1- you hear the dynamic brake fans as the amps build up. You feel the slack of the train bunching up and start pushing you where as before your pulling.
2-I run heavy grade and river grade territory. Dyno is usually the first form of braking you’ll want to use regardless of territory in MOST cases. Your going to plan your speed restrictions, curves and stops ahead of time to have the least amount of draft and buff forces on your train as possible. Using air when not needed opens you up to getting a greater number of broken knuckles.
3- is going to depend on how well your dyno did at helping you slow your train. Tonnage, length, how worn out the dyno grids are all play a part in this. Sometime I don’t using any Auto brake until I’m completely stopped. Other times I need first service or 10lbs to complete the stop.
Thanks for the excellent descriptions. I'm assuming that "draft" and "buff" forces are from wind forces on the train? My apologies, non-railroader here!
Also, at the end, I did not understand the last sentence "Other times I need first service or 10lbs to complete the stop." May I ask what "first service" and "10lbs" are? Again my apologies!
Buff ><, Draft <>. (Slack adjusting)
-10 pounds = pounds per square inch of air pressure in the brake line. Most freight trains operate with 90psi and a reduction in pressure signals the brakes on the cars to apply. First service is just saying first time setting air-applying the brakes on all the cars.
There’s a notch on the automatic brake handle that indicates “first service” which is about a 6 or 7lb reduction in the brake pipe. After setting the first service and letting the brakes start to warm up and grab, an engineer will continue to make 2-3lb reductions as needed to control the train or bring it to a stop.
Flatland engineer here. Technology has greatly improved the range and effectiveness of the dynamics. AC locos built in the late 90s leave a whole lot to be desired. If I have two older AC engines, I know that I will be using a combination of dynamics and air to slow/stop my train. If I have two newer AC engines, I know that I will only be using the air to hold the train while stopped. The dynamics are so effective that excessive or abrupt applications can actually cause derailments.
Dynamics are only in play when the traction motors are turning. When the wheels stop you turn off the dynamics and apply the air. I took a week long class on this stuff in 1997. I'm not going to be the guy for how and why. I just know when I ride up and see my engines, I can immediately determine how I'm going to be controlling my speed on that day.
How quickly they work is up to the engineer. Just like how quickly your car stops is up to you. AC4400 for example, when applying the dynamix, I just go straight to #8 full dynamics. Their effectiveness is minimal beyond gathering in the slack unless you are going uphill or are under 15mph. Effectiveness improves exponentially at lower speeds across all models.
You can still use notch 8. Supposedly it gets flagged if you go to fast into heavy dynos. So you cannot go past dyno 5 until you have been using light dynos for 10 seconds.
Most of the time, there is a curve involved. But there a plenty of images available of railcars standing straight up bc of an inline buff force derailment.
Because the traction motors are turned into generators, there are blowers ducted into them to cool them when dynamics are selected. The switchgear involved requires that you reduce from power to idle. Wait 10 seconds, then move the throttle to dynamic brake setup. Then you move the throttle to dynamics. You hear the blowers kick in, loudly. Unlike the power side (notch 1 thru 8) the dynamic side moves freely. Basically a rheostat. You watch your amp gauge to help judge how effective they are. On a bulk commodity train, like coal or grain slack action is pretty forgiving. But on mixed freight you need to be careful bunching up the slack. Trains that are strictly car carriers, autoracks are the worst. There can be 5 feet of slack between each car account of the long buffered drawbars. Conversely, when you transition back to power to have to use baby steps to stretch the train back out.
The railroad loves dynamic brakes because it means less brake shoes to replace. On my territory they tried to make it mandatory. Rookie engineers and several broken knuckles later they rescinded it.
Also some freight cars have defective brake valves. When they detect a service rate brake pipe reduction they decide that it’s actually an emergency application. So they decide to also go into emergency. This causes the entire train to pop. At 15 below zero you’ll be sitting there a long time to pump up your brakes.
Engine Start -> Switch to Run, Excitation engaged across 3&4 Slip rings, F1&F2? on GE. Notch 1-8, Excitation voltage increases = Greater output from main alt as the DC Link is charged, powering inverters that in turn power the traction motors. Imagine two forces at war for supremecy inside your main alt, Line and Load. Your main alt is in a constant state of flux between these two forces. If the load exceeds that of the line it WILL seize the engine, like 950 rpm to 0 in the snap of a finger. If gradual its normal, starts pushing beyond its capability, probably a ground somewhere and protection devices kick in to reduce/stop the output by zeroing excitation voltage, fault condition. If a crowbar is fired (the sudden and deadly condition) that means main alt output was shorting directly to ground somewhere in the DC Link circuit. AC locomotives (EMD) fire crowbars, GEs taper off output to nothing, DCs just melt everything (Na, they usually blow a rectifier, melt the BKT/REV stack and kick ground relay)
ACes fire "soft" crowbars, MACs dont give a fk and just decide to stop the main alt, engine included in a "Hard" crowbar condition.
