Spicer Single Drive Axles Service Manual: 34DS, 34RS, 38DS, 38RS, DS340, RS340, DS380, RS380, DS400, RS400, DS3 - Manual (Page 9)

General Information
6
Ser
vice Procedure
Torque Distribution with Lockout Disengaged (Inter-axle Differential is Operation)
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, inter-axle driveline, to the drive pinion, ring gear, wheel differential and axle shafts.
Torque Distribution with Lockout Engaged (inter-axle Differential is Not Operation)
A lockout mechanism is incorporated in the power divider to enable the vehicle driver to lock out the inter-axle differential and
provide maximum traction under adverse road conditions. In operation, an air cylinder (controlled by a cab-mounted valve) shifts
a sliding clutch. To lock out inter-axle differential action, the clutch engages the helical-side gear and causes this gear, the input
shaft and differential to rotate as one assembly. This action provides a positive drive to both axles. With Lockout engaged, torque
is distributed to both-axles without differential action. The forward axle pinion and ring gear are driven by the helical side gear.
The rear axle gearing is driven from the output shaft side gear and inter-axle driveline.
Note: Varied road surface conditions can result in unequal torque distribution between the two axle assemblies.
Input torque
Lockout disengaged Drive is from differential
through helical gears to
forward gearing
Drive is
from differential
through output
shaft to
rear gearing
Torque is transmitted to both axles through inter-axle differential action.
Inter-axle differential
operating
Input torque
Lockout engaged Drive is from input shaft
through helical gears to
forward gearing
Drive is from
output shaft side
gear to rear
gearing
Torque is transmitted to both axles without inter-axle differential action.
Inter-axle differential
not operating