Abstract: An electro-hydraulic park control system includes a park piston and a park control valve disposed in a valve body of a transmission of a vehicle and configured to control a supply of hydraulic fluid pressure to control the park piston and to operate such that (i) no single element failure of the transmission will cause the transmission to shift from a park state to a non-park state or (ii) to shift from a drive, reverse, or neutral state to the park state, (iii) the transmission is able to remain in the non-park state and remain in or transition to the neutral state when a controller of the transmission is malfunctioning while the transmission is operating in the drive, reverse, and neutral states, and (iv) the transmission is able to quickly transition to the park state while an engine/motor driven pump of the transmission is off or not running.

Abstract: A method of determining shift points in a step gear transmission system to maximize fuel economy is disclosed. In operation, the method uses fuel economy data from a first gear ratio to determine a first series of constant fuel consumption curves for the first gear ratio. The method then uses fuel economy data from a second gear ratio to determine a second series of constant fuel consumption curves for the second gear ratio. Next, the method determines points of intersection where a respective fuel consumption curve for the first gear ratio intersects its corresponding fuel consumption curve for the second gear ratio. A decision curve is generated from the points of intersection.

Abstract: A shift control valve has a valve body in which is rotatably disposed a flow directing plate. Pressurized "drive" fluid is supplied to a control passage in the plate. The control passage communicates with a plurality of radial passages extending therefrom. Circumferential and axial passages communicating with the radial passages selectively direct fluid flow, through the valve body, from the control feed passage to friction device control passages to establish the engagement of friction devices. A plurality of exhaust passages control fluid flow for the disengagement of the friction devices. Supplemental axial feed passages are available to supply fluid pressure for the friction devices during selected ratios other than "drive".

Abstract: A hydraulic control system for an automatic transmission, the system including: a fluid pump; a proportional control valve for reducing a hydraulic pressure in accordance with a vehicle speed; a valve body including a line pressure inlet port for receiving the hydraulic pressure compressed by a fluid pump, a line pressure outlet port for flowing out the hydraulic pressure to be used as a driving pressure in a "D" range; a reverse pressure port for flowing out the hydraulic pressure to be used as the driving pressure in an "R" range; and a first, a second, a third and a fourth speed ports for receiving the hydraulic pressure from the line pressure outlet port and for flowing out the hydraulic pressure to shift a speed stage in accordance with a vehicle speed; a manual valve rotatably disposed in the valve body and rotates in accordance with a movement of a shift lever; and a shift control valve rotatably disposed in a same concentric axis with said manual valve in the valve body; the manual valve including a n

Abstract: A transmission has a manual selector valve which is reciprocally and rotatably mounted in a valve body and operable in a conventional "H" shift pattern to permit selection of first through fifth forward drive conditions, a neutral condition and a reverse drive condition in a planetary transmission. The selector valve has a line pressure chamber formed thereon that remains in fluid communication with a line feed passage in the valve body throughout the "H" pattern. This line pressure chamber is selectively alignable with respective clutch and brake apply passages formed in the valve body to control the flow of pressurized oil for the engagement of respective clutches and brakes. A plurality of exhaust chambers formed therein are also selectively connectible with the clutch and brake apply passages to control disengagement of the respective clutches and brakes not required for the selected drive condition.

Abstract: A hydraulic control has valves for controlling the drive range selection and ratio interchange in a power transmission including a selector valve, a shift valve and a coast control valve. Each of these valves has a rotary spool distribution member for directing pressurized fluid to passages in a housing from which the fluid is delivered to the proper transmission mechanisms. The control simultaneously exhausts other transmission mechanisms.