Choosing a ProtoThrottle Braking Mode

There are two main braking modes in the ProtoThrottle. The default mode is a basic on/off (VAR BRK = OFF) brake. When you move the brake handle right, past the brake threshold (approximately mid-way), the assigned brake function is activated in the locomotive decoder. When you cross that threshold moving the brake handle left, the assigned function is deactivated. Simple and straightforward. This is equivalent to what you get with a standard function button on a traditional throttle.

The second mode is called variable braking (VAR BRK = ON). This mode actually has 2 sub-classes, depending on decoder type. The first version is pulse braking (BRK TYPE = PULSE). In this mode, the position of the throttle handle determines the amount of braking effect. From 0-19%, the brake function is off. From 20%-39%, the brake function is pulsed so that it is active 25% of the time. 40%-59% = active 50% of the time. 60%-79% = active 75%. Greater than 80% = active continuously.

Pulse braking works well with Tsunami2 decoders (usually with the brake release sound turned off, though, as you would otherwise get the brake release “whoosh” pulsing on and off). It also works well with Loksound decoders, but NOT with the Full Throttle independent brake – the pulsing interacts with the sound schedule behind the Full Throttle independent brake and produces inconsistent results. Instead, for Loksound decoders, assign the brake function to the “dynamic brake” logical function in the decoder, with no sound slot assigned to it. See appendix below for details.

The second sub-class of variable braking is step braking (BRK TYPE = STEP). This is intended for TCS WOWSound decoders and takes advantage of their unique 5 step graduated braking feature.

step-brake

As the throttle handle is moved right, the brake function is momentarily activated to advance the decoder to the next higher level of braking. This continues across the full range of the brake handle until the 5th (and strongest) level is active. Once the brake handle is moved back fully left, the brake OFF function is activated, releasing the brakes. Note that you cannot reduce the braking level – only increase or fully release. This is a limitation of the decoder, not the ProtoThrottle.

One final point – when using the variable brake (of either variety), our recommendation is to turn off the emergency brake. Trying to distinguish between >80% for full braking and the emergency brake at full right can be tough at times, especially in the heat of battle.


Appendix – Loksound Variable Brake

Loksound decoders require a little tweaking to get them to work well with the ProtoThrottle variable brake feature.  First, don’t use the Full Throttle independent brake – it does not interact well with the pulsing of the variable brake.  Instead, assign the brake function to the “dynamic brake” logical function in the decoder, with no sound slot assigned to it.  This works really well and gives you a variable brake effect.  However, one more caveat – it doesn’t hold the locomotive stopped if the brake is set. To solve this, you can create two function mappings for the brake, one with Driving = No and the other with Driving = Yes. Assign Drive Hold to the Driving = No (Stop) setting. See example below.

brakes

I arbitrarily assigned F28 as the brake function, but you can use any available function. Note: F27 is set up the same, but I also have it light the number boards when the brake is active. Obviously this is not an operating mode, but is VERY handy when first playing with the brake and debugging what’s going on in the decoder – instant feedback that you are at least pulsing the brake and at what rate.

Comments

  1. I have a NCE power cab that I’m using with PT, I’ve figured everything out with the dynamic pulse braking expect being able to get rid of the sound. Most of my fleet is scale trains, Loksound 4, and 5. I can’t find anywhere as to what cv to change?

    1. Do you have a LokProgrammer or are you trying to do the configuration entirely with normal CV changing? Are you changing them using JMRI or are you doing it all manually? The answer is going to be a bit dependent on how the Loksounds are configured and exactly what you want it to do. Suffice to say it’s going to be more in-depth than a blog post response can probably handle. Could you ask that on the ProtoThrottle list ( https://groups.io/g/ProtoThrottle/ ) or email us directly at support@iascaled.com – we’d be happy to help.

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