Need to learn about dynamic braking

[cnbalasub]

I need a lot of practice with dynamic braking and what is the best result for me to learn and understand how to run the train downhill like Canadian Mountain Pass and some other U.S. routes that I can't remember right now. I have no idea how to control the train down hill with dynamic braking like the cab controls. I did look up some of the videos on YouTube but need to learn and get more familiar with Train Simulator 2021.

Let me know what or where to find the information or learning step by step in the leading cab with the train going downhill.

Thank you,

John

[EngineerJohn]

Dynamic brakes turn the electric motors in the wheels into generators. The wheels spinning the coils in the electric motors. Normally this resistance is overcome by using a giant diesel motor but now the flow of energy is reversed, and to get rid of all of this built up electricity with no place to go, the locomotive has giant resistor blocks to turn the energy into heat and get rid of it (hence the dynamic brake fans).

Dynamic brake physics vary wildly depending on the locomotive and physics pack so just be aware of that. Some dynamic brakes when they kick in really shove the engine hard against the train almost instantly and are almost magical in their stopping power...

Firstly dynamic brakes need to be used along with some amount of train brake. The dynamic brakes only work on the locomotives in the consist so the cars will bunch up against the locomotives effectively pushing them unless some amount of train brake is applied to keep them under control.

The other big thing is dynamic brakes take a while to come online, usually 10-15 seconds, so you'll need to anticipate when you'll need them (like when a significant portion of the train passes the crest of a hill and starts to descend rather than waiting for the full thing to get over the top).

Also at low speeds ( about 15mph or less) dynamic brakes no longer work as the wheels aren't turning fast enough to generate a significant enough amount of energy to act as resistance, so the brakes fade and require almost exclusive use of the air brakes.

[cnwfan]

It is my understanding that with the newer locomotives with AC traction motors, dynamic brakes will work down to a few miles per hour, unlike the older locos with DC motors which do fade out at low speeds. During the EMD Dash 2 days, the manufacturer offered extended range dynamic brakes which would be effective in lower speeds.

From an operational sim aspect, I try to balance my power so that when half my train length has passed a summit crest, my dynamics are in setup, and my speed is no more than 5 mph less than the posted speed limit or speed limit as specified by train weight. So if the speed limit is 20, I'm doing no more than 15. I adjust the dynamic braking strength to maintain speed. If I get to 50% dynamic brakes and train speed is still increasing, I'll make a minimum train brake set, and will adjust the dynamics as the train brakes take effect. Once the dynamic and train brakes are in balance, you should be able to small adjustments to the dynamic brakes in order to maintain a constant speed.

In the sim it isn't as relevant, but you want to avoid cycling (setting and releasing) your train brakes. It's better to use a small starting set, and increase train brakes incrementally than do a large set, and having to release due to the train bogging down. It takes time for train brakes to fully recharge, and if you make a set, release, and try to set again... the brake set will be less effective or worse... will not be effective at all.

The baseline TS train physics are not that great, but the Searchlight Simulations folks have done the best job at replicating real world physics given how the sim is structured. So if you're running their SD40-2's, AC4400, or really any of their sound enhancement packs, locomotive and train handling will be more "prototypical".

Bringing a train, let alone a heavy train, down a grade safely is part skill, part art, and part experience. Good luck, and enjoy the challenge!