Can someone check if this is true? I saw in a video that after the runaway train accidents in the 80's and 90's, the regs changed to make the Dynamic Brake remain engaged when minimum train braking is engaged. I have big issues with the 3% grade in the sim. If the Dynamic didn't disco I could use both types of braking.
There are certain points on that grade where you probably shouldn’t be going more than 15-20 mph tbh. Anything much faster and it becomes pretty hard to stay in control of the train. It can take a few runs to get the hang of it.
Yeah, it's not as easy driving the freight as I thought. I got it on 3rd try. Used E-brake a couple times but I completed the darn thing. Caused lots of red signals I guess. I agree, 10-20MPH max. It's a tough job to keep it there.
Very much this. It's mentioned in the tutorial but almost like it's something that might happen. Took me a while to get it right, but you can absolutely be going faster than 20 mph (if you want). Start with the dynamic brake, then add automatic either minimum or a bit stronger if you like, don't need much. The dynamic brake does cut out, so as stated, put the independent brake to bail off (all the way off) and the dynamic brake kicks in again and you will get good controlled braking. This is with the ES44C4. The SD40-2 dynamic brake doesn't cut out when you add the automatic brake.
The correct technique is probably to hold the independent brake handle in Bail-Off while making any train brake application with the dynamic brakes active. American locomotives would probably benefit from a version of the European practice, where the locomotive's friction brake application resulting from the train brake pipe is automatically held off if the dynamic brakes are in operation - rather than the reverse as seems to be applied at present. Only when the train speed falls below the effective speed for dynamic brakes is the friction brake progressively brought in.
In real life, when in dynamic brake, the locomotive automatically bails off the independant. Well in Australia too but I believe this happens in the USA. So it is possible that an update in future can resolve this.
I don't agree. The driver of a big US freight- who IRL is controlling multiple MUs remotely - needs to have complete and independent control of the braking systems, and employ them as necessary. Not being able to add air to the dynamics, in particular, sounds like a recipe for runaways. Also, I'm fairly certain that that interlock in European trains is not their to avoid the bail-off issue, but to prevent the blended-braking system from overusing the train brake and bleeding the system of air.
This is interesting. I will try the SD40 when the journey takes me there later, but the ES44 bail off trick doesn't seem to work for me. I can only make it down the hill with Emergency braking once the speed gets too high. Would like to do it more eloquently but hey, I did it.
The thing that used to catch me out was once you put the air brakes on, don't release them. If you keep applying & releasing you can't run out of air as the the rear of the train hasn't recharged even though all the dials will be indicating that they have. If you are needing the emergency brake at all then it sounds like this might be what is happening. If you apply too much air brake applied, come to a stop and then release and don't reapply them for a good 5 mins or more.
On the 4400 with +5000 tons on a >2.0% grade down. At 27mph or more the dynamics will not hold the train to speed at Max. 1)Keep dynamics at 100% 2) Apply Auto Brakes to Minimum 3) Quickly Bail off Independent Brakes. Hold Bail off for a second or two. You'll see dynamics come back to power. At higher speeds, such as 30-35+ your dynamics don't produce as much reverse force, so you'll need to do the same steps, but go for 25-50% on Auto Brakes on step 2. Eventually, as you slow, your dynamics will get crazy powerful. At around 26mph, you need to let the auto brakes release. Being new...Cajon drove me NUTS. PS For extra fun, press the EOTD switch (only if you've saved first. For the love of God only if you've saved)
To clarify, this is just holding off the friction brakes of the locomotive, not throughout the train. If the driver really wants the locomotive friction brakes combined with dynamics, he could always apply the independent brake, which would not be subject to this feature. And if the dynamic brake fails, the locomotive brakes would automatically apply as a substitute. Consider pages 44-45 from the BR Class 90 handbook.
