How does the engineer of a freight train control the slack if the train stops on an upgrade? Downgrade? No grade (if there is such a thing)?
On a recent trip from El Paso to Tuscon on the Sunset Limited, a Texas Eagle passenger on the through sleeper told me that he did not like to ride in the last car because of the whipping effect created by the slack running in and out.
I am under the impression that Amtrak's Superliner cars, at least, have practically no slack action because of the lock tight couplers. Am I correct?
Rio Grande Valley, CFI,CFII
JPS1 How does the engineer of a freight train control the slack if the train stops on an upgrade? Downgrade? No grade (if there is such a thing)? On a recent trip from El Paso to Tuscon on the Sunset Limited, a Texas Eagle passenger on the through sleeper told me that he did not like to ride in the last car because of the whipping effect created by the slack running in and out. I am under the impression that Amtrak's Superliner cars, at least, have practically no slack action because of the lock tight couplers. Am I correct?
The only adverse side-to-side motion I recall comes from the rocking caused by track that needs surfacing (the worst ever in my memory came last year when the California Zephyr was detoured across Wyoming and we had to enter Denver over the Belt Line--which seriously needed surfacing. I did not remember such rocking the year before when we were detoured going west.
Johnny
I would suppose that if it's a longer train, there will still be a little slack - and if you're sensitive to it, you'll probably notice.
If we assume just a half inch of slack between cars, that's still ~5" for a 10 car train. Not much, but it could be enough...
The side-to-side thing might have some validity for the last car. The rest of the cars have at least one car on either side (end) that may dampen such motion. So there might be a little "whip" at the tail end of the end car.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
And to think, in the glory days of passenger rail, the Observation Car, on the rear of the train, was one of the featured cars on the train. From my times riding a multitude of passenger trains, I have never noticed any perceptible slack action. A little stretch braking steadies the slack; of course now a days stretch braking is viewed as a waste of fuel.
Never too old to have a happy childhood!
Deggesty Yes; tightlock couplers have very little, if any slack. Did he mean a side-to-side motion--which would not be caused by slack action?
Yes; tightlock couplers have very little, if any slack. Did he mean a side-to-side motion--which would not be caused by slack action?
He said that he could notice the slack running in and out in the back car. He also said that the back car sways from side to side more than the other cars.
I have ridden in the last car of the Pacific Surfliners from LAX to San Diego and back numerous times. Most of the Surfliners have six cars. I never noticed any slack or swaying, other than perhaps over a bit of rough track. But then I usually have my nose buried in a book, so I may not have been aware of it.
If there was slack action on a passenger train, I think I would have experienced it on a twenty eight car Canadian train in the Park car and there was none. However, I do notice something like slack action on the Metra commuter trains when the engineer transitions from power to braking and the cars do a small jerk.
BaltACD And to think, in the glory days of passenger rail, the Observation Car, on the rear of the train, was one of the featured cars on the train. From my times riding a multitude of passenger trains, I have never noticed any perceptible slack action. A little stretch braking steadies the slack; of course now a days stretch braking is viewed as a waste of fuel.
The mechanics of the 'tight-lok' coupling system is a definite plus that adds much to the ride in a passenger train, possibly a consideraton might also be made to the intra-car diaphragm system (?) which might put some seperation between the cars of the train, and cushion some of the 'slack' action ?
The biggest help for improving the 'ride' of the passengers, I think, isx the individual skill of the Engineer at the controls. Their knowledge of the track, terrain, and handling is critical for the comfort of the passengers; not to mention that their individual skill set is constantly on display.
Any passenger at any time can complain to the railroad management about a ride. A poor ride could generate a flurry of derogatory e-mails within a short time of the incident. Possibly, at the end of the trip, a compliment/comment (?) or two could also be sent to that same management about the trip.
