Spicer Tandem Drive Axles Service Manual D170, D190, and D590 Series - Manual (Page 85)

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Theory of Operation
Power Divider Operation (Power Flow and Torque Distribution)
In operation, the power divider accepts torque from the
vehicle driveline and distributes it equally to the two axles.
This assembly is of the two-gear design consisting of an
input shaft, inter-axle differential, output shaft and two
constant-mesh helical gears.
The inter-axle differential compensates for minor variations
in speed between the two axles, the same way the wheel
differential works between the two wheels of a single drive
axle. This unit also acts as a central point in distribution of
torque to the two axles.
The power divider also includes a driver-controlled, air-
operated lockout. When lockout is engaged, it mechanically
prevents inter-axle differentiation for better performance
under poor traction conditions.
With Lockout Engaged
(Inter-Axle Differential is Operating)
1 - Input torque
2 - Lockout disengaged
3 - Forward axle torque is transmitted from the helical side
gear through the pinion helical gear, drive pinion, ring gear,
wheel differential and axle shafts.
4 - Rear axle torque is transmitted from the output shaft side
gear through the output shaft, inter-axle driveline, drive
pinion, ring gear, wheel differential and axle shafts.
5 - Input torque (power flow) from the vehicle driveline is
transmitted to the input shaft and the inter-axle differential
spider. The differential distributes torque equally to both
axles.
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2
3
5
4
Theo
ry of Operation