6
TEBS E
GIO functions
78
6.7 Traction help
Vehicle type
All air suspended trailer vehicles with lifting axle or tag axle as first axle.
Purpose
On slippery ground or on steep hills vehicles have a hard time pulling away or can-
not do so at all. The drive axle of the towing vehicle does not have enough traction
and the wheels spin.
Function
With traction help, the 1st axle on a semitrailer can be raised or relieved of pres-
sure. The subsequent weight adjustment on the semitrailer coupling causes the
traction of the drive axle on the towing vehicle to increase.
The effect of the traction help function depends on the load status. The support
bellow pressure monitors the load on the trailer's main axle.
Once 30 % overload is reached, the tag axle is not relieved any further. Traction
help is started by the driver or is started automatically.
When reaching 30 km/h, the axle is lowered again or returns to automatic mode.
Note the axle manufacturer's information on traction help. These specifications may
restrict the maximum limits of the EC Directive 98/12/EEC.
Valve configurations
The following variants can be selected:
• A spring-returned lifting axle valve (not suitable for all vehicles)
The lifting axle can be lifted as a traction help, providing the permitted bellows
pressure set in the parameters is not exceeded after lifting. If the permitted
pressure is exceeded when traction help is active, traction help is cancelled and
the respective lifting axle is lowered.
In countries where axle loads of 3 times 9 t are permitted, traction help is can-
celled as soon as the load on the axles that remain in the ground exceeds
23.4 t. The effect of traction help is thus linked to the load status.
• One lifting axle valve (spring returned) and one solenoid valve for pres-
sure limitation (residual pressure maintenance)
The load is transferred off the lifting axle as a traction help, up to the level of the
permitted bellows pressure set in the parameters. Then the support bellow of
the lifting axle are shut off using the solenoid valve. The lifting axle is thereby
relieved for best possible traction when starting without exceeding the 30%
overload (the value defined in the parameters) on the other axles.
(The lifting axle remains relieved at 130% axle load on the main axle and is
lowered again only at 30km/h.)
This configuration permits traction help even when the vehicle is overloaded.
• A pulse-controlled lifting axle valve
The load is transferred off the lifting axle as a traction help, up to the level of the
permitted bellows pressure set in the parameters. Then the support and lifting
bellow on the lifting axle are shut off. Therefore, relieving the lifting axle may
also be performed in order to prevent the permissible 30% overload being ex-
ceeded.
(The lifting axle remains relieved at 130% axle load on the main axle and is
lowered again only at 30km/h.)
This arrangement makes sense in countries with a permissible axle load of 9 t.
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