin, IL (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
In machines such as hauling units having electro-hydraulic transmission controls, it is desirable to ensure that in the event of an electrical malfunction or power failure the transmission remains in one of its gear ratios. In the subject invention, a dependent latching system is provided in a transmission which in the event of an electrical malfunction latches the transmission in the existing gear ratio or a gear ratio within at least two gears ratios. This is accomplished by providing a master latch valve mechanism, a logic valve arrangement, and a latching shuttle valve to act in cooperation with an electrically controlled proportional valve and a hydraulic proportional valve that controls engagement of a plurality of hydraulically actuated clutches. The master latch valve mechanism directs pressurized fluid from a source of pressurized fluid through the logic valve to urge the latching shuttle valve to an open position. In the event of an electrical malfunction, the logic valve arrangement functions to sense the engaged hydraulically actuated clutches and controls the flow of pressurized fluid to respective ones of the latching shuttle valves to maintain the transmission in one of its operative gears.