Spicer Tandem Drive Axles Service Manual D__R440, 460, 480, D_R461, 462, 463, 521, 581, 601, 651, 652, 653 - Manual (Page 134)

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Theory of Operation
Power Flow and Torque Distribution
Torque Distribution with Lockout Disen-
gaged (Inter-axle Differential is Operating)
Torque (power flow) from the vehicle driveline is transmitted
to the input shaft and the inter-axle differential spider. At this
point, the differential distributes torque equally to both axles.
For the forward axle, torque is transmitted from the helical-
side gear to the pinion helical gear, drive pinion, ring gear,
wheel differential and axle shafts.
For the rear axle, torque is transmitted from the output shaft
side gear, through the output shaft to the inter-axle driveline,
to the drive pinion, ring gear, wheel differential and axle shafts.
1 - Input torque
2 - Drive is from differential through helical gears to forward gearing
3 - Drive is from differential through output shaft to rear gearing
4 - Inter-axle differential operating
5 - Lockout disengaged
1
2
3
4
5
Torque is transmitted to both axles without inter-axle differential action