11
TEBS E
Workshop notes
190
11.6 Tuning the vehicle
If there are wear or adjustment problems between the towing and trailer vehicles,
the TEBS E Diagnostic Software can be used for setting a predominance or a de-
lay with the ‘Predominance’ parameter see chapter 9.1 ‘Parameter definition with
TEBS E Diagnostic Software’, page 165 => Wind
ow TEBS - LSV.
Change the braking pressures only if the wheel brakes are good and the pads have
recently been replaced.
Test the response pressures
In order to exclude faulty wheel brake functionality, the actuation pressures have to
be checked first:
– First, measure the braking forces of all axles on a roller test stand and deter-
mine the position of the individual vehicles.
For trailers the following values should be reached ‘unladen’ and ‘laden’:
p
m
= 0.7 bar = Brake begin
2,0 bar = Deceleration approximately 12 %
6,5 bar = Deceleration approximately 55 %
If the start of braking is above 0.8 bar, the threshold pressures on all the
wheel brakes must be measured.
Check the response pressures of all wheel brakes
– Provide the vehicle with compressed air and power.
– Connect the TEBS E Diagnostic Software.
– Click on Control, pressure test.
– Block up the vehicle (1st axle).
– Simulate the bellows pressure for the laden vehicle.
– Turn one wheel and increase the control pressure in 0.1 bar steps (left and right
cursor keys).
– Determine the braking pressure (cylinder pressure not control pressure!) at
which the wheel becomes difficult or impossible to turn.
– Repeat the test on the other wheels.
– Calculate the average value of the determined response pressures and com-
pare this value with the parameterised value.
You may need to set the newly determined value in the parameters.
Example
Defined response pressure = 0.3 bar
measured:
1st axle right = 0.6 bar; 2nd axle right = 0.5 bar; 3rd axle right = 0.5 bar
1st axle left = 0.5 bar; 2nd axle left = 0.5 bar; 3rd axle left = 0.6 bar
Average threshold = 0.53 bar => rounded to 0.5 bar
The difference between the two values of 0.2 bar must be added to the braking
pressures.
In this example the laden braking pressures would be adjusted thus:
• 0.3 bar goes to 0.5 bar
• 1.2 bar goes to 1.4 bar
• 6.2 bar goes to 6.4 bar
• also the unladen braking pressure of 1.3 goes to 1.5 bar
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