While doing the G-HOULAC6-07 (ES44C4 with 14500 tons of freight on the 3% grade descent), it was more Don't go over 20 mph Full automatic brakes Bail-off the locomotive brakes Full dynamic brakes Pray you don't gain any more speed, and don't go over 30, or you'll need to use emergency brakes or the « Handle off » position (whatever this is, it's working nicer than the emergency) Using that method I was able to keep the train at bay, but I crossed my finger the whole way for not seeing a red, which would have been a challenge! This route is very hard, IHMO. I don't want to know what it's like when it's raining. EDIT: If you are reading this, read a bit further where we explain why my auto-brakes weren't enough to stop my trains (spoiler alert, it was my fault)
So, I've been doing a bunch of these recently. After initial frustration not seeming to have any control over the train at all I am now having fun with this route. (Note I am not a rl train driver, but this definitely works in the sim.) I have used both locomotives, the main driving difference between them as far as the sim goes is that the independent brake bail off is only necessary in the ES44C4 which I mentioned above. While even the in sim tutorial says the dynamic brake isn't effective above 30 mph, I have found it to be usable (at least on some routes) when in the mid 40's, and I've never needed to use full dynamic braking, usually between levels 2 and 5 and that has allowed me to control the speed just fine. That said, there comes a point when you will need the train brake also. Here is what I do in the ES44C4 and it works great. HTH. 1. Initially use dynamic brake to control the speed or at least stabilize it. I aim for about 5 - 10mph below the speed limit to give myself leeway. 2. When you want to add train brake, do so. Again, you generally want minimum application, otherwise you can find yourself coming to an unintended stop, at one point I put it to 30% and found myself running out of momentum. Leave your dynamic brakes where they are, no need to adjust them at this point. 3. Set independent brake to bail off. I hold it there for a couple of seconds. You will hear the dynamic brakes starting to kick in again. 4. Adjust dynamic braking to hold / adjust to the speed you want. 5. At some point you will need to release the train brake or you will stop. You can see from this picture that I was always pretty comfortable in the mid 40 mph range and was able to hold that with the dynamic brake between levels 2 and 5. The dip in the middle was where I added train brake to minimum application and lost significant speed and had to release it and then the next time I applied train brake again to minimum application was right at the end for the major slow down. The route was a pretty constant downhill with a few very short flat or very slight uphills. Hardly needed the throttle at all once I got up to speed. [For reference this was the U-LACHOU6-06 Oil Train from Los Angeles to Houston - Barstow to Victorville timetabled for 42 minutes]
Great instruction by Chloe. You can also SLOWLY reduce your dynamic down to 50% or more SLOWLY down to 20% or zero if you are confident that you'll need the brake. You can use dynamic to control the speed but don't zip out of it as the locomotives running out can cause your knuckle's/buffers to pull out. Not sure this can happen in game. In the 90s American freight trains did experiment with EP brakes and they are so good and easy to drive with, you don't need to consider losing air brake pressure. But they aren't used generally these days unless someone can tell me. Just as we see in game. When I get a 3% grade and the train is heavy like grain, you'll need more air brake. Not just minimum. Down to 70PSI. If you haven't got your dynamic or air brake on and you are doing 30mph you are asking for trouble. By 22mph when your speed starts increasing you should be looking at going to full dynamic. and if you reach 25-28mph and it still increases then a minimum application is a must.
Even in the SD40-2, you should bail off the loco brakes. ALWAYS bail off even if the dynamics don't cut out.
In reality, BNSF wouldn't be sending trains down track 1 and the 3% percent grade if track 2 and 3 are available, especially not the heaviest of their freight trains.
I have tried the above suggestions and nothing seems to work to bring the dynamic braking back once I put pressure on the auto brake or the independent brake. I have tried it all ways I can think of, the train runs away each time. I throw the emergency quickly and it will recover if I apply power at 10 MPH to keep it rolling. Not a good train driver here. I am using a Saitek throttle and CobraOne's driver, have calibrated it numerous times. The throttle and brakes seem to work fine, so I don't think it's that. It's me. Me and the G-HOULAC6-07 Grain Train don't get along.
