How Do I Choose 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 squeal turned off, though, as it can sound strange with the squeal 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, just 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 attached example. 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.

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. See page 15 of the ProtoThrottle manual for a diagram of this mode. 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 other 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.

Leave a Reply

Your email address will not be published. Required fields are marked *