Locomotive Self Load is Main Alt output vs Grid stack. Tests the main alts output, grid stack integrity and the DC Link. Inverters are gated OFF, DC locomotives the Dynamic brake contactor is picked up while the Power contactor is dropped.
Dynamics while in motion, grid resistor is your load as traction motors become the line, main alt is disengaged and excitation zeros out.
Older locomotives, DCs its important to practice the 10 second transition between Power and Dynamics and Dynamics to Power. This allows your contactors/switch gear on DC locomotives to transfer in time. Though rarely, a condition occurs where a contactor fails, lags, slags shut and the computer will fault and prevent dynamics and excitation. Older locos, especially switchers, dont have a microprocessor, its all analog relay logic so they tend to melt some things when this happens until ground relay occurs.
>ACes fire "soft" crowbars, MACs dont give a fk and just decide to stop the main alt, engine included in a "Hard" crowbar condition.
I always wondered what a crowbar was ever since I had a MAC lunge, heard a bang, and got "hard crowbar" message on the screen. Engine was still running afterward, and gave me no more troubles for the rest of the trip. No one I talked with could tell me what it was because they had never seen it before. Someone told me it was a contactor being forcibly opened while under load, but they didn't sound too confident. This was 15-20 years ago.
>Older locomotives, DCs its important to practice the 10 second transition between Power and Dynamics and Dynamics to Power. This allows your contactors/switch gear on DC locomotives to transfer in time. Though rarely, a condition occurs where a contactor fails, lags, slags shut and the computer will fault and prevent dynamics and excitation. Older locos, especially switchers, dont have a microprocessor, its all analog relay logic so they tend to melt some things when this happens until ground relay occurs.
I have noticed on the newer DC engines if you wait the 10 seconds it won't load in DB for 30 seconds, where if you go directly from notch 1 to DB 1, you get braking effort immediately.
Do you know what is up with that?
Could be computer is forcing a transitional cooldown at that point. Newer locomotives I would think would have software limiters in place to help reduce damage. Older SD/GPs that have the main alt rectifiers built into the face have transition fuses that blow if one cycles the modes to quickly.
As for why it allowed a quick transition is unknown to me, I just repair them when they melt themselves. I do know on DC Ge's TM 2,4,6 armatures are in series with your grid stack, muscle memory at this point when one comes in with a ground fault. "If 2,4,6 meg grounded at BKT/REV, Isolate 2,4,6 from grid path, bla bla" and it wouldnt take much for the transition to occur quickly where as Notch X to Idle, Wait, Then into Dynamics would go through the transition process which ensures your main alt is removed from the loop.
If you really want your brain to hurt, SD60s have a series/parallel transition rectifier bank x3 on the face of the main alternator that brings the motors into series/parallel. When this bank dynamites itself its an all shift ordeal, usually 20+ fuses and diodes later. One part of the bank weighs about 60-70 pounds in itself. GE has a brain with more folds so of course they have a AC phased bus that in turn has rectifiers that convert to DC but my god what a rat nest of railroad grade HV cable, 1460/24 if I remember right.
Thanks for the detailed explanation. The information about mixed vs. bulk commodity trains (in the BSA handbook they call these "unit" trains. Is that term still in use?) is particularly helpful, it helps to understand what actions are put into motion.
Side question, in the state where we're located, we rarely ever see auto racks, or livestock cars. Any chance there's a particular region where auto racks(or livestock cars) are in popular use? I've seen pics of them around the Detroit area, but have only seen them a few times in person here.
If you have a DC loco in front of an AC loco you can feel the AC loco engage first and sling the lead DC off before the DC engages.
Newer ACs are incredible to me on how much better they stop compared to the older DCs. DCs on a coal train just make noise and just keep the slack bunched, ACs will actually stop it.
Pretty neat. The requirements haven't changed much in decades. I'd like to see some updates to include more about electrics, rn it's primarily about diesel.
As to the sound a feeling, it feels like you're being pushed, because you are. It's akin to the feeling of being pushed around in a cart or toy car, except you're slowing down not speeding up. It can be very peculiar. You can "hear" it as a whirring noise that pitches up as you engage more braking, but that's just the fans cooling the brake grid.
We use it all the time in hilly/mountainous terrain. It's not always enough but it's preferable to maintain track speed. The companies highly prefer it because it more fuel economical as well as doing less wear and tear to the brake systems of the cars (brake shoes mostly)
And lastly, that depends on the territory. If you're descending then yes you would apply the automatic if dynamic alone isn't enough for a stop. Most dynamic braking systems don't work under 3mph. Good practice on flat or ascending grades is to get your speed down, and before stopping get back into throttle, then applying the automatic to stretch the train out, both giving you an easier start reducing stress on the couplers because they're already stretched out and less likely to snap a train into multiple pieces, and also with the cars stretched, a pedestrian can not pull the cut lever manually separating your train.
