In 4th Gear

Hydraulic pressure is applied to the 4th clutch, then the 4th clutch engages the mainshaft 4th gear with the mainshaft.
The mainshaft 4th gear drives the countershaft 4th gear and the countershaft.
Power is transmitted to the final drive gear, which in turn drives the final driven gear and the transfer drive gear.
The transfer output shaft drives the transfer hypoid drive gear/shaft and the transfer output shaft (hypoid gear).
Hydraulic pressure is also applied to the 1st clutch, but since the rotation speed of 4th gear exceeds that of 1st gear, power from 1st gear is cut off at the one-way clutch.

NOTE: The graphic shows the 4WD transmission; the 2WD transmission does not have the transfer mechanism.

Fig 1: Identifying A/T Power Flow Diagram (4th Gear)

Courtesy of AMERICAN HONDA MOTOR CO., INC.