You're suppose to hold the independent brake in bail off if you are applying auto brake so that the dynamic brake can work at the same time
US freight is a different beast than everything else in the game. A few things that have worked for me: 1. Don’t try to be going the speed limit downhill. If you’re targeting the speed limit you’re going to lose it. Keep it around 25mph. 2. Use blended braking. That means you want the automatic brake set to something that won’t be slowing you down but will keep acceleration under control. Then use the dynamic as the “fine tuning” to keep you around that 25mph. Usually that means automatic brake in minimum reduction but it will vary between grade and train weight. 3. Don’t forget to bail off the independent every time you add automatic brake. Also try not to be messing around with the auto brake too much. You should set it as you’re cresting the summit of the hill and not need to mess with it much as you descend. The dynamic should be the one you’re playing with on the way down. So to summarize, as you’re cresting the hill, set the automatic brake to minimum reduction, bail off independent. Then monitor your speed and try to keep it around 25mph using the dynamic. If you’re having to max out the the dynamic to do that, maybe add a bit more automatic. If the automatic brake is slowing down the train WITHOUT the dynamic, you have too much automatic brake.
^This. To reinforce an important point, don't set the auto brake, then release, then reapply - it takes a looooong time to recharge once released. And don't wait until you're already in freefall to go to it; it also takes a long time to grab. Incidentally, dynamic brakes are at maximum effectiveness at ~30 mph. Friction brakes, however, lose effectiveness as a direct function of speed (which is why when Saluda Mountain was in use, they went down at 8 miler per hour!) Common rookie sequence: wait until train is completely over the crest and accelerating through the line limit. Set dynamics. Dynamics aren't slowing it down, go to 100%. Still not holding, apply minimum reduction. Train does not immediately slow, add 10 or 15 pounds. Air starts to grip, train slows to a crawl. Release air brakes, repeat sequence- except this time the air isn't as effective. Third time through the order there is no air at all, and you either have a runaway or a panicked grab for the big red button. (Don't ask me how I know this)
Something is escaping my understanding there. How can the air brake loose effectiveness? Is that because the system is over-pressured? But when I look at my air gauges, even the end of train air pressure never goes beyond 90 PSI.
Are you sure you mean that timetable route? It's uphill all the way - great for getting throttle control. Only time you need to brake is at the summit at the end of the route, and no need at all for dynamic brake. Try the timetable route that I mention in my previous post (#17). It's pretty easy and good for getting used to controlling speed with the dynamic brake as well as blending in the train brake a little.
There are two elements involved (and a third which the game doesn't model, brake fade): 1) friction brakes are most effective at a dead stop (this is why a handwheel will hold a parked train), and lose effectiveness as the vehicle speeds up: the same amount of pressure provides less and less drag force to slow the train down. Therefore really heavy trains take steep downgrades quite slowly. 2) Loss of air: every time you release the train brake, all the air that was in the cylinders is vented to the atmosphere. It takes the compressor/main reservoir a good long time to replenish the lost air and refill the length of the pipe (which could be over a mile)- think how long on pre-patch Sherman Hill it took to charge they system. Note also how long it takes to top off just one car tire up to a mere 35 psi! It is possible with repeated applications before the system is recharged to "run out of air" - and then you're well and truly screwed. (Note that if you have a trailing loco, the End pressure will always read 90, because it's filling the pipe from the back as well. But the cars in the middle...... This is one reason DTG needs to implement working airflow meters on all US locos)
It's a phenomenon peculiar to triple-valve air brakes. When the brakes are released, the brake pipe is fully charged, and the auxiliary reservoir is charged through the brake pipe to that pressure. Every time you apply the brakes, the brake pipe pressure is reduced, and the auxiliary reservoir is discharged into the brake cylinder until it matches the new brake pipe pressure. When you release the brakes, the brake pipe pressure is increased, and the brake cylinders are discharged to atmosphere as soon as a noticeable increase is noted at the wagon. But because air has to flow through the pipe to bring both the whole pipe and every auxiliary reservoir on the train back to normal pressure, it takes a long time to get back to the fully charged condition, all while the brakes are in fact released. If you apply the brakes again during that process, you're applying them to a system that isn't fully recharged, and the brakes will be less effective as a result. If you keep doing that repeatedly, eventually you'll barely be able to apply the brakes at all, even using the Full Service position on the handle. At this point you have "run out of air" and the only recourse is to apply (and keep applied!) the Emergency brakes. Once you have stopped in Emergency, you'll have to find a way to hold the train still on the hill while you wait for the system to recharge from nothing. In other words, start applying handbrakes. This is another area where European trains have solved an important problem; they use distributor-valve air brakes rather than the (obsolete for a century already) triple-valve type. This means that brakes only release fully when the brake pipe has charged fully, and it is substantially more difficult to "run out of air", especially since the valve is able to partially recharge the auxiliary reservoir even with the brakes applied (to compensate for leakage through the brake cylinder). In the dual-pipe system, the auxiliary reservoirs are also trickle-charged by a second pipe down the train, so releasing the brakes only has to charge the pipe, not the reservoirs, which is much faster.
