BigJim timz Can he release the brakes and start the train without it rolling backwards down the hill? Yes, I've done it I don't know how many times...with full tonnage...on a 1.75% grade! timz None of us has a good idea of what today's units can be relied on to haul up a given grade. On a long 1% grade, say -- with 6000 trailing tons in 50 cars, would an ES44 have a 90% chance of making the grade, or more, or less, on a dry day? So we don't know how tough a given tonnage rating is, so we don't know how much margin a unit has to restart on the grade. Yes, we do. Tonnage ratings for each type of locomotive are spelled out in the timetable!
timz Can he release the brakes and start the train without it rolling backwards down the hill?
Yes, I've done it I don't know how many times...with full tonnage...on a 1.75% grade!
timz None of us has a good idea of what today's units can be relied on to haul up a given grade. On a long 1% grade, say -- with 6000 trailing tons in 50 cars, would an ES44 have a 90% chance of making the grade, or more, or less, on a dry day? So we don't know how tough a given tonnage rating is, so we don't know how much margin a unit has to restart on the grade.
Yes, we do. Tonnage ratings for each type of locomotive are spelled out in the timetable!
CN took the tonnage ratings out of most subdivision timetables years ago. Probably so crews can't complain too hard or refuse a overtonnage train.
Starting a heavy train on a grade is indeed an art. Stopping with the train stretched is normally beneficial (so the slack won't roll out backwards, potentially hard enough to break a knuckle), but I've had to take slack (bunch it up) to start particularly underpowered trains a few times.
From observation, it seems that DC power will reliably make it up grades as long as the horsepower per ton (HPT) ratio is .1 to .2 greater than the grade. AC power HPT needs to be equal to the grade. As an example, the ruling westbound grade on CN's mainlines from Edmonton, AB to the Pacific coast is 0.4%. Trains with all DC power are often loaded down to 0.6 or 0.5 HPT, while trains with AC power are dispatched at about 0.4 HPT. These trains occasionally stall on certain hills in rain/snow or when the Dispatcher stops them in a bad place (as Balt noted), but most of the time they make it, climbing the grades at around 15 mph.
They tried running 170 car potash trains with only two ES44AC's for a little while, which is about 0.37 HPT. They stalled too frequently, and this operation went back to three units.
While I obviously never worked with cabooses, I've heard many stories from older co-workers who did.
Conductor: "I don't know what you did up there, but the coffee and dishes are all over the floor!"
Engineer: "Don't worry, I'll put them back!"
Greetings from Alberta
-an Articulate Malcontent
BigJim tree68 Starting from bunched, however, is one reason cabooses are gone. The last car in the train would suddenly go from zero to however fast the locomotive had gotten up to - often enough to knock crew members off their feet. What a crock of BS! Where do you guys come from???A good engineer would gently pull out the slack until the rear notified him that the cab was moving.
tree68 Starting from bunched, however, is one reason cabooses are gone. The last car in the train would suddenly go from zero to however fast the locomotive had gotten up to - often enough to knock crew members off their feet.
What a crock of BS! Where do you guys come from???A good engineer would gently pull out the slack until the rear notified him that the cab was moving.
Unless there was a Hatfield - McCoy feud between Conductor & Engineer. Rough ride guaranteed!
Never too old to have a happy childhood!
tree68Starting from bunched, however, is one reason cabooses are gone. The last car in the train would suddenly go from zero to however fast the locomotive had gotten up to - often enough to knock crew members off their feet.
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timzCan he release the brakes and start the train without it rolling backwards down the hill?
timzNone of us has a good idea of what today's units can be relied on to haul up a given grade. On a long 1% grade, say -- with 6000 trailing tons in 50 cars, would an ES44 have a 90% chance of making the grade, or more, or less, on a dry day? So we don't know how tough a given tonnage rating is, so we don't know how much margin a unit has to restart on the grade.
Lithonia OperatorMy basic question, I guess, was really about two things: - How close do the power-needs guidelines cut it regarding the ruling grade (particularly if, say, that one grade is an outlier in relation to the others)? - How much part does inertia/momentum play in the guidelines and in actual practice? Seems like you guys are saying "little or none." I had been wondering if the supposition was that (for example) 90% of the time, or more, the train would have a good head of (figurative) steam up when it arrived at the hill; and in the unlikely event the train had to stop on the grade, they could always double the hill. The idea being: don't use more power than necessary, so it can be used elsewhere. Are power guidelines adjusted in the winter, to account for slippery rails and snowdrifts? For you engineers: have you ever used the entire load of sand on one trip?
