If I bring my switcher out to help the long train up the grade, how do I know how much throttle to give it? How do the prototypes do it? Is there a slip indicator?
I am not sure of a actual standard practice, but I would imagine that a helper located on the rear could not push with a super great deal of force. If cars were empty, or very light to begin with, it would probably cause a train to buckle, or cause damage to the cars. I think I remember a rule of 6 or 8 powered helper axles behind a caboose, if that helps. And as to wheelslip, most locomotives that I am aware of have a wheelslip indicator of some type.
Hope I helped a bit,
Nagrom
If you do it with your model trains, you will probably be picking cars up from all over the right of way. The control system used by the big guys ain’t there on the little guys.
Bob
I use pushers on my long coal drags mostly for the hills we have that are too steep and especially on the helix. This is really not as hard as it seems, but you do have to be attentive.
All you have to do is give enough throtle to eliviate the weight on the head units once they start to slip (or at least I would start to get the hang of it that way). You will have plenty of slack to push up on before you compress the train and derail it.
I do run pushers in the same consist sometimes BUT that can cause a closeline affect around curves or IN EITHER CASE if the pusher stalls!
So, be careful around curves or you can pull an entire train down off the tracks!
Hope I wasn’t overly dramatic.
DCC makes it easier particularly if thge engines are speed matched but it is a dangerous situation in real life and can be on a model railroad. If I were going to do it I would make sure there was enough power on the head end to do the job and basically just have the helper go along for the ride doing minimal work if any. Allan Mccleland used Astrac to do it on the V&O so it should be fairly easy to do with DCC. Many real railroads did use the yard engine to get a train started out of town it couldn’t do otherwise. The PRR T-1 on several occasions would get hung up at station turnouts and require a help to stop spinning its drivers and spilling coffee. Once under way it could do 100mph however.
Very carefully?
I have never done it, but from what I’ve read the trick is to watch the couplers to see which cars are getting pushed and which pulled. The pulling engineer ‘drives’ normally, though carefully (don’t change anything fast, tell the helper before you do anything). The helper adjusts speed so that he is pushing about a third of the train. The boundary betweem pushing and pulling will be moving as terrain, curves, etc. change.
Actually, for a straight pusher (as opposed to a slave unit pusher) the control system is pretty much the same for a model as it is for the prototype: just keep pushin’ until the train is moving at the speed you want it to move. It helps if the loco that’s pushing is capable of running at the same speeds at similar throttle settings as the head-end power. If one the locos at either end of the train requires considerably more power before it starts moving, though, it will cause more problems than locos that run at dissimilar speeds. I often run pushers on coal trains, and with “live” loads, too, and have had zero problems with either derailments or stringlining. If you’re using DCC, I would guess that all of the locos should be programmed to start and run at the same speed, although in DC, I don’t worry about a little wheelslip occasionally. I usually run steam, but I’ve also had success mixing steam and diesel.
Wayne
While Jeff is obviously refering to DCC controlled locomotives, the slack run-in/run-out on a DC powered train acts similarily. With three similar locos on a train, two pulling and one pushing, the couplers of the front 2/3s of the train will be in extension, and those of the rear 1/3 in compression. the “neutral” point will move forward or rearward as the grade varies. I have run fairly long trains where different parts of the train are going uphill and downhill at the same time, and sometimes this occurs in multiple locations at the same time. Throwing in some curves increases the care required to move the train, but it should be do-able. It can also be a lot of fun. While I don’t run DCC, I’ve long thought that a pusher controlled by a separate operator would be one of the best features available. It would also be useful for doubleheaded steam, where each loco would have its own “engineer”. [;)] It’s just a question of who you want to run the train. [swg]
Wayne
In model railroading any train longer than one car is a long train when you are trying to shove and a time-proven recipe for disaster. If you need additional power to get your train over the hill try hooking an 0-5-0 switcher on the head end; that’ll do it every time!!!
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Have independent control (e.g. DCC) to operate the rear-end helper (pusher) separately from the head-end power. Have separate engineers for the head-end and pusher power (two “operators”).
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Start the pusher first. If the head-end moves faster than the pusher, you’ll turn over the train if you are on a curve. But don’t push too hard or cars could be derailed. (It is much easier to start/end the train on straight track than on curved track.
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Some cars in the train should be “in compression” at all time. and somewhere along the train there should be “coupler slack” (the point of equilibrium). Otherwise the problems in 2 will arise.
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If the head-end power is slipping its drivers, increase the throttle of the pusher. If all locomotives are slipping, get more locomotives or break the train into two parts. Ideally, the pusher should work no harder than preventing driver slippage of the head-end locomotives: cars behave better being pulled rather than pushed. Thus, you will have fewer problems if head-end power is greater than the pusher(s).
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At all times, be gentle on the throttles and closely observe the train, and have excellent track work. The situation can be intense.
Mark
To clear up what I meant in my previous thread, I usually have a different throttle for my pushers, I just borrow someone elses at the club. We usually have at least one guy who isn’t running.
I suppose it can be called “cheating”, but I’ve never run trains so long they NEEDED a pusher. That being said, standard practice on the TC was to couple a dummy or two into or onto the train to give the appearance of helpers. Things always seemed to work better that way…
But where is the challenge (fun) in that! (From one who has turned over more than one train using helpers. Advice: practice without a train with spillable loads.)
