Volvo FM Handbook page 172

can be used to increase traction when stuck on a
slippery surface.
1 Press the lower part of the bogie switch once.
The load is distributed so that the drive axle carries a
heavier load than previously, but not more than the
axle load limitation. The bogie lamp is lit.
The function "Optimize traction" is activated. The
function distributes the load between the axles to
provide the best road grip possible with regard to the
load
2 Press the lower part of the bogie switch once more.
If the speed is less than 30 km/h when it is pressed:
The drive axle pressure increases to max 30% above
the axle pressure limit. The bogie lamp flashes.
When the speed increases to more than 30 km/h, the
drive axle load drops to the axle load limit again.
Driving 161
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