Dang! I feel so dumb to not having thought about this myself . Thank you for your answer, it's much clearer to me now. Ok, I think I got it. So when I was going in the 3% downhill grade with my 14500 tons freight train, I had to use the auto-brake to full usage to barely keep my speed constant because my previous applications of the auto-brake had the EQ reservoir (these are the auxiliary reservoirs, right?) somewhat depleted thus, the brakes weren't really applied to full service. What I should have done is stopped the train with everything I could (for example applying the independent brakes in addition of all the other brakes), and wait for the system to charge entirely the auxiliary reservoirs. Did I get it correctly?
Once you were in that situation, yes. Of if all else failed, go to emergency. Then after stopping hold the train using independent brakes plus if necessary handbrakes, and just wait until the system recharged completely. Next time, apply the train brake once and don't release it until you reach the bottom! (Helpful hint- a triple-valve system, once set, cannot reduce pressure, only increase. The only way to reduce pressure is to release and re-set, which as above is a Really Bad Idea. Therefore reduce BP pressure a little bit at a time and let it take hold, don't shove in a 20-pound reduction all at once because then you'll have no choice but to release)
Found a very well made explanation about the whole system. It lacks pictures, but it's helpful for people like me who don't know very well how those brakes works.
The whole train needs handbrakes applied. It is called tying it down. Then recharge completely. Then make a minimum application when charged. Release handbrakes. Then use power to accelerate.
What loco are you all using? On my ES44 the bail off on the independent brake does nothing but set independent brakes. I've tried calibrating it again and again. - Using dynamic brakes up to about 20 mph - When the speed is picking up past 20MPH set the Automatic Brake to ~30% and bail off the independent. - Dynamic brakes drop to zero and never recovers. It shows either 90% applied when at the top bail-off, and 10% when in lower bail-off. Never says "Bail Off" or anything else and the dynamic brake does not come back. When I press Bail Off key '[' it does does the same thing as moving my lever a notch, it does not reset dynamic brakes. Is there another switch to throw or valve to close that I am missing? This is the Cajon Pass Journey Ups and Downs "G-HOULAC6-07 Grain Train from Houston to Los Angeles" scenario. It is all downhill at up to 3%.
I want to learn this, getting desperate enough to watch YT videos. I saw this fellow do it Mine won't do that. The bail off doesn't do what his does. I may try without the joystick driver and go keyboard only to see if that's doing it to me.
I got it finally. Sorry to be such a bother but I learned a ton. And it jolted up some good conversation. My issue was due to my reliance on the throttle/brake/ind levers with very little keyboard input at all. Basically, I didn't realize how to bail off. My levers do not perform the bail off function.
The bail off animation shows the lever being pulled down. Maybe you have to do that with the mouse to bail off. I use the keyboard for acceleration / braking, because I want to keep an eye on the tracks when I'm pushing them, so I can't tell you better
Right, the animation is what doesn't happen with my levers. But pressing '[' for a second or more does the bail off, or mousing it works. Now that I know, the rest is just time in cab. I prefer the levers (Logitech throttle quadrant) over keyboard but driving that mission with keyboard was a nice experiment to help figure things out.
