Hitachi ZW180 Technical Manual page 328

Forward 4th Speed
In case of forward 4th speed, the forward clutch is
connected to the 4th speed part of 3rd / 4th speed
clutch. The torque converter transmits torque to F
hub gear (4) which is meshed with input gear (1).
Torque from F hub gear (4) is transmitted to 4th
speed hub gear (12) through F-R gear (3) and idler
gear (7).
COMPONENT OPERATION / Drive Unit
1
4
Forward
Clutch
3
7
In addition, torque is transmitted from 4th hub gear
(12) to high-range gear (14), and finally to output
gear (15).
Input
Output
Power Flow: Forward 4th Speed
T3-9-22
3rd / 4th
Speed Clutch
12
14
15
T4GC-03-09-021