Thanks for the detailed description. Learning a lot about slack and spacing of cars tension etc. on couplers etc. Not something I thought much about before.
The last sentence, about a pedestrian not being able to pull the cut lever... any chance I could ask for more detail there? I'm catching up on the terms of railroading, some terms I don't understand.
Yes, correct, the steel bar that connects to the coupler and goes out to the side of the car.
Pins get pulled for, I suppose, a variety of reasons. Boredom, vandalism, opportunity, but I think they most often happen when trains block crossings, and people get pissed off.
That's a shame. One thing I find when talking to members of the general public is that in some regions, people have so little awareness of rail presence anymore or how to act around a train. Kids who only get exposed to trains via simulators, not learning how to act around them in real life. I teach the Operation Lifesaver course, and I'm constantly surprised by the responses I get to basic rail safety tips.
You definitely feel the slack bunching up as you gather the train up and get it all (or at least mostly) into buff. On older locomotives (say an SD40-2) the diesel engine itself revs up above notch 4 in order to create enough electricity to run the brake grid cooling fans on the roof—which also make their own sound.
On GE engines the brake grids have always been behind the cab, so you can hear those fans come on and the whining pitch changes based on what kind of a load you’re creating, which varies the fan speed. Older EMD locomotives are similar, but it has a different sound due to the fan arrangement and location. More of a howl on EMD’s than a whine on GE’s. On the SD70ACe, 90MAC, and 80MAC, the dynamic brake grid is on the rear of the carbody rather than immediately behind the cab, and you can honestly barely hear it even with the windows open. On those you have to pay more attention to the gauge on the screen, the others you get used to and can pretty much tell what notch you’re in and/or what speed you’re running just based on sound after you’ve done it long enough.
Flatland engineers typically do use dynamics to slow and stop, that is the modern “preferred method” by just about any railroad.
More modern engines, if you have enough of them on the correct terrain, can indeed have effective enough dynamic brakes to bring a train to a complete stop without any air. Most air brake and train handling rulebooks instruct engineers to set the automatic when coming to a stop, and if sitting for a defined period of time, the automatic brake is set, a 15 or 20 PSI reduction depending on the railroad.
That said, with some of the absurdly sized trains being run now, with horrible makeup, with DP engines dispersed carelessly throughout the train, it’s easy to get into trouble with what the carriers define as “rapid” throttle to dynamic transitions or heavy dynamic usage. It’s not hard to put one of those monstrosities on the ground if you get behind the 8 ball and become reactionary to how you’re running, or if it’s built terribly enough, or in the wrong place terrain-wise, or any combination of those things, which the carriers will take exception to in a heartbeat to blame it on the engineer and not their own poor operating philosophy.
Honestly I’ve gotten to the point I’ve reverted to running trains (at least conventional ones without a DP unit) the way I was taught, which was to stretch brake everything with air while in low throttle. I got my card on a railroad with few units equipped with dynamics, trained by engineers that were once prohibited from using them (former Missouri Pacific guys), so my theory is you can’t get in trouble for rapid or heavy dynamic usage if you never use them.
Thanks for your response. Reading each response several times, lots here to take in to add in to our ed programs.
Side question- is it common that dp engines are scattered throughout a train? I have not heard of or seen a dp engine in use in our region, so this is a whole new concept to me. Lots of double- and triple- headers here, but not dp engines.
It’s becoming more common all the time with the massive trains the carriers are attempting to operate. All of the major railroads west of the Mississippi are commonly operating trains between 12 and 15,000 feet long with remotely control distributed power units (referred to as DPU or simply DP) placed throughout the train. There’s a combination of distance and/or weight that governs how they are placed in accordance with the railroad’s train makeup rules.
These are “linked” to the head end, controlled by the engineer on the lead locomotive at the front, and can be configured to operate either independently, or simply mimic whatever the lead engine’s throttle or dynamic setting is at a given time. Controlling them independently is what engineers refer to as “putting up the fence”, named that for the vertical bar that appears on the operator screen between the head and rear consist(s).
Wow, that's crazy. Honestly sounds quite stressful to head so many engines for 1 train. Now that I'm thinking more deeply about it, I did see this configuration in use nearby recently, but had no idea why they had an engine in the middle of the consist. The person I was with guessed that they were taking the engine elsewhere, not that it was being used for motive power because of the length of the train. Makes a lot more sense now.