I live adjacent to a secondary main line, wigth a rising grade from West to East. I can tell you the larger number of engineers do a remarkable job of train handling, they pass by with barely any notice...and then you have the occasonal happening ( Engineer in training(?) or maybe very tired(?) whose stop sounds like the whole train is being put on the ground, or every knuckle is being pulled apart)
Unfortunately, most of these happen during night, when everyone but the train crew istrying to sleep.
There is slack and then there is slack.
Free slack is the lost motion in the couplers, knuckles, etc.
Then there is the slack due to compression and expansion of the draft gear. The couplers are not rigidly pinned to the car underframe, they're connected by a big spring (okay, not really a spring, usually rubber pads...). There is a lot more slack action from draft gear motion than there is from free slack.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
I've handled a few Amtrak detour moves. Our crew change point going east is at a street crossing. The first time handling a detour move, I started the train real slow to allow the crossing signals and gates to activate. The Amtrak conductor radioed to me that I could just pull on them once we started moving. That I didn't have to worry about pulling the slack out of the train like you would with a freight train.
We made one stop that trip to change Amtrak engineers (both of whom rode back in the train) near another street crossing. Starting up I again had to go slow until the crossing was protected and again the Amtrak conductor said not to worry about any slack.
When detouring, we have a pilot engine (for cab signals) and use the freight setting for the automatic air brake. Even though we don't have graduated release or blended braking, they are still fun to run.
Jeff
Sorry, Covers information already posted.
Thank You.
This conversation reminds me of something that happened in the late 1980's or early 1990's.
The late Thomas Dressler, respected author, N&W engineer, and N&W historian, rode the Auto Train as a passenger and wrote a letter to Amtrak President W. Graham Claytor to express his thanks to the crew for a good trip. He specifically cited the engineers' excellent train handling in his letter. It's the only time I ever heard of a passenger saying anything like that. It's easy to take it all for granted; but if you're used to handling long Manifests and coal trains, as Mr. Dressler was, then you know.
Mr. Claytor made sure the employees saw copies of that letter.
Tom
NDGSlack was useful to aid a steam locomotive in starting, as the Engineer would back into the train bunch it in, and then start forward, using the independent and throttle to ease the into the load, the Slack adding the weight one car at a time, the moving cars helping to break loose the standing cars behind.
I've seen that done with Diesels, too, back in the day of "friction" bearings. The logic was the same, though - start just one car at a time instead of the entire train.
There has been a couple good articles over the years on how the crews run the Auto Train. They power brake it to keep the slack tight and from running out, mainly because of the size of the train and the autorack cars at the rear end. I have ridden it a few times and always had a great ride. Those are talented engineers
I appreciate the answers so far, but what I really want to know is how an engineer deals with the slack on a freight train that stops on an upgrade vs. a downgrade vs. a flat profile. Is there any difference?
If possible, my guess since I am not an engineer, when stopping on an upgrade, the engineer would want to run the slack in so that he or she could use it to help start the train? Is this correct?
Can the engineer apply the locomotive brakes independently of the car brakes? If the answer is yes, presumably then he or she could apply the locomotive brakes more robustly than the car brakes when stopping on an upgrade, thereby allowing the slack to run in? Is this correct?
There's a huge difference. If you are stopped on an uphill grade there are many factors. Train tonnage, curve radius, the gradient, how much horsepower you have, are there pusher engines, etc. If the train is starting uphill normally, then the engineer may release the train brakes, hold it with the independent brake and carefully put enough power into it to start gradually get the train moving without slipping. That could cause a separation in the train by a broken knuckle or worse a pulled drawbar. Either way you're going into emergency and now more problems to deal with. Like a trainmaster or roadforeman to say the least. If you had helper units, then you have the slack coming into you a little as you get going . Big difference. Downhill is a whole different animal. You might stop with a combination of dynamics and air. Starting up depending on the tonnage, the independent could hold you and a train release and slowly release the independent to start you going and back into your dynamic brakes blending it with your train brakes. Small releases are the key so you keep going and don't have to stop again on the hill or use up all your air so you only have an emergency application. Bottom line is this is someone that needs to know what they are doing, experience and a good teacher that gave them pointers. Plus a feel for each train you run, they are all a little different.
