Spicer Tandem Drive Axle Dual Range & Double Planetary 34,000-45,000 lbs - Manual (Page 60)

Dual Range Axle Shift Systems
Standard System for Axle Range Selection
and Inter-Ax/e Differential Lockout
(straight-air type)
Air pressure with axle in High Range,
Inter-Axle Differential Engaged.
Pressure switch and speedometer adapter Solenold valve required for vehicles
required for vehicles with transmission not equipped with automatic safety brakes.
drive speedometers.
Description
The standard dual range shift system
consists of:
1.
A manually-operated, air shifter
valve to change axle range.
2.
A quick release valve which
provides for fast release of air pres-
sure from the axle shift units.
3.
Two air shift units mounted on the
axles. These shift units are mechani-
cally connected to the axle shift forks
and sliding clutches which, in turn,
shift axles into Low or High Range.
For vehicles not equipped with auto-
matic safety brakes,
an ignition-
controlled solenoid valve exhausts
the system and downshifts the axles
when the ignition switch is turned off.
The electrical circuit is protected by a
circuit breaker.
For vehicles equipped with transmis-
sion-drive speedometers, the system
includes a speedometer adapter which
compensates speedometer readings
when axle is in Low Range. The
adapter is operated by an electrical
switch mounted on or near the quick-
release valve. The switch is normally-
closed and is opened by air pressure.
With axles in Low Range, the switch
is closed and the adapter is energized.
The adapter operates with a ratio
compatible with the axle Low Range
for proper speed readings. With axle
in High Range, the air lines are pres-
surized and the pressure switch is
open. The adapter now operates
with 1:1 ratio for proper speed
readings in High Range.
Axle Shift System Operation
High Range.
When shifter valve is
moved to the High position, the valve
is opened and air pressure is supplied
through the quick release valve to
both axle shift units. When driveline
torque is interrupted, the shift units
will shift both axles to High Range.
Low Range.
When shifter valve is
moved to the Low position, the valve
is closed. Air pressure in the shift
units is exhausted through the quick
release valve. When driveline torque
is interrupted, both axles are shifted
to Low Range and held in this position
by shift unit return springs.
Inter-Axle Diff. Lockout System
The lockout air shift system
consists of:
1.
A manually-operated air shifter
valve which controls engagement
or disengagement of the inter-axle
differential.
2.
A lockout cylinder which oper-
ates under air pressure. This cylin-
der is mechanically-connected to a
shift fork and sliding clutch. The
clutch engages or disengages a
differential helical-side gear to
“Lock” or “Unlock” the differential.
Lockout System Operation.
For
operation description, refer to the
following page.
61
.