R Range
In "R" range, the reverse clutch and the low & reverse brake are thrown into engagement. The engaged reverse clutch allows the front sun gear to rotate, while the engaged low & reverse brake allows the low clutch drum to be interlocked with the transmission case.
The rotation of the input shaft causes the front sun gear to rotate, which in turn causes the front pinion gears to rotate in the reverse direction. Thus, the rotation torque of the input shaft is transmitted to the front internal gear.
At this time, the rotation speed transmitted to the front internal gear is reduced by the front sun gear and the front pinion gears.
The one-way clutch produces no effect because the low & reverse brake is in engagement.
In this range, since the power transmission is made without influence of the one-way clutch, the back driving force from the reduction drive shaft is transmitted to the input shaft, thus the braking effect of the engine being available.