The real challenge start when u use brakes like IRL = MAIN permanent dynamics + SUPPORTIVE correctional/periodical autobrakes (IRL autobrakes would overheat and burn if used permanently downgrading
I have never heard of Distributor valves. Germany uses it? https://www.railairbrakeparts.com/distributor-valve It makes sense though for steep grades, especially in the Alps of Switzerland and surrounding areas. I can see how it could be engineered to release only when the BP is charged to full pressure ie 500 or 700kpa. Australia and UK uses 500kpa. I think the USA is the only country to use 700kpa or 90Psi.
Distributor valves are the UIC standard for air brakes - which applies throughout Europe. I think even the ex-Soviet railways use them. Once you have mass-production set up, they're just as economical to manufacture as triple-valves plus all the gubbins added to make triple-valve brakes halfway viable. The Kunze-Knorr brake valve was the first commercially successful distributor valve, invented just before WW1 and a wholesale fitment programme instituted just after WW1. This early type did not have the feature of replenishing the auxiliary reservoir from the brake pipe while the brake was applied, so it was still possible to "run out of air" on long descents, due mainly to leakage from the brake cylinders (which would be made up from the auxiliary reservoir, so long as there was still air in it). Steam locos were fitted with reciprocating air pumps with relatively limited capacity, and in mountainous areas were sometimes also fitted with exotic dynamic-braking systems such as the counter-pressure brake, partly to mitigate the limitations of both triple-valve and Kunze-Knorr brakes. By the time diesel and electric traction became really viable, more advanced versions of the distributor valve became available, rectifying the leakage problem (by recharging the auxiliary reservoir at every normal state of the brake pipe, from Released to Full Service inclusive) and improving braking performance for express passenger trains. It was this type that was adopted in Britain after steam traction was eliminated, British steam locos having standardised on vacuum brakes instead. Triple-valve brakes became an acknowledged special case in the British operating handbooks, applying only to "Continental wagons" crossing the Channel on ferries from France, and also the standard type of slam-door EMU which had a triple-valve brake as a failsafe backup for the primary EP brake. All newly built British freight wagons from the mid-1970s onward adopted the distributor valve. I mentioned the dual-pipe air brake system which offers a second method of recharging the auxiliary valve, such that this duty is mostly eliminated from the brake pipe. This system is typically fitted to passenger stock and intermodal wagons, as due to their higher permitted speeds they need a faster brake response, especially since intermodal trains tend to be relatively long due to their low mass density. The second, MR pipe is typically kept at 7 bar while the brake pipe is nominally 5 bar for release, 3.5 bar for full service braking. Hence in the normal condition, the auxiliary reservoir on each wagon is charged to 7 bar and the control reservoir to 5 bar. Having the correct reference pressure in the control reservoir is vital for correct operation of the distributor valve. However, the actual pressure in the brake pipe varies slightly between locomotives and along the length of the train. So this pressure is not set at the factory, but is instead calibrated at train formation by performing an overcharge cycle. The brake pipe is overcharged slightly beyond the normal release pressure, then reduced back to the normal value very slowly, during which the distributor valves remain in the Released position which keeps a very small valve open to the control reservoir. This is normally done with the train at a stand with the locomotive brakes hard on, and sometimes wagon handbrakes as well. The process takes several minutes; failing to do it can result in dragging brakes.
As far as I understand, there's one very good reason to use American-style breaks over European. And that's the length of trains. European trains brakes will only fully release, when brake pipe pressure goes back up to 5 bar. For European 300-400 meter long trains it's not a big problem. Yes, it still takes awhile for brakes on rearmost cars to release, but that time is not excessive. But if you use this type of brakes in 1.5-2 km long trains, you'll end up with brakes that take several minutes to fully release. Besides, release will not be uniform -- you will have no brakes at the front, while still having close to full application at the back, which will create additional strain on the couplers. One of the ways to mitigate this problem is to have both types of brakes in one system. For example, ex-Soviet countries, which have cargo trains of 50-100 wagons (5000-10000 tons), use distributors with two modes on their cargo equipment (current model is type 483 distributor). It has a Flatland Mode and a Mountain Mode. Flatland Mode works the same way as American brakes -- you can only release fully, but that release is fast and even throughout the train. And Mountain Mode is the same as European brakes -- more sluggish response and uneven release times through the length of the train, but added safety from running out of air on the descent. So, if train goes on the line with grades smaller than 1.8%, it will use Flatland Mode. If grades at at least one point of the route are 1.8% or higher, brakes will be in Mountain Mode.