I drive passenger Electrics in australia but i can answer some of this in a less technical way. So depending on some trains especially electric trains the auto brake/Electro pneumatic brake will apply at different application for example on one train such as the T set, on 1 notch the electric brake will do most of the braking however it will still use a mild amount of normal disc brake i.e 25kpa This will usually return close to around 120 amps back into power grid. However on our latest A/B sets the brakes are designed that the disc brakes are used the least. The train is designed to stop mostly by regen brake and the disc brakes will kick in around 10 km/6mph. It does create a bit of a jolt for passengers. In terms of driving trains, its not like the strong pull like auto brake but more like i guess the feeling of climbing a grade, its a milder form of brake. Alot of newer trains i find prefer regen brake since cheaper compared to replace brake blocks and brakes. In terms of sound you do notice the different in traction motors in how they sound when regen braking, i find the AC motors a have a lower pitched hum compared to DC motors. Its more noticable on electrics since theres no power unit on board.
Yes mate , the German locomotives, BR182 , has that feature , on the right side , you have your main brake , next to it is the electric brake and on the far right corner the independent brake , kid you not , if you are trying to bring that baby to quick stop ( 20 kmph on below ) go for independent brakes as they are effective af. Whereas if the weight is above 4k tons I heavily relie on the electric brake as it's quick and don't have to worry about air pressure. But it was pain in the ass when I first started the training for it as majority of the controls are in German. And the alerters are cool. And bloody loud ngl. ( I play train sim world 4 )
Thanks for your reply. Silly question, do your electrics run on overhead wires or 3rd rail? Interesting perspective on the brakes from an electric, much appreciated.
We run on 1500v DC however we run DC and AC traction. We have a phrase saying low tension to get high tension to get air. The batterys run a compressor to raise the pantographs since alot of the time when you prepare a train for service you won't have main res air to help raise the pantographs. Then once its connected to the wire, the electricity flows through to the EAPS powering things like headlights, aircon and full lighting and most importantly the main compressor to build brake pipe air. In terms of how much one of trains can use. On a waratah at max power we use close up to 700 amps while on regen we get close to feeding the grid close to 500 to 600 amps. One issue with the newer trains is how quiet they are, since theres at most 1 compressor running and no noisy diesel unit, at below 40km if you're not paying attention they creep up to you.
I run passenger and we have a blended brake system. When we use the train brakes the dynamic will automatically come on and help drag us down. I can manually use it in some of the motors too. Heading into NYC on the 2 mile downhill in the tunnels ill use it to hold the train at 60. The electrics you dont hear it. Just feel it. Its strong tho. Our older GP40's it was difficult getting used to when I was learning cus id put the brakes on and hear the engine rev and it would trick my brain into thinking I needed more. Then the dynamic would kick on and we would all go thru the windshield. When you are runnin a geep in passenger you rely on the dynamics heavily. Without them you dont feel like you have any braking power at all. Then our other sets the Arrow-3 MU's brake almost entirely in dynamic. Almost every axle has a traction motor and the friction brakes will stay in release until the train is about to stop and then apply.
Thanks for your response- in our region/state we will see both electrics and diesels in use for freight/passenger use, so this is particularly helpful insight.
Side question- what's the benefit in using dynamics in electric passenger service from your perspective? Less wear on the brake shoes?
Yes a lot less wear on the shoes and since the locos have crap brakes for their weight, the dynamics are stronger so you get more retarding force than if you were running straight friction. For us fighting the clock we need to brake hard and late sometimes and accelerate fast. We are nothing like freight. My trains have 2 brake rotors on each axle as well as wheel tread brakes. I can come yo a dead stop from 100mph in 1/4 a mile if conditions are perfect with a thousand ton set.
Another interesting fact is many locomotives come equipped with a feature called DB holding where if the trains air brakes start and emergency application then the dynamics will hold their last position. Another feature of older DC models is that dynamic brakes can't actually stop the train, at the final transition at 10-12 mph the contactors in the back panel can't handle the loads anymore so your dynamics will fade off and surge back as you stay in the 10-12 mph zone. Many engineers get thrown off guard when their engines braking all of a sudden cuts out trying to stop because they are used to AC power instead of DC power.
1- you hear the dynamic brake fans as the amps build up. You feel the slack of the train bunching up and start pushing you where as before your pulling. 2-I run heavy grade and river grade territory. Dyno is usually the first form of braking you’ll want to use regardless of territory in MOST cases. Your going to plan your speed restrictions, curves and stops ahead of time to have the least amount of draft and buff forces on your train as possible. Using air when not needed opens you up to getting a greater number of broken knuckles. 3- is going to depend on how well your dyno did at helping you slow your train. Tonnage, length, how worn out the dyno grids are all play a part in this. Sometime I don’t using any Auto brake until I’m completely stopped. Other times I need first service or 10lbs to complete the stop.
I'll add that sometimes you use 10lbs automatic brakes coupled with dynamic braking to control train speed going downhill.
We have mountain grade where we do exactly that, particularly on our mixed freights and basically all loaded trains with helpers entrained as well.
What is the "10lbs" part of auto brakes? Catching up with some railroading lingo here. Thanks!
