Figure 9.9. Reduction Gearbox.
The second stage of reduction is contained in the reduction gearbox front case. The first
stage planet carrier is attached to the second stage sun gear by a flexible coupling which also dampens
any vibrations between the two rotating masses. The second stage sun gear drives five planet gears in
the second stage carrier. A second stage ring gear is fixed by splines to the reduction gearbox front case
and secured by three bolted retaining plates. The second stage carrier is in turn splined to the propeller
shaft and secured by a retaining nut and shroud washer.
The accessories located on the reduction gearbox front case are driven by a bevel drive gear,
mounted on the propeller shaft behind the thrust bearing assembly. Propeller thrust loads are absorbed
by a flanged ball bearing located in the front face of the reduction gearbox centerbore. The thrust
bearing cover is secured to the front of the reduction gearbox, and it has a removable oil seal retaining
ring for replacement of the oil seal.