When stopping on an upgrade the slack would normally be stretched out. That's the way you want it. Taking slack to start the train is normally not needed with diesels. (I've only had to do it once because we stalled on the ruling grade when a trailing unit shut down. We were able to get it running and my engineer had me take a little slack to help start us.) Diesels can put out high tractive effort when starting, steam engines develope it at higher speeds. Hence, the need to start the train one car at a time.
With the slack in on an uphill grade, when you release the air brakes you could have the rear end start to roll back before it gets started. Depending on the type of train, that alone could snap a knuckle. Add into it the shock when the part of the train is moving forward meets the part rolling backwards and that could break the train in two.
Even starting a heavy train that is stretched out can be problematic. You need to use higher throttle positions, thus giving higher tractive effort. Should the locomotives momentarily slip it could allow just enough slack to run in and snap a knuckle when it starts to grab again.
Down grade, using dynamic braking, the slack will be bunched up. Using the automatic air brake for the stop won't stretch the slack out. When starting, just release the air and let gravity help you get moving. Use the engine brakes to keep them (engines) from rolling out to fast until you can go into dynamics or power if needed.
Making a stop on a level portion, it depends on the train. Some trains, those with a lot of cushioned or long travel draft gear, I would rather keep the slack stretched out. Others I'll use dynamics more approaching the stop, letting the slack bunch up. Just remember the condition of your train when you start again. At crew changes we usually let the outbound engineer know if the slack is bunched or stretched.
I've been talking about breaking a knuckle. That's really if you are lucky when things go wrong. If you aren't, you may have ripped out the entire coupler. If you are really not lucky, maybe a wrong ender.
jeffhergert I've been talking about breaking a knuckle. That's really if you are lucky when things go wrong. If you aren't, you may have ripped out the entire coupler. If you are really not lucky, maybe a wrong ender. Jeff
I was following that series of explanations fine until the term "wrong ender". That is a new one to me. Could you please elaborate on what that is?
Dakguy201 jeffhergert I've been talking about breaking a knuckle. That's really if you are lucky when things go wrong. If you aren't, you may have ripped out the entire coupler. If you are really not lucky, maybe a wrong ender. Jeff I was following that series of explanations fine until the term "wrong ender". That is a new one to me. Could you please elaborate on what that is?
When the 'wrong end' happens, the end of the train with th operating locomotives have no means of coupling to the car that has 'lost' the wrong end. On a Eastbound train if the East end of a car has it's coupling pulled out of the car - that is the wrong end. That car can now only be handled with engines on the West end of the train or cut of cars.
Only other potential band aid, is for the Car Dept to show up with chain(s) that can be affixed to the East end of the bad order so it can be handled to a set off location.
Jeff,
Thanks for your understandable explanation.
Jeff, I am sure that you are aware that I am a dinosaur who knows what the controls for a diesel engine used to look like--throttle, reverser, train brake, and engine brake (I was going to write independent or, even, straight air brake, but feared that that would confuse some who are new to the art of running an engine). With the changes in controls, I assume that you still have the engine brake and the ability to bail the engine brake off when it necessary to do so when using the train brake; I am wondering if this is done in the same manner as it was formerly. My only experience in running an engine consisted in running a light engine around a wye; I do not remember if I used the engine brake or train brake when I had to stop (the last time was about 42 or more years ago).
Yes, still have the Independent and Automatic brake valves. And we still have to bail off the Independent when making an Automatic brake application.
In the pre-alerter days some engineers would block the independant handle in the bail-off position, so they didn't have to depress it every time they set the automatic. If you tried that now it will trigger a penalty brake application after a few minutes.
