In the "R" Range, the front carrier is locked and the front sun gear rotates clockwise. The front internal gear rotates counterclockwise. Therefore, the output axis rotates counterclockwise, and the vehicle moves backward.
Line pressure which is not applied to the shift valves A and B operates the low and reverse brake and the reverse clutch directly. Therefore, pilot pressure and shift solenoid valves A and B are not related to gear change. Line pressure is applied to the pressure regulator valve as well, and line pressure is kept higher than the valve of driving forward.