The Break parameter

If we're this far at Cutbank, we should be safe from a broken coupler.

The broken coupler bug, as it has become known, has frustrated many a MSTS user. The most notable ocurrence of this bug is at Cutbank on Marias Pass. There are also a couple of places on NEC where it occurs. Note that we're not talking about a coupler being broken when you immediatelely throttle up to notch 8 in your leading Dash 9 at the head of 3 other Dash 9s with 5000 tons behind you; in real life, couplers break, as they are designed to, with that sort of driver behaviour.

You may want to have a think about the locos, carriages (passenger cars) and wagons (freight cars) for which you want to alter the Break parameter to avoid further broken couplers at the bad track spots. Then you can leave most rolling stock as is and only edit what you need so as to complete an activity across Marias via Cutbank.

Once you've identified the locos and rolling stock you want to change, it's a simple job to open the loco's ENGine file or rolling stock's WAGon file in WordPad to edit the coupler breaking force value.

You may see on message boards that another method to eradicate the broken coupler bug is to change the BoundingBox parameter; web•Wiz hasn't tried this method and it seems more complicated.

ENG file

Open WordPad and open the ENG file for editing. You'll see the Break value a few lines down on the opening screen:

SIMISA@@@@@@@@@@JINX0D0t______

Wagon ( SD40_BNSF1234
      Comment ( ** Snippet from ENG file** )
      Type ( Engine )
      WagonShape ( SD40_BNSF1234.s )
      Size ( 10ft 15ft+10in 65ft+1in )
      Mass ( 176.4t )
      WheelRadius ( 20in )
      InertiaTensor ( Box (10ft 15ft+10in 65ft) )
      Coupling (
        Type ( Automatic )
        Spring (
          Stiffness ( 1e6N/m 5e6N/m )
            Damping ( 1.2e6N/m 1.2e6N/m )
              Break ( 1.6e7N 1.6e7N )
                r0 ( 20cm 30cm )
                )
          Velocity ( 0.1m/s )
      )

Edit both values so the line reads:

Break ( 5.1e7N 5.1e7N )

Save this file and repeat the process for any other locos that you've decided to change.

Sometimes you'll see that the loco's designer has made the change already.

By the way, realistic values for Break are usually set as:

Break ( 1.6e7N 1.6e7N )

or, for a loco such as an SD90MAC:

Break ( 2.4e7N 2.4e7N )

WAG file

The task for a carriage or freight wagon is similar to that above. Start WordPad and open the WAG file for the particular carriage or freight wagon. You'll see the Break value line just a few lines down from the top of the file:

SIMISA@@@@@@@@@@JINX0D0t______

Wagon ( bnsf_fl  
      Comment( ** BNSF Coal Car Full Load ** )
      Type ( Freight )
      WagonShape ( bnsf_fl.s )
      Size ( 3.1m 3.77019m 14.70m)
      Comment( 26.7t empty, 117.41t full )
      Mass ( 117.41t )
      WheelRadius ( 36in/2 )
      InertiaTensor ( Box (3.1m 2.7m 14.70m) )
      Coupling (
         Type ( Automatic )
         Spring (
           Stiffness ( 1e6N/m 5e6N/m )
             Damping ( 1e6N/m 1e6N/m )
               Break ( 1.1e7N 1.1e7N )
               r0 ( 20cm 30cm )
       )

Edit both values so the line reads:

Break ( 5.1e7N 5.1e7N )

Save this file and repeat the process for any other wagons that you've decided to change.