- How close do the power-needs guidelines cut it regarding the ruling grade (particularly if, say, that one grade is an outlier in relation to the others)?
- How much part does inertia/momentum play in the guidelines and in actual practice? Seems like you guys are saying "little or none."
I had been wondering if the supposition was that (for example) 90% of the time, or more, the train would have a good head of (figurative) steam up when it arrived at the hill; and in the unlikely event the train had to stop on the grade, they could always double the hill. The idea being: don't use more power than necessary, so it can be used elsewhere.
Are power guidelines adjusted in the winter, to account for slippery rails and snowdrifts?
For you engineers: have you ever used the entire load of sand on one trip?
On the pre-PSR CSX the Power Corordinators tried their level best to apply exact power to the tonnage rating of a train over the ruling grade of the ENTIRE TRIP - many of the territories the train operated over had tonnage rating much higher than the tonnage rating of the ruling grade. In the case of mountain grades where manned helpers were used, it was expected the maximimun number of powered helper axles would have the proper rating to get the train over the ruling grade. The PoCo's would take great delight in powering at 15,985 ton train with power rated for 16K tons. Tonnage rating was 'Gospel'. Some trains made the grade, a few didn't. Some trains with 17K tons and power rated for 16K tons also made the grade. There are a lot of conditions that enter into a train successfully climbing a grade - weather (hot, cold, wet, dry, snow, ice); exactly where the tonnage is in relation to the max grade segment, are the greasers functioning properly etc. etc. etc.
On the CSX line between New Castle, PA and Willard, the ruling grade is at Akron Jct. In the days I worked that territory, there was a Permanent 10 MPH slow order at the base of the grade which was slightly over 1% from the base in each direction. A ore train with max rated power would frequently stall - the ENTIRE weight of the train was on the grade, in it's entirety. A auto parts train with the same power and tonnage as the ore train would sail right along - the train never had its FULL tonnage on the grade at the same time account the length of the train.
When I worked CSX's Atlanta Division, from Tilford Yard in Atlanta there were three grades encounted to Manchester, GA. At the time I was working the territory, 90 cars was the normal coal train and the normal power was two GE Dash-8's. The coal train weight would be within a couple hundred tons of the tonnage rating for the locomotives assigned. In 'normal' dry weather trains would rarely stall, and the most frequent issue in the train's stalling was the the Train Dispatcher having lined the train past the next control point in advance of Manchester without out having them lined through Manchester - complying with the approach signal in advance of Manchester would result in a loss of momenturn on the grade to the Manchester control point.
At one point in time CSX limited ALL COAL TRAINS to a maximum of 40 MPH - fuel conservation was the 'reason' (excuse). This also cause serveral coal train stalls account of loss of kinetic energy developed in descending one grade to be used in climbing the next grade. The topography from Atlanta to the Southeast is a continuing series of rolling hills - and like most railroads in the South, the tracks are built on top of the lay of the land with little to no grade changes beyond the lay of the land. The Division prevailed upon Headquaters to conduct a test of train operation between Atlanta and Waycross - two trains, same level of power, same tonnage. One operated with maximum of 50 MPH that applied to all other freights and one operated with the 40 MPH coal train restriction. Result of the test was the 50 MPH train used 150 gallons LESS fuel than the 40 MPH train. The 40 MPH train was having to apply brakes descending grades and therefore had to pull harder and longer to climb the following ascending grade.
Current day locomotives have fuel tanks that permit approximately 1000 miles of operating at Notch 8 running conditiond - the sand boxes are sized for that length of trip.
My basic question, I guess, was really about two things:
Lithonia Operatorthe train is stopped on the ruling grade, with no slack. Can the engineer get the train going?
None of us has a good idea of what today's units can be relied on to haul up a given grade. On a long 1% grade, say -- with 6000 trailing tons in 50 cars, would an ES44 have a 90% chance of making the grade, or more, or less, on a dry day? So we don't know how tough a given tonnage rating is, so we don't know how much margin a unit has to restart on the grade.
