Is it my imagination or is my train moving up my terrible 4% incline better (more smoothly) with the helper loco in the middle (swing) position than at the front with the lead loco?
I have always used two locos at the head of the train in a consist to move long trains up this grade, but today, for a change tried the second loco in the swing position. The entire train made the grade without the visible slowing when the locos are both at the front. It also came down the other side in better control than a headlong rush that needs quick throttling back when the locos are both at the front.
I’m happy if there is less wear and tear doing this…although part of the fun of th"big hill" is to test out the locos.
The position of the swing helper is due more to coupler tolerances than any other factor, because putting all the power on the head end could cause too much strain on the couplers and result in a broken knuckle.
If the engines aren’t perfectly speed matched, when you run them coupled together, the faster one is using part of it’s energy trying to pull (or push) the slower one along with the train. When they’re separated, it could be that the speed difference is offset by the cars each engine is pulling. For example if the faster engine is the swing engine, it may be it’s pulling the half a train behind it plus pushing the first few cars ahead of it, slowing it down just enough that the lead engine and the cars right behind it are now running at the same speed as the faster one.
My concern with using either mid train helpers or pushers is that if the helper is pushing harder than the lead engine is pulling, will that cause the train to buckle? I don’t know if that is a legitimate concern or not. For that reason I have always used my helpers as doubleheaders. It’s also easier to get the helpers switched into and out of the consist although for some, the added switching might be a plus.
If the road engine can pull the entire train, it doesn’t need help.
If the helper can push the entire train, plus the road engines, you have the locos assigned to the wrong ends of the train. The helper should be the (unassisted) road engine.
Optimum is that neither loco can handle the entire train unassisted. Somewhere between the road engine’s tender and the helper’s pilot beam there will be a car which is being both pulled and pushed. Its location can be determined by noting where couplers go from being pulled apart to being pushed together. This applies whether the helper is in the swing position, the pusher position or both.
I personally assign pushers (as did my prototype) to trains that need them. The pusher is always a six-coupled tank engine that couldn’t handle even half the cars in the longer freights by itself.
On the really hard climb, there might be a pair of six-coupled teakettles on the point and another pushing a train that could fit, comfortably, in a siding 42 inches long.
Chuck (Modeling Central Japan in September, 1964 - with small steam and steep grades)
It should be better since the complete train is not hanging on the coupler of the lead engines. Having a swing engine in the train takes a certain amount of the stain off of the lead locomtives and each car up near the front of the train. I think this should show up more on upgrade curves than on a straight line track since the first portion of the train also has less friction on curves.
A pusher on the rear of the train is more common than one in the middle and is easy to cut off. By pushing “harder” you probably really mean (in a model sense) running faster. In DCC you can speed match your engines so they run at the same speed so that shouldn’t be a problem. In DC if your helper is pushing on the rear and is going faster than the lead engine it could cause a derailment, that could also happen the other way around with the slower engine on the rear causing the cars to stringline.
Properly weighted freight cars could help reduce problems of course, light cars are more likely to have issues.
My club has a long 40 foot grade of around 3 %. There is no sight better than my BLI J1 and M1b on the front with my 2 PCM I1sa on the rear pushing 40 hoppers followed by the cabin. Just the sound alone is great. At the top I cut the rear pushers off and couple the cabin to the rear with the M1b. Then the 3 helpers drift down grade and wait for the next train while the J1 handles the down grade on the other side.
About three years ago I had 5 Alco RS series lashed up on the front of a 45 car mixed freight. The front coupler came out of the first car ( Damn Athearn coupler clip). Right at the crest of the hill. The whole train went backwards like a rocket the whole way down. I am still missing a boxcar somewhere in the layout and the guys in the cabin quit on me. From then on it has been pushers on the rear.
My 4% Mascoma Lake Grade in Enfield and Mascoma, NH, has a tight (22" radius) curve at the summit. Even with properly matched locomotives at the front and rear of long trains, the helper needs to shove harder than the lead locomotive(s) as the lead locomotives crest the summit and head downgrade as the helpers are still slugging uphill. The lead locomotives and freightcars are helped by gravity, while the helper is shoving cars up the grade.
The railroad does not use DPU or unmanned helpers - every set of locomotives must be manned. There’s a narrow window of speed where helpers won’t go too slow and stringline the cars at the summit, and where they won’t go too fast and send cars off the outside of the curve. I have placed trees on the slope down from the tracks that have saved more than one train from sending cars onto the floor!
I have an immediate 2.25% eastbound grade out of my main yard, and unless I’m using one of my big articulateds to man the train, I’ll usually couple one or two helpers ahead of the caboose if the train is over 20 cars.
Now I’m DC, so this can be a tricky proposition, but I’ve got about 5 non-articulated steamers (3 4-8-2’s and 2 2-8-2’s) that are geared extremely close. What I usually do is put one of the 4-8-2’s at the head and couple on either another 4-8-2 or my 2 2-8-2’s right ahead of the caboose as pushers. Generally, I can run the train as is over the entire layout without problems. But as I said, I have to be careful choosing which power to use where on the train. However, I find that this works much smoother for me than simply doubleheading locos. It also looks a lot more prototypical for the railroad that I model.
Besides, it’s fun and keeps me and my controller on my toes all of the time! [:P]
Thanks for all the info on your experiences, fellows.
I have been trying out more of my locos in this fashion. This is DCC and all are closely speed matched with at least one other loco for use on the big hill. The first pair I spoke of were Spectrum Dash 8s that I had out to pull around the rail cleaning car.
Soon I will try the steam locos (mine is a date-flexible railroad) with the helper at the rear or middle because this really does seem to work better than both pulling at the head end. My cars are all at the proper weight so that does help.
In reality I have spend years of watching BC Rail run their trains with three locos on the head end and two more in swing positions dividing the train into thirds. I can’t recall them ever running a pusher on the back.
Then again, this is a very tricky section of the line from North Vancouver to Lillooet and because the new owner CN proved they didn’t know how to run trains on it and were regulated to shorter trains than BCR, no more examples of helpers go by my house…only two locos on the head end.
I’ve read about a less common practice of doubling the hill where instead of using a helper, the road engine will take half the train to the summit, then back down and bring the second half up. I think I might have read this in John Armstrong’s book but I can’t find my copy right now so I’m not positive about that. As a variation of that, would it make any sense for the road engine to take half the train up the hill and the helper to bring the other half? Has any prototype used such a practice?
as for doubling the hill, most prototypes did it only in an emergency situation as it tied up the main line for a considerable period of time. on light traffic lines or coal branches, it was more common. the C&IM doubled or even tripled the the northbound grade at Petersburg Ill as a matter of course in regular operations well into the 6 axle diesel era. of course, they didn’t run too many trains either and their primary business was hauling coal.
on my layout there is a double track helix with a the outer diameter being 30 inches. When I would like to run 30 or more car freight trains there has to be a helper on the rear. This helper is a Kato SD40-2 from the last run. These locomotives are light enough not to cause any derailments due to the fact that they do not push hard enough but at the same time make enough of a difference to help the train move over the hill. It is great fun doing this and also cuts down on the coupler strain. Mind you if this train proceeds down the helix then the helper engine acts as a brake as well.
Does it make a difference in how much energy is required to move the train up the helix, no, but it reduces the in train stress points.