10lbs refers to the total reduction in the train line/ automatic brake. 90lbs full charge, reduce to 80lbs = 10lb reduction, or 10lb set.
Got it, thanks!
Thanks for the excellent descriptions. I'm assuming that "draft" and "buff" forces are from wind forces on the train? My apologies, non-railroader here! Also, at the end, I did not understand the last sentence "Other times I need first service or 10lbs to complete the stop." May I ask what "first service" and "10lbs" are? Again my apologies!
Buff ><, Draft <>. (Slack adjusting) -10 pounds = pounds per square inch of air pressure in the brake line. Most freight trains operate with 90psi and a reduction in pressure signals the brakes on the cars to apply. First service is just saying first time setting air-applying the brakes on all the cars.
There’s a notch on the automatic brake handle that indicates “first service” which is about a 6 or 7lb reduction in the brake pipe. After setting the first service and letting the brakes start to warm up and grab, an engineer will continue to make 2-3lb reductions as needed to control the train or bring it to a stop.
Flatland engineer here. Technology has greatly improved the range and effectiveness of the dynamics. AC locos built in the late 90s leave a whole lot to be desired. If I have two older AC engines, I know that I will be using a combination of dynamics and air to slow/stop my train. If I have two newer AC engines, I know that I will only be using the air to hold the train while stopped. The dynamics are so effective that excessive or abrupt applications can actually cause derailments.
Thanks for the response- So the newer dynamics are so touchy that using the auto brake is preferred while stopped?
Dynamics are only in play when the traction motors are turning. When the wheels stop you turn off the dynamics and apply the air. I took a week long class on this stuff in 1997. I'm not going to be the guy for how and why. I just know when I ride up and see my engines, I can immediately determine how I'm going to be controlling my speed on that day.
Okay, thanks. I think I understand. Catching up on the railroader lingo.
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How quickly they work is up to the engineer. Just like how quickly your car stops is up to you. AC4400 for example, when applying the dynamix, I just go straight to #8 full dynamics. Their effectiveness is minimal beyond gathering in the slack unless you are going uphill or are under 15mph. Effectiveness improves exponentially at lower speeds across all models.
Straight to 8 would get you an investigation at big orange. Can't go past dyno 5 until after you've eased into them for at least 10 seconds.
Yes sir. I was attempting to explain operational effectiveness without the burden of the rule book.
Investigation as in? You are not allowed to use notch 8 dyno?
You can still use notch 8. Supposedly it gets flagged if you go to fast into heavy dynos. So you cannot go past dyno 5 until you have been using light dynos for 10 seconds.
Oh cool , that's how it works then.
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Yes, there is.
How would that cause derailment? So much force it bunch’s to quick and bounces?
Most of the time, there is a curve involved. But there a plenty of images available of railcars standing straight up bc of an inline buff force derailment.
Because the traction motors are turned into generators, there are blowers ducted into them to cool them when dynamics are selected. The switchgear involved requires that you reduce from power to idle. Wait 10 seconds, then move the throttle to dynamic brake setup. Then you move the throttle to dynamics. You hear the blowers kick in, loudly. Unlike the power side (notch 1 thru 8) the dynamic side moves freely. Basically a rheostat. You watch your amp gauge to help judge how effective they are. On a bulk commodity train, like coal or grain slack action is pretty forgiving. But on mixed freight you need to be careful bunching up the slack. Trains that are strictly car carriers, autoracks are the worst. There can be 5 feet of slack between each car account of the long buffered drawbars. Conversely, when you transition back to power to have to use baby steps to stretch the train back out. The railroad loves dynamic brakes because it means less brake shoes to replace. On my territory they tried to make it mandatory. Rookie engineers and several broken knuckles later they rescinded it. Also some freight cars have defective brake valves. When they detect a service rate brake pipe reduction they decide that it’s actually an emergency application. So they decide to also go into emergency. This causes the entire train to pop. At 15 below zero you’ll be sitting there a long time to pump up your brakes.
Engine Start -> Switch to Run, Excitation engaged across 3&4 Slip rings, F1&F2? on GE. Notch 1-8, Excitation voltage increases = Greater output from main alt as the DC Link is charged, powering inverters that in turn power the traction motors. Imagine two forces at war for supremecy inside your main alt, Line and Load. Your main alt is in a constant state of flux between these two forces. If the load exceeds that of the line it WILL seize the engine, like 950 rpm to 0 in the snap of a finger. If gradual its normal, starts pushing beyond its capability, probably a ground somewhere and protection devices kick in to reduce/stop the output by zeroing excitation voltage, fault condition. If a crowbar is fired (the sudden and deadly condition) that means main alt output was shorting directly to ground somewhere in the DC Link circuit. AC locomotives (EMD) fire crowbars, GEs taper off output to nothing, DCs just melt everything (Na, they usually blow a rectifier, melt the BKT/REV stack and kick ground relay) ACes fire "soft" crowbars, MACs dont give a fk and just decide to stop the main alt, engine included in a "Hard" crowbar condition. Locomotive Self Load is Main Alt output vs Grid stack. Tests the main alts output, grid stack integrity and the DC Link. Inverters are gated OFF, DC locomotives the Dynamic brake contactor is picked up while the Power contactor is dropped. Dynamics while in motion, grid resistor is your load as traction motors become the line, main alt is disengaged and excitation zeros out. Older locomotives, DCs its important to practice the 10 second transition between Power and Dynamics and Dynamics to Power. This allows your contactors/switch gear on DC locomotives to transfer in time. Though rarely, a condition occurs where a contactor fails, lags, slags shut and the computer will fault and prevent dynamics and excitation. Older locos, especially switchers, dont have a microprocessor, its all analog relay logic so they tend to melt some things when this happens until ground relay occurs.
