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Thread: Dynamic Brake

  1. #1
    roger01 Guest

    Default Dynamic Brake

    I'm new to this, recently installed MSTS, and can't seem to find the answer to what effect I should see from using the Dynamic Braking capabilities of the diesel trains. When I apply it I never see any braking action occur. Can someone please explain it, how to use it, and what action occurs? Thanks...Roger

  2. #2
    Join Date
    Nov 1999

    Default RE: Dynamic Brake

    Dynamic braking is where the traction motors are "turned" into generators. This slows the loco down. Kind of like a "jake-brake" on a semi. Most loco designers for MSTS use actual physics of Dynmaic braking. The Dash9 Dynamic brakes usually work at 60mph or less and will not engage over 60mph. My F7 loco's DB's won't engage until I am under 45mph. Every loco can be different. They are mainly used to control speed and slow the train down without using air brakes and therefore cutting down brake shoe wear.

  3. #3

    Default RE: Dynamic Brake

    There is about a prototypical 10 second time lag before dynamics can be used when transitioning from throttle (DB Setup). There is the same lag before throttle can be used when coming out of dynamics.

    Most eng files allow for a 4-5 second lag going into dynamics, and zero coming back out. While the "coming back out" is apparently not hardcoded by MSTS, you can easily adjust the lag going into dynamics in the eng file, if you are into tweaking it. In Wordpad or better, find the line which says:

    "DynamicBrakesDelayTimeBeforeEngaging ( 10 )" (or whatever value you find) and change the ( 10 ) to ( 20 ). Apparently the units used by MS are half-seconds, as 10 will give you 5 seconds; 20 will give you 10.

  4. #4
    Join Date
    Sep 2003

    Default RE: Dynamic Brake

    Peter Baker in his original document "Dynamic Brake Physics Upgrade v1.0" which is available in the files downloads section points out a bug in MSTS, namely that just when you need dynamic braking at maximum speed, you haven't got any. He writes:

    "According to the MSTS Tech Docs the amount dynamic braking effort available at point 4 is supposed to be defined by the variable DynamicBrakesEffectAtMaximumFadeOut. However, I have found out by testing that it doesnít make any difference what value is put here, as the braking effect is always 0 at that maximum speed. This is caused by a bug in the program. At speeds higher than that speed the braking force instantly jumps to the proportion of dynamic braking force specified by this variable.

    "I have decided that it is best to set this amount to be 0 (Zero) in all cases and then to change some other variables to lengthen the overall curve. I did this by increasing the speed specified in DynamicBrakesMaximumSpeedForFadeOut and then increasing the curve exponent set in DynamicBrakesHigherSpeedCurveExponent in order to achieve the a similar result."

    You could try doing that and see if it helps. His latest version of locomotive physics, 4.11 (, should have this fix included in his engine files.

  5. #5
    roger01 Guest

    Default RE: Dynamic Brake

    Thank you all for the excellent information. Roger

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