Quoting Removed, click Modern View to see
Don't know for sure yet :oops: The reduction gear shifter is the sliding collar that is splined to the output shaft and it shifts the same way the PTO shifts.
- When shfted forward it engages the transmission output shaft directly via a set of dog clutch teeth locking the gearbox output shaft to the transmission output shaft in a 1:1 drive. The planetary eduction gears are not engaged and simply spin free.
- When shifted rearward it disengages the dog clutch teeth from the output shaft and engages the external gear with the sun gears. That produces a 3.5:1 reduction on the transmission output speed.
The OEM shift rail for the PTO has to be rolled to the side similar to the the NAA to get clearance for the gearbox and I've already munged the PTO housing shown in the pictures to do that. Building a modified linkage is one of the remaining efforts. Then a second linkage gets added, probably on the right side, for shifting the reduction gearbox. It's only been a bit over 3 years since I first embarked on this project so things are moving right along :roll:
PS> Any resemblance to the Howard planetary reduction gearbox used on the NAA and later tractors is pure coincidence.....