Volvo VNL Operator's Manual page 284

Parking Brake Release
VN models have engines equipped with en-
gine electronic control units (EECU). These
have two features that may impact the
brake system. One is the anti-stall device in
the EECU which senses torque demand and
automatically controls the engine to com-
pensate and maintain speed. On tractors
equipped with parking brakes on only one
axle, the anti-stall device keeps the engine
from stalling, allowing the driver to pull
away with the brakes dragging. This may
result in overheated brakes and damaged
wheel hubs.
WARNING
Continual dragging of the brakes will
cause brakes to overheat. This may lead
to wheel end fire. To avoid overheating,
make sure both parking brake knobs are
pushed in before driving off.
If the yellow knob is pulled out and the red
knob is pushed in, a condition is created
where the trailer parking brakes are not ap-
plied and only the single drive axle brakes
are applied. In this condition, the vehicle
can be driven away. Therefore, it is very
important that the driver make sure the yel-
low AND red knobs are pushed in all the
way before driving the vehicle.
Brakes
W5001116
Correct Driving Position:
Both knobs fully in
279
W5001114