Greetings from Alberta
-an Articulate Malcontent
NDG,
Thanks for your comprehensive explanation. I figured the task was more challenging than meets the eye of someone who has not been there; you have provided some great insights regarding how engineers deal with slack.
Hello everybody
a great thread and appreciate all the great responses. Very informative.
Frank
"If you need a helping hand, you'll find one at the end of your arm."
I had occasion to ride many passenger trains "back in the day" and, although I always watched out for it, I was never aware of appreciable slack action. The only adverse motion that ever impacted me was when riding in a duplex roomette or a bedroom with the bed across the car's width (rather than parallel to the length of the car). On those occasions, the train invariably stopped for some reason on a curve and left me standing on my head. The opposite, of course, was true with non-duplex roomettes and bedrooms arranged lengthwise; then the normal rocking motion was like being in a giant crib and put me to sleep.
Then there was the infamous Buffalo Switch on the NYC. Buffalo seemed to find some reason to rearrange every train passing through between 11 pm and 3 am. And they added insult to injury by switching with the enthusiasm usually reserved for handling box cars. Pittsburgh was much better in this regard. I normally slept through my Pullman being set out and the porter would have to wake me up so he could go off duty at 8 am.
ChuckAllen, TX
Also from the past, oprating a Boston and Maine freight once, with the engineer close by and instructing every more, but plenty of time watching him on B&M GP-7s 1567 and 1568, passenger North Station - Portsmouth, freight return to Sommerville Yard. I never saw taking up slack on the passenger. Not necessary. He did do it on the frreight, but gently. He would apply just enough throttle on starting to get the locomotive moving, and as slack stretched out kept the speed around 6 mph until he heard the conductor at the rear anounce "moving" or "on the roll" IF he had radios working, otherwise just judegement, and then he would notch out to run-8 to accelerate to track speed.
I supposed if I were stopped today on a downgrade, with a long heavy freight, I would gradually realease the train air, hold some engine brake, not enough to flatten wheels, and let the force of the bunched cars at the front force the locomotive into motion, but not release the engine brake completely until the Fred at the rear says the rear is in motion. Then gradually apply engine and train air to controll speed. Engine (dynammics) alone if suffiicnet. Any comments from the professionals?
When starting a train south out of one of our stations, it's usually enough to simply release the brakes. Since the train probably came in uphill, and stretched, you'll normally feel the cars run in, but not hard.
The operation of trains ALWAYS has to deal with the physical characteristics of the territory being operated upon - it is very rarely ever level.
Lots of great info and thanks to all who replied. I do remember being in B&O diner that was the last car returning from Wash DC, they had cut off the sleepers. And there was more of a sway and bounce, we could tell by how the waiters moved to work with the difference.
I was in last car on UP City of St. Louis when friends and I took a Pullman bedroom, and we did notice a little more sway, but it was not slack. Just not having anything behind us to anchor, a mild crack the whip. I was also in last car on Empire Builder sleeper and did notice more of a swaying motion in the Superliner cars that I'd ever noticed in a coach or the Pullman sleeper. It sits higher, that's why the train was on slow or stop orders when I rode SW Chief because there were tornado warnings out in KS and attendant said if winds gets over 60 mph, they have to go slow or even stop.
I did notice a gentle bouncing when I rode sleeper on CP Canadian because it was a lower berth which sat right above the wheels, not just my feet like UP or Amtrak. Sometimes it bounced pretty good and I hoped we'd stay on the track, because the flange is not very deep.
Mom had aunt who married a Frisco engineer and he had a rep for running a very smooth train. Gentle stops and starts, they always knew when he was on the head end.
Slack can be brutal from what some of you said and what I've heard. Have taken caboose rides with local railfan group on excursion railroads and see the signs warning about Slack. Of course, those trains go slow so not a real problem. I've shared about the UP City of St.L going 100 mph thru WY to make up time and the dining staff dropping dishes and falling into each other. That alerted Dad to the fact that something was unusual. I wouldn't want to have slack running in or out at that speed.
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