The High Output Ballast Cleaner is reportedly 800m long (that is, half a mile), and includes 20 wagons to supply new ballast and another 20 to receive old ballast. The intermodal trains carrying Tesco's logistics around Britain are about 750m with the locomotive, carrying 40 large shipping containers. The heavy stone trains, operating under various names over time, and generally hauled by the Class 59 (an American product) are up to 640m long and regularly weigh in excess of 5000 tons. These trains all work just fine with distributor brakes, including going up and down Shap and Beattock, which are about as severe a challenge as you'll find on a British mainline. They use the dual-pipe system to improve the brake response time, and the intermodal trains may run at 75mph. A test train of more than double that length and weight was trialled, with the main problem being buffer-locking of the mid-train locomotive (a very unusual arrangement for the UK) with the wagon immediately ahead of it, which it was pushing, which resulted in a coupling fracture. It appears that the performance of the braking system in this "mega train", though noticeably slow to the driver, was not a factor in the results of the trial, even though the train was more than a mile long. It is of course recognised that long brake pipes are slow to react throughout the train. The European solution to this is to provide wagon brakes with two "timing modes", typically labelled P and G. In P mode, the distributor valves react to changes in brake pipe pressure quickly, and can fully apply or release the brakes within a few seconds. In G mode, the passage of air to or from the brake cylinders is deliberately restricted, so that full applications and releases take tens of seconds. Consequently, braking forces are reasonably even throughout the train at all times, but the slow response limits the permitted speed of trains using G mode. However, the dual-pipe system allows the use of P mode even with 800m trains, because the brakes respond quickly enough when the brake pipe isn't doing double duty. The permitted speed of trains is then more likely to be limited by considerations such as axle loading and the ratio of total brake force to train weight. G mode is typically used with wagons fitted only with the single-pipe system in relatively long trains.
That' hardly even places by American standards, where in 2017 the average freight train was 1.3 miles (2100 m) long and weighed 19,000 tons, and where the Liffey Incline would rate as a speed bump. ______________________________ 90 psi is for freight trains. Passenger trains run at 110 psi (750 kpa)
One more thing to consider is the fact that American and ex-Soviet railroads use automatic couplers (and of pretty old design at that), which have more play than European screw couplers. And their looser connection causes more longitudinal forces in the consist, when brakes release unevenly. That might also be a factor in why partial release distributors aren't used in USA. Speaking of uneven release. Today I learned that Russian type 483 distributors actually have fancy automatic (though, purely mechanical) system that changes the rate of release based on the location of a car in the consist. Basically, it does the same thing as G/P setting on KE brakes, but automatically and smoothly based on the rate at which brake pipe pressure goes up. The slower BP pressure rises, the faster air is vented from brake cylinders, and the other way around. So, the further down the train you go, the slower BP pressure rises, which, in turn, causes brakes at the end of a train to release faster, reducing longitudinal forces. By the way, KE-GPR brakes were and still are used on some Soviet and post-Soviet equipment. Mainly, on passenger cars that go to Europe. Why they were never used on the stock for internal use, I have no idea. But, I guess, they had their reasons.
After a month or two being busy with American Truck Sim & Euro Truck Sim 2, i jumped again to Cajon Pass and did few runs on a 14.5K tons Grain & Cement trains. I certainly still "got it". Remember to actuate your independent brake in every BP reduction you make & control your speed using the dynamic. The challenge is to not use 100% dynamic and full service automatic brake while still have the train in control. I usually do 25 mph in the steepest part of the route.
Suryaaji#2369 As max#2873 said, "IRL autobrakes would overheat and burn if used permanently downgrading" I have been using between 25% and 80% auto brake along with the newly acquired talent of bailing off and using dynamic braking. This is surely wearing out the brakes on a 15 mile downhill ride. I wonder who pays the bills... I don't know how one can only use periodical auto brake. Has anyone mastered that?
