ar4225w002002naa

Check braking behavior on trailer vehicle

Type ar · emne 42.25 · version 0100 · 2014-04-17

Gælder for: MODEL 967 with CODE B1Y (ABS brakes)

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Placering

Funktionsgruppe 2 Chassis › 42 Bremsehydraulik og -mekanik › 42.25 Elektro-pneumatisk bremse (EPB) — Serie 967

EinPAS 21 bremser/vakuumsystem/trykluftsystem › 21.17 Anhængerbremse › 21.17.1 Grundinformation — Serie 967

AR42.25-W-0020-02NAA

Check braking behavior on trailer vehicle

Test sheet on the braking characteristics of tractor vehicles and trailers, form

OF42.10-W-3000-01NAA

MODEL

967

with CODE B1Y (ABS brakes)

1

Apply pressure graduations (pm) to the brake coupling head according to the test sheet and enter the brake cylinder pressures (p1 to p3) 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 test of the trailer is conducted using a tractor with an electronic brake system (EPB/BS/EBS), the smallest (dependent on inshot function) applicable pressure is 0.7 bar on the coupling head for the brake.

2

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

3

Calculate braking ratio (z) for each pressure graduation (pm).
Example of determining the braking ratio (z) of the trailer vehicle:
Total brake forces (FA) at pm 2.0 bar = 3150 daN
Total permissible axle loads (GA) = 22,800 kg
3150 daN 22,800 kg x 100 % = 13.8 %

Example of determined brake forces:

Total coupling head for brakes

   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           BG1)         BG1)

>8.5

1) Blocking limit

At a pressure of 1_bar at the coupling head for brake, the braking effect must already be evident at the wheel.

Check braking behavior on trailer vehicle

4

Transfer the calculated braking values (z) for each pressure graduation (pm) from the test sheet to the EC trailer braking band. A curve is created by connecting the points, which displays the braking rate band (brake characteristics) of trailer or semi-trailer.


If the braking curve is outside the EC braking band or if too high response pressures are recorded, there is something wrong with the brakes. The brake system of the trailer or the semi-trailer must then be checked and faults or signs of wear found must be eliminated. Changes to the brake system are only permissible in consultation with the automotive manufacturer.


2

Semitrailer's braking-ratio characteristic

V

EC braking rate band, load semitrailer

W42.00-1028-81

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