Mark
The most basic part of operating a pusher is that no locomotive should be trying to move another locomotive, ever. The easiest way to assure that this is the case is to assign:
- A road loco that can’t pull the grade unassisted (will start to slip before the entire train has transitioned onto the grade.)
- A pusher that can’t push the entire train up the grade unassisted.
- A pusher that operates at the same speed, or a little faster, with the same load as the road loco.
That way the train is never under tension and never under compression severe enough to pop cars off the outside of a curve. If the lead engine tries to take more than its share of the load it will slow down or, in worst case, slip. If the lead engine stalls the pusher will start to slip while there is still slack available in the couplers/draft gear of the leading cars. (Note that traction tires will have an unwanted effect on this calculation)
By the same line of reasoning, when doubleheading locos the faster should be the second unit, not the first. That way the faster loco will load up and slow, and the lead loco will then try to pull it to a higher speed. If the faster loco is in front, it will end up pulling the slower loco as well as the train.
Chuck (modeling Central Japan in September, 1964 - with a pusher district)
As a model railroader, I don’t like dealing with “absolutes” as R.T. Poteet has suggested in regard to using helper locomotives.
When I operate on one of my friend’s layout, where we quite often run 40-50 car long trains and use helper locomotives to push them up some of the 2.5 to 3% grades. Some of the cars have chunks of granite block, which is extremely heavy. These trains require helper service, and without it we’d never get it up some of the hills.
Yes, when we aren’t paying attention or screw up the order of starting/stopping or speeding up and breaking, or we do opposite things, yes, we have broken a coupler or two and derailed a train, but it’s never been catastrophic failure sending things going crashing to the floor.
With DCC control and careful adjustment of CV’s to match locomotives, you won’t have very many problems with an operator who pays attention.
I have had a set of engines on one throttle of the DT400 and the pusher on the other throttle running independantly. It requires total focus and attention to the entire train.
The lead engines set the pace and are left alone “Power wise” Most of the adjustments of power application goes to the helper.
I prefer to run sets in front but once in a while you need something shoving on the back.
If Im handed a throttle, told to use this engine to help THAT train over the hill, then my focus will be on the helper engine and the first few couplers of the last several cars (Caboose goes behind helper) on that train. If I see slack run in and the lead engine running normally I hold the power where it is.
It is a dynamic and ever changing situation nothing is constant in helper service. There are limitations. The heavy 2-10-2 shoves best below 30 mph. The PRR J1 giving the hand to the Duplex T1 will pretty much move any train while the ABBA BLI F units will find and break any plastic couplers on that train; mandating kadee couplers required anywhere on the railroad.
BTW, I loved the T1 slipping on switches and spilling coffee picture very much.
Ok, at the model RR club I belong to has some grade near 4.0. I remember I had my Atlas HO PRR F-M H16-44 handling a coal drag by itself. When I came to the point of the mountains I had a pair of GP35’s come out and help (I know they should be doing the drag themselves but I was breaking in the H16-44) what I did was when the wheels started to slip I shut down then H16-44 and waited for the helpers to get there when what I did was couple the helpers to the train with the kadee couplers delayed and I watched the slack in the cars and the speed of the wheels ont he engines also, if your lead unit is spinning add more helper power, and if the helpers are going to faster they will jerk trying to push the lead unit just find that hapy medium. as the middle of the drag started the down grade Thee cars carried the train away from the helpers and I shut them down and returned them to the start of the grade, normally the weight of your units leading will keep the train running away when you do it this way, but if you think it might run away dont delay the helpers couplers to the train and use the helpers to add drag. Mike
Mark, I’ve found that using “live” loads gets me to pay close attention to what I’m doing when I run trains in this manner. [swg]
[quote user=“tomikawaTT”]
The most basic part of operating a pusher is that no locomotive should be trying to move another locomotive, ever. The easiest way to assure that this is the case is to assign:
- A road loco that can’t pull the grade unassisted (will start to slip before the entire train has transitioned onto the grade.)
- A pusher that can’t push the entire train up the grade unassisted.
- A pusher that operates at the same speed, or a little faster, with the same load as the road loco.
That way the train is never under tension and never under compression severe enough to pop cars off the outside of a curve. If the lead engine tries to take more than its share of the load it will slow down or, in worst case, slip. If the lead engine stalls the pusher will start to slip while there is still slack available in the couplers/draft gear of the leading cars. (Note that traction tires will have an unwanted effect on this calculation)
By the same line of reasoning, when doubleheading locos the faster should be the second unit, not the first. That way the faster loco will load up and slow, and the lead loco will then try to pull it to a higher speed. If the faste
I think you missed thobvious, it;s called MUing. You prgram a DCC controller for both engines to accelerate at the same rate. Therefure, your not so taught that you wreck, and you don;t start throwing cars off the side. It does work better with two engines together though.
Also, think anbout doing this with an engine in the middle. May take a moment when you get up to the top to get her out, but it beats the alternatives.
For either mid-train or en-of-train helpers I’m not convinced that MUing is the way to go. (I wish I had enough layout done to try this stuff out!) Very small differences in speedsm even just due to the difference in the load on each loco could really change how the train handles. I think an attentive operator is a better controller. (As has been pointed out, this could work with DC, as well, as long as the blocks are short enough to keep the helpers in a different block from the head end.).