Quacking Duck Posted February 4 Posted February 4 (edited) There are two brake-related buttons on the control panel of the Dragon 2 locomotive whose functions I do not understand. When the "brake releaser" button is pressed, it rapidly reduces the indicated brake cylinder pressure to 0, but only while it is pressed. When the button is released, brake cylinder pressure returns to approximately its original level. I had originally assumed that this button could accelerate the process of releasing the train's brakes. However, using this button while the brakes are releasing, after having charged the brake pipe to above 5 bar, does not appear to accelerate brake release in any useful way. It appears that there is a "true" level of brake cylinder pressure which can only decrease slowly. When the button is released, indicated brake cylinder pressure returns to that level. Under what circumstances, if any, does this button actually help to release the brakes? Toward the right side of the control panel, near the brake gauges, there is a "brake assimilation" button. Pressing it has no obvious effect. What does this button do, and under what circumstances is it used? Edited February 4 by Quacking Duck 1
jeroezie Posted February 4 Posted February 4 The brake releaser do only work on the locomotives brakes. With old stock, like EU08, EP08 etc. this drains air from a very slow filling reservoir, so the effect will last long. On more modern stock such as Br 186 and dragon locomotives, it drains the locomotives brakes only when being actually pressed. The brake assimilation increased the brake line pressure from 5,0 bar to 5,4 bar. This is to deal with pressure differences in the brake pipe. It will also ensure all triple valves (this valve translates the brake pipe pressure to cylinder pressure that goes to the actual brakes) have an adequate pipe pressure, so they release the brake full, even if they are overcharged (for example by a previous pressure spike). The brake assimilation or fill position, depending on the locomotive, does use a higher pressure and/or a bigger 'hole' in the brake leaver, to fill the brake pipe, so it is a much faster process and filling it only using drive/release position. But you have to be careful to NOT overcharge the triple valves.
Quacking Duck Posted February 14 Author Posted February 14 Thank you for explaining what those buttons do. In what situation, and for what purpose, is the brake releaser intended to be used?
Agent B-7 Posted Friday at 08:49 PM Posted Friday at 08:49 PM On 2/14/2026 at 10:52 AM, Quacking Duck said: Thank you for explaining what those buttons do. In what situation, and for what purpose, is the brake releaser intended to be used? I use it to unlock the pneumatic traction lock on the locomotives that have it. Allows to apply the power while the rear of the train is still releasing the brakes, helps with hillstart etc (the brakes in the back will be eventually released and you already have some traction). Another thing is if you're switching and the brakes are in the T/G mode. If you intend to use only the local brake, you can keep it there and release the first time quickly with it. I know Americans use the independent brake bail to modulate the brake force or to use only dynamic brake on the loco itself, but it's definitely not intended use in Europe.
jeroezie Posted Friday at 09:03 PM Posted Friday at 09:03 PM 12 minutes ago, Agent B-7 said: I use it to unlock the pneumatic traction lock on the locomotives that have it. Allows to apply the power while the rear of the train is still releasing the brakes, helps with hillstart etc (the brakes in the back will be eventually released and you already have some traction). Another thing is if you're switching and the brakes are in the T/G mode. If you intend to use only the local brake, you can keep it there and release the first time quickly with it. I know Americans use the independent brake bail to modulate the brake force or to use only dynamic brake on the loco itself, but it's definitely not intended use in Europe. One should not have the loco in G when shunting.... This is one of the first things they will ask if you have a accident/spad when you are shunting (or driving an P brake train).
Quacking Duck Posted 13 hours ago Author Posted 13 hours ago What are "T" and "G"? Does the "brake assimilation" button do exactly the same thing as the "fill" position on the brake lever? If no, what is the difference, and what is the significance of the difference?
Agent B-7 Posted 3 hours ago Posted 3 hours ago 10 hours ago, Quacking Duck said: What are "T" and "G"? There are three main brake timing options (in Germany, Poland, Austria etc, but could be different otherwise): T or G (Towarowy/Güter, freight), P (in the past, passenger, now mostly fast freight), and R (rapid, fast passenger, but now basically any passenger). This determines how fast the brakes are released after pressurizing the main line on the locomotive and affected cars. The point is to delay the release on the front of the consist to make the release moment closer to the end of the consist, to make the brake release more uniform. 10 hours ago, Quacking Duck said: Does the "brake assimilation" button do exactly the same thing as the "fill" position on the brake lever? If no, what is the difference, and what is the significance of the difference? No, not sure if the Polish valves are any different, but in German context, the Fast Release (Fill) position is venting the main res to the brake line but doesn't intentionally overcharge over 5 bars, the relief valve is still active and will prevent excessive pressure. The point is to get the line to 5 bars ASAP. Brake overcharge/assimilation gets the pipe pressure above 5 bars (in Germany the typical limit is around 5.5), and the point is to not just release the brakes on the whole consist, but also fully charge auxiliary reservoirs on all the cars (that feed the brake cylinders on cars, they charge only when the brakes are fully released).
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