Spicer Tandem Drive Axles Service Manual D__R440, 460, 480, D_R461, 462, 463, 521, 581, 601, 651, 652, 653 - Manual (Page 133)

129
Theory of Operation
Theor
y of Operation
Theory of Operation
Spicer tandem drive axles described in this publication are sin-
gle reduction units designed primarily for heavy-duty hauling
on and on/off highway.
This type axle assembly provides a vehicle with superior load
carrying and roadability characteristics by dividing its work be-
tween two axles. The complete tandem assembly consists of
two axle units coupled by a power divider.
Power Divider
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 a 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-operat-
ed 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 four-pinion, two side gear design.
Lube Pump
These tandem axles are equipped with a lube pump to provide
a positive lubrication to the inter-axle differential and other
power divider parts. This pump is operated by a drive gear en-
gaged 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.
Reference
Spicer Lubrication Brochure TCMT-0019 for more
information on lube.
Differential Lock-up Assembly
The
Spicer wheel differential lock is driver controlled and oper-
ated by a carrier-mounted, air-actuated shift unit. In operation
it positively locks the wheel differential to provide improved
traction under adverse road conditions.