Abstract: A control system of an automatic transmission includes a torque converter, a lock-up clutch for directly connecting input and output members of the torque converter, a pressure control valve which changes a hydraulic pressure to control an engaging force of the lock-up clutch, and a pressure regulator, disposed in an engaging passage, which supplies hydraulic pressure to engage a frictional element. The pressure regulator adjusts a primary pressure and produces an output hydraulic pressure corresponding to a control pressure introduced into a control port of the pressure regulator. A control pressure supply device is provided for introducing the control pressure, controlled by the pressure control valve, into the control port of the pressure regulator. The number of parts can be reduced without producing any inconvenience.

Abstract: An automatic transmission control system for selectively locking and unlocking a plurality of frictional coupling elements is provided within an automatic transmission so as to place the automatic transmission into one of various possible gears. The control locks a specific one of the frictional coupling elements with locking pressure when the automatic transmission performs a specific gear shift and unlocks it by reducing the locking pressure when causing it to perform, an opposite gear shift reverse to the specific gear shift. The locking pressure is increased by way of a relatively high level of shelf pressure during the specific gear shift and reduced by way of a relatively low level of shelf pressure during the opposite gear shift.

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: In a control system for an automatic transmission, when successive order signals are emitted so that shift changes are accomplished over multiple shift stages, a shift change ordered by an initial order signal is carried out before a shift change ordered by a last order signal is carried out if a shift gear mechanism has already started its operation. However, a shift change ordered by a last order signal is carried out, without shift changes ordered by an initial order signal and intermediate order signals being carried out, if the shift gear mechanism has not started its operation.

Abstract: An automatic transmission includes a first transmission mechanism having a first shaft connectable to an output shaft of an engine, a second transmission mechanism associated with the first transmission mechanism, and having a second shaft in parallel with the first shaft, the second transmission mechanism being adapted for changing the torque speed of the first shaft, a hydraulic housing for accommodating a hydraulic control device for the second transmission mechanism, the second hydraulic housing being arranged above the second transmission mechanism, and an axis of the second shaft being positioned on either the same horizontal plane as an axis of the first shaft or a horizontal plane above the axis of the first shaft.

Abstract: A hydraulic control system for controlling an automatic transmission includes a regulating valve which reduces a line pressure in accordance with a control pressure, provided in accordance with vehicle driving conditions, to provide a coupling pressure for coupling a specific one of frictional coupling elements of the automatic transmission. The regulating valve is enabled to provide the coupling pressure independently from the control pressure when a coupling pressure for another frictional coupling element higher than a specified level.

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.