Abstract: A multiple stage automatic transmission includes a main transmission mechanism, a sub-transmission mechanism connected with the main transmission mechanism to for introduction of a torque therefrom, and a frictional element connected with the sub-transmission. The engaging force of the frictional element is changed at least by two steps in accordance with a shift mode without changing a hydraulic pressure applied for actuating the frictional element. A shift shock, therefore, can be obviated.

Abstract: An automatic transmission control system couples frictional coupling element, such as a low reverse brake, so that the frictional coupling element provides different torque transmissive capacities in a reverse gear and a first gear in which engine braking is available. The system includes a pressure regulator which regulates a coupling pressure, by which the frictional coupling element is coupled and which is controlled and gradually supplied to the frictional coupling element, during a shifting of the automatic transmission to a reverse gear. The pressure regulator is disabled from regulating the coupling pressure in the reverse gear.

Abstract: An automatic transmission control system includes a hydraulic circuit for controlling coupling pressure supplied to frictional coupling elements of the automatic transmission, which are selectively coupled and uncoupled so as to shift the automatic transmission into desired gears. The hydraulic circuit has a solenoid valve, for regulating a principal hydraulic pressure to provide a control pressure in accordance with vehicle driving conditions. The coupling pressure, supplied to a frictional coupling element, is regulated by a regulating valve in accordance with a control pressure level, and during shifting of the automatic transmission, is supplied through an accumulator whose back pressure is controlled in accordance with the control pressure by a control valve.

Abstract: An automatic transmission has a hydraulic circuit which controls supply of engaging pressures to friction coupling elements. The hydraulic circuit has a first hydraulic passage having a hydraulic pressure control valve including an accumulator, a second hydraulic passage which is provided in parallel to the first hydraulic passage and is provided with an electrically controlled hydraulic pressure control valve, and a shift valve which selectively connects a predetermined friction coupling element to the first hydraulic passage or the second hydraulic passage.

Abstract: The control system for an automatic transmission shifts the main transmission simultaneously with the auxiliary transmission at the time of a particular shift. At this time, a target gear ratio progress value of the auxiliary transmission is set for a gear ratio progress value indicative of a shift progress state of the main transmission. The main transmission is arranged so as to finish the shift control within a given target period of time, and the auxiliary transmission is arranged to implement the shift control by the feedback control so as to follow the target gear ratio progress value. The shift control of the auxiliary transmission is corrected by the learning control on the basis of a deviation between the target gear ratio progress value and the actual gear ratio progress value.

Abstract: A control system for an engine with an automatic transmission, including an output reducing system for reducing an output of the engine by a predetermined quantity in a speed change operation of the automatic transmission, so as to suppress a speed change shock generated in the speed change operation; and an output reduction control system for controlling a start timing of operation of the output reducing system so as to make a timing when output reduction of the engine is completed by the output reducing system coincide with a start timing of an actual gear shift operation of the automatic transmission. Accordingly, the engine output is reduced in the speed change operation of the automatic transmission, and the speed change shock generated in the speed change operation can be greatly suppressed by making the timing when the output reduction of the engine is completed coincide with the start timing of the actual gear shift operation of the automatic transmission.

Abstract: A control system for an automatic transmission for a vehicle includes a vehicle speed sensor, a throttle opening sensor, and a controller. The controller causes the automatic transmission to upshift on the basis of a first upshift line when the temperature of transmission oil is not lower than a predetermined value and on the basis of a second upshift line when the temperature of transmission oil is lower than the predetermined value. The first upshift line is set so that the automatic transmission is caused to upshift substantially irrespective of the throttle opening when the vehicle speed exceeds a first predetermined speed in a kick-down range and the second upshift line being set so that the automatic transmission is caused to upshift substantially irrespective of the throttle opening when the vehicle speed exceeds a second predetermined speed in said kick-down range. The second predetermined speed is lower than the first predetermined speed.

Abstract: A control apparatus for an automatic transmission is disclosed which has shift valves to which a kickdown pressure, governor pressure corresponding to vehicle velocity and throttle pressure are applied, wherein the shift valves are changed over in dependence upon an equilibrium. The apparatus controls the application of the kickdown pressure to the shift valves. When the transmission speed detected during the kickdown operation is a relatively lower speed and vehicle velocity is rising, the kickdown pressure is applied within a first velocity region (Z1 or Z4) on a lower velocity side of a first vehicle velocity (V.sub.U2I or V.sub.U3I) which is less than an engine overrun point (V.sub.o1 or V.sub.o2); it is not applied within a second velocity region (Z2 or Z5) which is set from the first vehicle velocity to a second vehicle velocity which exceeds the engine overrun point (V.sub.o1 or V.sub.o2); and it is applied within a third velocity region (Z3 or Z6) which exceeds the second vehicle velocity.