STARTING AND DRIVING
AXLES
Interwheel Differential Lock Switch
CAUTION
DO NOT rely on gauges to determine axle
pressure. Weight must be veried on
scales. Adjust the air spring pressure
accordingly.
Regulators for adjusting the air spring
pressure are on the outside of the cab,
below the rear corner of the driver side
door. Regulators are operated by turning
the knob counterclockwise for lowering
pressure, and clockwise for increasing
pressure.
CAUTION
The maximum safe operating oil
temperature for a Mack rear axle is 121°C
(250°F) for mineral-based oil, and 148°C
(300°F) for synthetic-based oil. Continued
operation with oil above this temperature
will result in rapid deterioration of the oil's
lubricating properties and is NOT
recommended.
NOTE
Even when no traction is available at the
spinning wheel, the driver can "feather"
the brakes (apply the brakes slightly),
creating enough resistance at that wheel
to allow power to the axle with traction.
Feathering brakes should not be done
with power divider lockout engaged.
Engaging the Power Divider
Lockout
Inter-Axle Power Divider Lockout
The Mack power divider can be
rendered inoperative, during short
periods of poor traction, using a power
divider lockout. When the power divider
lockout is engaged, both axles are
locked together (in positive through-
drive) for maximum traction with no
differential action between axles.
It is not necessary to stop the vehicle to
engage the power divider lockout.
However, the lockout should be
engaged while the vehicle is stationary
or is moving at less than 40 Kph (25
mph).
CAUTION
To avoid component damage, do not
engage the power divider lockout if the
wheels are spinning.
Normally, the Power Divider switch is in
the OUT (disengaged) position. In poor
traction conditions, it may be necessary
to provide positive through-drive to both
axles by ipping the switch to the locked
(engaged) position.
1 Push switch to engage.
2 Momentarily release the accelerator
pedal to allow the shift to take place,
then drive through the slippery area.
3 When driving conditions permit,
unlock the power divider by moving
the Power Divider switch back to the
OUT (disengaged) position. Then
release the accelerator pedal
momentarily (to shift out of the
locked position) and drive as usual.
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X Publication_PC28
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