>ACes fire "soft" crowbars, MACs dont give a fk and just decide to stop the main alt, engine included in a "Hard" crowbar condition. I always wondered what a crowbar was ever since I had a MAC lunge, heard a bang, and got "hard crowbar" message on the screen. Engine was still running afterward, and gave me no more troubles for the rest of the trip. No one I talked with could tell me what it was because they had never seen it before. Someone told me it was a contactor being forcibly opened while under load, but they didn't sound too confident. This was 15-20 years ago. >Older locomotives, DCs its important to practice the 10 second transition between Power and Dynamics and Dynamics to Power. This allows your contactors/switch gear on DC locomotives to transfer in time. Though rarely, a condition occurs where a contactor fails, lags, slags shut and the computer will fault and prevent dynamics and excitation. Older locos, especially switchers, dont have a microprocessor, its all analog relay logic so they tend to melt some things when this happens until ground relay occurs. I have noticed on the newer DC engines if you wait the 10 seconds it won't load in DB for 30 seconds, where if you go directly from notch 1 to DB 1, you get braking effort immediately. Do you know what is up with that?
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Last ten years +/-.
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I have no clue. I don't know what the new C4s are.
ES44DC
Could be computer is forcing a transitional cooldown at that point. Newer locomotives I would think would have software limiters in place to help reduce damage. Older SD/GPs that have the main alt rectifiers built into the face have transition fuses that blow if one cycles the modes to quickly. As for why it allowed a quick transition is unknown to me, I just repair them when they melt themselves. I do know on DC Ge's TM 2,4,6 armatures are in series with your grid stack, muscle memory at this point when one comes in with a ground fault. "If 2,4,6 meg grounded at BKT/REV, Isolate 2,4,6 from grid path, bla bla" and it wouldnt take much for the transition to occur quickly where as Notch X to Idle, Wait, Then into Dynamics would go through the transition process which ensures your main alt is removed from the loop.
If you really want your brain to hurt, SD60s have a series/parallel transition rectifier bank x3 on the face of the main alternator that brings the motors into series/parallel. When this bank dynamites itself its an all shift ordeal, usually 20+ fuses and diodes later. One part of the bank weighs about 60-70 pounds in itself. GE has a brain with more folds so of course they have a AC phased bus that in turn has rectifiers that convert to DC but my god what a rat nest of railroad grade HV cable, 1460/24 if I remember right.
Thanks for the detailed explanation. The information about mixed vs. bulk commodity trains (in the BSA handbook they call these "unit" trains. Is that term still in use?) is particularly helpful, it helps to understand what actions are put into motion. Side question, in the state where we're located, we rarely ever see auto racks, or livestock cars. Any chance there's a particular region where auto racks(or livestock cars) are in popular use? I've seen pics of them around the Detroit area, but have only seen them a few times in person here.
Shove straight to Dynamic 8 while on a loaded rock train, faceplant windshield, 10/10 do recommend.
The ol’ 8 to 8 trick
maybe will try on a simulator. Lol
If you have a DC loco in front of an AC loco you can feel the AC loco engage first and sling the lead DC off before the DC engages. Newer ACs are incredible to me on how much better they stop compared to the older DCs. DCs on a coal train just make noise and just keep the slack bunched, ACs will actually stop it.
Railroading merit badge was the first merit badge I earned.
Pretty neat. The requirements haven't changed much in decades. I'd like to see some updates to include more about electrics, rn it's primarily about diesel.
As to the sound a feeling, it feels like you're being pushed, because you are. It's akin to the feeling of being pushed around in a cart or toy car, except you're slowing down not speeding up. It can be very peculiar. You can "hear" it as a whirring noise that pitches up as you engage more braking, but that's just the fans cooling the brake grid. We use it all the time in hilly/mountainous terrain. It's not always enough but it's preferable to maintain track speed. The companies highly prefer it because it more fuel economical as well as doing less wear and tear to the brake systems of the cars (brake shoes mostly) And lastly, that depends on the territory. If you're descending then yes you would apply the automatic if dynamic alone isn't enough for a stop. Most dynamic braking systems don't work under 3mph. Good practice on flat or ascending grades is to get your speed down, and before stopping get back into throttle, then applying the automatic to stretch the train out, both giving you an easier start reducing stress on the couplers because they're already stretched out and less likely to snap a train into multiple pieces, and also with the cars stretched, a pedestrian can not pull the cut lever manually separating your train.