As for how much it can start on the level -- first thing to find out is how much pull is needed to start the train rolling. So park the train on a carefully-measured 0.1% grade and release the brakes. Does it start rolling, just by gravity? If not, try 0.2%; I'm guessing that will be enough.
In other words boring homogeneous conveyor belt computer controlled ho-hum verses human on the spot ingenuity, the 'I think I can' workings effects of steam and man, a drama fit for the stage. Well worth watching and listening to.
One way the world has improved since the age of steam. In the 'bad old days' the engine could pull any train it could start, but (1) it could only start limited resistance 'at one time' without risking slip (or stall) and (2) it needed to get up to particular speed to start winding the reverse back to good cutoff without peaky torque issues, and to get reasonable horsepower at higher cyclic. That meant that an engineer might well be getting the head end to relatively high speed by the time the last few draft gears were coming out - and interestingly high rates of short-term acceleration would be observed... perhaps especially if the brother running the engine didn't care for snakes...
Nowadays with AC drive and roller bearings, the start can be made keeping constant speed once above a couple of mph until the whole train is stretched, then throttled up from there. While most hydraulic underframes work better in buff than in draft, there's still a longer travel and better accommodation of any transient run-ins that might produce 'shock' accelerations.
As to the noise of slack as it ran in, the most notable example that I remember came one night back in the mid-sixties, when I lived on the main line of the IC 55 miles south of Jackson, Mississippi. I heard a great bang out front, went out, and learned that a southbound freight had to get out of the way of the City of New Orleans--by backing over onto the wrong main. The engineer had started braking right after passing the crossover switches, which were ground throw switches (talk about knowing your territory--no switchstands). The conductor or rear brakeman told him when the rear had passed the switches by throwing a lit fusee up in the air; they had plenty of time to line the switches before the caboose reached them. I did not count the cars, but from previous countings, I would say that there were about 180 cars on the freight. The engineer stopped the freight short of the fouling point--and the City was right at the SB fouling point when the switches were lined for through operation, and was moving when I saw its engine; it obviously had crept up after passing the previous signal.
Johnny
From what I've heard over time, starting a train from bunched was a practice necessitated by the old friction bearings. The oil in the journals was the practial equivalent of roller or ball bearings.
A standing car would push the oil from between the axle and the bearing, leaving a metal on metal situation. Trying to start an entire train in that condition might require more "oomph" than the power could provide.
Starting the train from bunched meant starting only one car at a time, even if it was only a foot or less. The rolling car would quickly pick up the film of oil between the axle and the bearing surface and roll more easily.
With roller bearings, this phenomenon doesn't really exist. The only force to overcome is inertia. I would suppose that starting from bunched might make a little difference, but the need for it would be rare.
Starting from bunched, however, is one reason cabooses are gone. The last car in the train would suddenly go from zero to however fast the locomotive had gotten up to - often enough to knock crew members off their feet.
I recall a situation from my youth, seeing a train of coal hoppers apparently stalled on the grade through Milford, MI (Saginaw line). As I watched from a crossing mid-train, several attempts were made to get the train moving by bunching the train, then pulling out the slack. My most notable memory is the bang-bang-bang-bang-bang-bang-bang-bang-bang of the empty hoppers as the locomotives pushed and pulled on the train.
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...
Lithonia OperatorNow the train is stopped on the ruling grade, with no slack. Can the engineer get the train going? Or will they have to double the hill?
Let's take your average freight train, in this case one that has enough locomotive power to deal with the ruling grade on the line (according to guidelines), but not much more.
1) Let's say that on level ground, the engineer rolls forward slowly, taking up slack. Then, once all slack is stretched out, he stops without letting any slack occur. The train is fully stretched out. (This is hypothetical.) Could he now start the train moving, all at once?
If the answer to the above is Yes, let's say this train proceeds until it is on the ruling grade and suddenly the engineer needs to bighole it. (Let's say he sees people on the track, but stops before hitting them, then the people leave.) Now the train is stopped on the ruling grade, with no slack. Can the engineer get the train going? Or will they have to double the hill?
Still in training.
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