It is absolutely fine to have autobrakes engaged through the whole descent. Even more so, you only release autobrakes when you know for a fact that dynamic brakes would be able to keep your speed from increasing for next 5-10 minutes. Otherwise, just power through the brakes, until it's safe to release, or stop, put independent brakes on, put handbrakes on, and recharge airbrakes, while stationary. For example, CSX employee timetable requires all trains going through Sand Patch tunnel towards Cumberland to have at least minimum airbrake application all the way from the tunnel to Hyndman. That's 17 miles. And when grade temporarily becomes more shallow, it tells to reduce dynamics, and, if necessary, add power to pull through airbrakes, but never tells to release airbrakes. Also note, how it requires engineer to apply airbrakes even before reducing throttle. Here's a quote from timetable: "As train crests grade continue to use power and make an initial application of 5-7 PSI between 20 to 22 MPH. Then gradually reduce throttle and apply dynamic brake in such a manner to have speed between 25 and 30 MPH, passing BF208. MP BF208.0 to BF202.1 – In the vicinity of MP BF207, train speed will gradually increase due to the heavier grade. When this occurs make additional light brake applications if necessary, modulating the dynamic brake to hold speed between 32 and 34 MPH, between MP BF207 and BF202.1. MP BF202.0 to 191.1 – Approaching MP BF202 the grade becomes less severe and the speed restriction at BF202.1 is reduced from 35 MPH to 30 MPH. Therefore, watch deceleration rate very closely, and apply power if necessary to keep speed between 20 and 30 MPH between MP BF202 and MP BF198.0. In the vicinity of MP BF197.0, grade again increases and train speed will generally begin to increase. If this occurs, it may be necessary to apply dynamic brake, or to make an additional light brake application in order to maintain speed at 30 MPH. This speed should then be maintained by modulating the dynamic brake or throttle to Hyndman MP BF191.0. Then if conditions permit, release train brakes and handle train in accordance with good train handling." Basically, you need to have just enough airbrakes, so that this reduction plus dynamics on positions 4-5 would keep the speed stable. This way you can modulate your speed by changing dynamics. If you got to 7th position of dynamics and train still accelerates, add some more air. If train decelerates with dynamics off, then you have three options: 1. If grade is shallow enough, and will be shallow for considerable distance, release airbrakes and control speed with dynamics. 2. If grade is too steep for a safe release, you have one of two choices: a. add power to pull through brakes until it's safe to release, or until grade becomes steep again b. stop, secure the train with loco brakes and handbrakes, recharge, and then continue descent P.S. BNSF also requires usage of autobrakes on all relatively heavy westbound trains going over Cajon Pass. Here's a quote from employee timetable: "The speed of trains must be controlled, at least in part, with the automatic air brake when the train tonnage exceeds: 2,500 tons on Main 3 between MP 56.6 and MP 61.5 or 3,500 tons on Main 1 and Main 2 between MP 56.6 and MP 78.0, and Main 3 between MP 61.5 and MP 78.0." So, airbrakes should be engaged for 21.4 miles on anything heavier than 3500 tons.
I'm using this video as my basic of understanding. It's certainly okay to leave the autobrake applied all the way down to the foot of the pass if you use it correctly (and not overspeeding the train). If my memory serve me well, it's actually against BNSF rules to release the autobake on the fly while negotiating a downgrade run. Well, if we can't apply the autobrake all the way to the bottom, how about the days of steam in the past when the only available braking option was automatic brake.
What he means is, when the brake is applied and released but isn't given time to recharge fully, the effectiveness of the air brake is reduced due to lower pressures. I'd like to know more about distributir valves. I thought the Westinghouse system originated in the UK? I think the Distributor valve is actually based on the triple valve. Is there any more material on the Distributor valve on the web? I have done a full air brake training module and we only use Westinghouse and vacuum (vacuum is 1950's-1970's vintage). I understand there is EP braking too and that railcars use similar type brakes to locomotives. I thought the UK used Westinghouse triple valves.