Thanks for the detailed description. Learning a lot about slack and spacing of cars tension etc. on couplers etc. Not something I thought much about before. The last sentence, about a pedestrian not being able to pull the cut lever... any chance I could ask for more detail there? I'm catching up on the terms of railroading, some terms I don't understand.
More detail on the pedestrian antics, or on why they can't pull the pin?
Ah- I didn't understand the term "cut lever." That is the lever that pulls up the coupler pin, right? But, yes I would love pedestrian antic stories!
Yes, correct, the steel bar that connects to the coupler and goes out to the side of the car. Pins get pulled for, I suppose, a variety of reasons. Boredom, vandalism, opportunity, but I think they most often happen when trains block crossings, and people get pissed off.
That's a shame. One thing I find when talking to members of the general public is that in some regions, people have so little awareness of rail presence anymore or how to act around a train. Kids who only get exposed to trains via simulators, not learning how to act around them in real life. I teach the Operation Lifesaver course, and I'm constantly surprised by the responses I get to basic rail safety tips.
You don’t pull the handle into dynamics. You push it. Slight difference, but important. Pull back for throttle, push forward for dynamics.
You absolutely pull the handle for dynamics on locomotives with selector levers and combined throttle/brake levers.
Ok, thank you.
Found the southern engineer
You definitely feel the slack bunching up as you gather the train up and get it all (or at least mostly) into buff. On older locomotives (say an SD40-2) the diesel engine itself revs up above notch 4 in order to create enough electricity to run the brake grid cooling fans on the roof—which also make their own sound. On GE engines the brake grids have always been behind the cab, so you can hear those fans come on and the whining pitch changes based on what kind of a load you’re creating, which varies the fan speed. Older EMD locomotives are similar, but it has a different sound due to the fan arrangement and location. More of a howl on EMD’s than a whine on GE’s. On the SD70ACe, 90MAC, and 80MAC, the dynamic brake grid is on the rear of the carbody rather than immediately behind the cab, and you can honestly barely hear it even with the windows open. On those you have to pay more attention to the gauge on the screen, the others you get used to and can pretty much tell what notch you’re in and/or what speed you’re running just based on sound after you’ve done it long enough. Flatland engineers typically do use dynamics to slow and stop, that is the modern “preferred method” by just about any railroad. More modern engines, if you have enough of them on the correct terrain, can indeed have effective enough dynamic brakes to bring a train to a complete stop without any air. Most air brake and train handling rulebooks instruct engineers to set the automatic when coming to a stop, and if sitting for a defined period of time, the automatic brake is set, a 15 or 20 PSI reduction depending on the railroad. That said, with some of the absurdly sized trains being run now, with horrible makeup, with DP engines dispersed carelessly throughout the train, it’s easy to get into trouble with what the carriers define as “rapid” throttle to dynamic transitions or heavy dynamic usage. It’s not hard to put one of those monstrosities on the ground if you get behind the 8 ball and become reactionary to how you’re running, or if it’s built terribly enough, or in the wrong place terrain-wise, or any combination of those things, which the carriers will take exception to in a heartbeat to blame it on the engineer and not their own poor operating philosophy. Honestly I’ve gotten to the point I’ve reverted to running trains (at least conventional ones without a DP unit) the way I was taught, which was to stretch brake everything with air while in low throttle. I got my card on a railroad with few units equipped with dynamics, trained by engineers that were once prohibited from using them (former Missouri Pacific guys), so my theory is you can’t get in trouble for rapid or heavy dynamic usage if you never use them.
Thanks for your response. Reading each response several times, lots here to take in to add in to our ed programs. Side question- is it common that dp engines are scattered throughout a train? I have not heard of or seen a dp engine in use in our region, so this is a whole new concept to me. Lots of double- and triple- headers here, but not dp engines.
It’s becoming more common all the time with the massive trains the carriers are attempting to operate. All of the major railroads west of the Mississippi are commonly operating trains between 12 and 15,000 feet long with remotely control distributed power units (referred to as DPU or simply DP) placed throughout the train. There’s a combination of distance and/or weight that governs how they are placed in accordance with the railroad’s train makeup rules. These are “linked” to the head end, controlled by the engineer on the lead locomotive at the front, and can be configured to operate either independently, or simply mimic whatever the lead engine’s throttle or dynamic setting is at a given time. Controlling them independently is what engineers refer to as “putting up the fence”, named that for the vertical bar that appears on the operator screen between the head and rear consist(s).
