Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2008-10-24
2011-12-06
Estremsky, Sherry (Department: 3655)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
Reexamination Certificate
active
08070636
ABSTRACT:
An electrohydraulic control device (1) of an 8-speed transmission having several electrically controllable pressure control valves (6-12) for hydraulically actuating five switching elements (A-E) and an electric gear control unit via which different operating states of the transmission may be adjusted. Three of the switching elements are connected in the force flow of the transmission for representing a gear ratio (“1” to “R”) of the transmission. When the gear control unit is de-activated and the power supply to the solenoid valve and pressure control valves is interrupted, and when the transmission is in the operating state, in which a gear ratio (“1”; “2”; “3”; “4”; “5”; “6”; “7”; “8”; “R”) is engaged, a predefined emergency transmission (“6”; “R”) is represented by three simultaneously hydraulically connected switching elements (C, D, E, A, B, D).
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Gierer Georg
Schmidt Thilo
Davis & Bujold P.L.L.C.
Estremsky Sherry
ZF Friedrichshafen AG
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