TEBS E
5
braking system
25
Multi-axle units
Axles or wheels which have no sensors fitted are controlled by directly controlled
axles or wheels. Multi-axle units require an almost identical adhesion utilisation on
these axles when braking.
If not all wheels have sensors, those axles that have the greatest tendency to lock
up need to be applied with ABS rotational speed sensors.
Multi-axle assemblies with static axle load allocation only should be equipped in
such a way (brake cylinders, length of brake levers, etc.) that the wheels of all ax-
les reach the locking limit as simultaneously as possible and a directly controlled
wheel does not indirectly control more than two wheels or one axle.
Lifting axles
2S/2M: Lifting axles must not be sensed.
All other system configurations with at least 4S with the exception of drawbar trail-
ers: Lifting axles can be fitted with ABS rotational speed sensors e-f.
2 axle vehicles with two lifting axles are supported as a 4S/2M system.
TEBS E automatically detects which axle is lifted and uses the axle on
the ground as the main axle, see chapter 6.24 ‘Forklift control’,
page 115.
Tag axles
Vehicles with tag axles must be equipped with a 4S/2M+1M or 4S/3M system to
prevent the tag axle from locking up.
If the frame is more rigid (e.g. box bodies), a 4S/3M system must be used to pre-
vent the outside wheel from locking up when braking in corners.
Steering axles
Constrained controlled axles are to be treated as rigid axles.
WABCO recommendation: Trailers with self-steering axles are configured with
4S/3M, 4S/2M+1M or 2S/2M+SLV. If the vehicle is equipped with RSS, one of
these configurations must be used to prevent the vehicle from breaking away in a
curve when RSS actuates.
2S/2M or 4S/2M EBS systems with steering axles: During the type approval for a
trailer, driving tests are to ensure that no impermissible vibrations or course devia-
tions occur. The reactions of all available steering axles must be evaluated during
an ABS test. If additional stability is required during ABS operation for a self-
steering axle, the steering axle should be switched to rigid using the speed switch
(ISS).
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