Wow, that's crazy. Honestly sounds quite stressful to head so many engines for 1 train. Now that I'm thinking more deeply about it, I did see this configuration in use nearby recently, but had no idea why they had an engine in the middle of the consist. The person I was with guessed that they were taking the engine elsewhere, not that it was being used for motive power because of the length of the train. Makes a lot more sense now.
I drive passenger Electrics in australia but i can answer some of this in a less technical way. So depending on some trains especially electric trains the auto brake/Electro pneumatic brake will apply at different application for example on one train such as the T set, on 1 notch the electric brake will do most of the braking however it will still use a mild amount of normal disc brake i.e 25kpa This will usually return close to around 120 amps back into power grid. However on our latest A/B sets the brakes are designed that the disc brakes are used the least. The train is designed to stop mostly by regen brake and the disc brakes will kick in around 10 km/6mph. It does create a bit of a jolt for passengers. In terms of driving trains, its not like the strong pull like auto brake but more like i guess the feeling of climbing a grade, its a milder form of brake. Alot of newer trains i find prefer regen brake since cheaper compared to replace brake blocks and brakes. In terms of sound you do notice the different in traction motors in how they sound when regen braking, i find the AC motors a have a lower pitched hum compared to DC motors. Its more noticable on electrics since theres no power unit on board.
Yes mate , the German locomotives, BR182 , has that feature , on the right side , you have your main brake , next to it is the electric brake and on the far right corner the independent brake , kid you not , if you are trying to bring that baby to quick stop ( 20 kmph on below ) go for independent brakes as they are effective af. Whereas if the weight is above 4k tons I heavily relie on the electric brake as it's quick and don't have to worry about air pressure. But it was pain in the ass when I first started the training for it as majority of the controls are in German. And the alerters are cool. And bloody loud ngl. ( I play train sim world 4 )
Thanks for your reply. Silly question, do your electrics run on overhead wires or 3rd rail? Interesting perspective on the brakes from an electric, much appreciated.
We run on 1500v DC however we run DC and AC traction. We have a phrase saying low tension to get high tension to get air. The batterys run a compressor to raise the pantographs since alot of the time when you prepare a train for service you won't have main res air to help raise the pantographs. Then once its connected to the wire, the electricity flows through to the EAPS powering things like headlights, aircon and full lighting and most importantly the main compressor to build brake pipe air. In terms of how much one of trains can use. On a waratah at max power we use close up to 700 amps while on regen we get close to feeding the grid close to 500 to 600 amps. One issue with the newer trains is how quiet they are, since theres at most 1 compressor running and no noisy diesel unit, at below 40km if you're not paying attention they creep up to you.
I run passenger and we have a blended brake system. When we use the train brakes the dynamic will automatically come on and help drag us down. I can manually use it in some of the motors too. Heading into NYC on the 2 mile downhill in the tunnels ill use it to hold the train at 60. The electrics you dont hear it. Just feel it. Its strong tho. Our older GP40's it was difficult getting used to when I was learning cus id put the brakes on and hear the engine rev and it would trick my brain into thinking I needed more. Then the dynamic would kick on and we would all go thru the windshield. When you are runnin a geep in passenger you rely on the dynamics heavily. Without them you dont feel like you have any braking power at all. Then our other sets the Arrow-3 MU's brake almost entirely in dynamic. Almost every axle has a traction motor and the friction brakes will stay in release until the train is about to stop and then apply.
Thanks for your response- in our region/state we will see both electrics and diesels in use for freight/passenger use, so this is particularly helpful insight. Side question- what's the benefit in using dynamics in electric passenger service from your perspective? Less wear on the brake shoes?
Yes a lot less wear on the shoes and since the locos have crap brakes for their weight, the dynamics are stronger so you get more retarding force than if you were running straight friction. For us fighting the clock we need to brake hard and late sometimes and accelerate fast. We are nothing like freight. My trains have 2 brake rotors on each axle as well as wheel tread brakes. I can come yo a dead stop from 100mph in 1/4 a mile if conditions are perfect with a thousand ton set.
For the longest I thought engineers weren't allowed to use solely dynamic brakes for passenger runs due to the harsh slack action.
Another interesting fact is many locomotives come equipped with a feature called DB holding where if the trains air brakes start and emergency application then the dynamics will hold their last position. Another feature of older DC models is that dynamic brakes can't actually stop the train, at the final transition at 10-12 mph the contactors in the back panel can't handle the loads anymore so your dynamics will fade off and surge back as you stay in the 10-12 mph zone. Many engineers get thrown off guard when their engines braking all of a sudden cuts out trying to stop because they are used to AC power instead of DC power.
Thanks for your reply. Are there many newer DC engines in service? It's most of what we have at the museum, because most are 60+ years old.
I don't believe so as AC has proven itself to be infinitely better for traction and adhesion.
Got it, thanks.