Check braking characteristics of trailer

1 Apply pressure graduations (pm) to the coupling head for brake according to the test sheet and enter the brake cylinder pressures (p1, p2) and brake forces (F1 to F3) achieved for each wheel in the test sheet. Note the locking limit.

 Use the form "Test sheet on the braking characteristics of tractor vehicles and trailers" Only use values below the locking limit. Perform the pressure graduation in an ascending manner and check at the highest possible pressure, releasing the service brake again continuously.

If the trailer is checked with a tractor vehicle with electropneumatic brake (EPB/BS/EBS), the least applicable pressure amounts to 0.7 bar at coupling head for brake (depending on the Inshot function).

-----------------------------------------------------------------------------------------

2 Add the brake forces (F1 to F3) of the individual axles together and enter the sum of brake forces (FA) of the trailer, referenced to the individual pressure graduations (pm), in the test sheet.

3 Calculate braking ratio (z) for each pressure graduation (pm).

Total of brake forces (FA)

z =  100 (%)

Sum of permissible axle loads (GA)

-----------------------------------------------------------------------------------------

Example of brake application (z) of trailer:

Sum of brake forces (FA) with pm 2.0 bar = 3150 daN

Sum of permissible axle loads (GA) = 22,800 kg

3150

z =  100 (%) = 13.8 %

22.800

 At a pressure of 1 bar at the coupling head for brake, braking effect must already be showing at the wheel.

Example of brake forces calculated:

Coupling head for brake Total

pm (bar) FA (daN) z (%)

0,0 410 1.8

0,5 640 2,8

1,0 990 4,3

1,5 2150 9,4

2,0 3150 13,8

2,5 3860 16,9

3,0 4900 21,5

4,0 6700 29,4

5,0 7900 34,6

6,5 BG* BG*

>8.5  

* Locking limit

W42.00-1028-81

4 Transfer the calculated braking values (z) for each pressure graduation (pm) from the test sheet to the EC braking rate band. Connecting the points will result in a curve, which is the braking curve (braking characteristics) of the trailer or the semitrailer.

 If the braking curve is outside the EC braking rate band or if too high response pressures are found, a complaint must be raised about the brake. The brake system of the trailer or semitrailer must then be checked and any faults or signs of wear found must be eliminated.
Changes to the brake system are only permissible in consultation with the automotive manufacturer.

2 Braking curve of the semitrailer

V EC braking rate band of loaded semitrailer