Spicer Single Drive Axles Service Manual: 34DS, 34RS, 38DS, 38RS, DS340, RS340, DS380, RS380, DS400, RS400, DS3 - Manual (Page 8)

General Information
5
Power Flow and Torque Distribution
Spicer tandem drive axles described in this publication are single reduction units designed primarily for highway or turnpike.
They are also for a variety of other applications. This type of axle provides a vehicle with superior load carrying and roadability
characteristics by dividing its work between two axles. The complete tandem assembly consists of two axles coupled by a power
divider.
Power Divider
In operation, the power divider accepts the torque from the vehicle driveline and distributes it equally to the two axles. This as-
sembly 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 axle speed variations in 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.
Gearing
The gearing for each axle is of the spiral bevel design with drive pinion positioned at centerline of the ring gear. The differential
and drive pinion are mounted on tapered roller bearings. The wheel differential is a 4 pinion and 2 side gear design.
Lube Pump
Tandem Axles with suffix letter "P" in Model No. are equipped with a lube pump to provide positive lubrication to the inter- axle
differential and other power divider parts. This pump is operated by a drive gear engaged with the input shaft splines. When vehicle
is moving in a forward direction, pressurized lube is delivered to the vital power divider parts. The pump lube system incorporates
a magnetic strainer screen. To keep the system clean, the magnet traps minute particles and the screen blocks out large particles
of foreign material.
Lube Pump System