Spicer Tandem Drive Axle Dual Range & Double Planetary 34,000-45,000 lbs - Manual (Page 6)

Gearing and Torque Distribution
Dual Range Gearing
The gearing for each axle is a
combination of a spiral bevel ring
gear and pinion and a planetary
unit.
First reduction (High Range) is
provided by the spiral bevel
gearing.
Second reduction (Low Range) is
through the planetary gearing.
Four planetary idler pinions are
confined within the ring gear and
mesh with the ring gear internal
teeth. The planetary gears rotate
around a sliding clutch gear.
Each axle is equipped with a shift
unit, which operates the sliding
clutch gear to provide means for
selecting the axle range. Range
selection is accomplished through
the movement of the sliding clutch
gear in and out of engagement
with low and high-speed clutch
plates.
The sliding clutch gear is locked
into the high-speed clutch plate
and rotates as part of the differen-
tial assembly. The planetary pin-
ions are stationary and the axle
uses only the single reduction of
the ring gear and pinion. Power
flow is through the drive pinion,
ring gear, differential unit and axle
shafts.
The sliding clutch gear is shifted
into engagement with the low-
speed clutch plate (an integral
part of the bearing adjuster). The
sliding clutch is held stationary and
the planetary pinions are forced to
rotate around it. Power flow is now
through drive pinion, ring gear,
planetary gearing, differential unit
and axle shafts. The axle uses two
reductions to multiply torque. The
planetary unit adds approximately
36¡/0 more reduction to the primary
gear set. Torque is multiplied on
an equivalent basis.
Torque Distribution in High Range
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 sides.
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.
INPUT
TORQUE
Torque is transmitted to both axles through inter-axle
differential action.
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