If there is a caboose in your train - as to the prototype...
Pushing a metal caboose is much better for your health than pushing a wooden caboose.
Conemaugh Road & Traction circa 1956
jacon12 wrote:Here in central Georgia, where the land is fairly flat I don't think I've ever seen a helper pusher. Many double and triple headers of course. I would imagine that as you get more up into the Appalachian Mountains it may be common.Thanks for the information.Jarrell
Back in the 70's a couple long coal trains went through my neighborhood every day to service a power plant. They ALWAYS had helpers in the middle even though the line was pretty flat.Trains and locomotives did a show this mourning on the UP Cascade division. They'd pick up pushers in the last town before the grade and drop them in the first town after the grade. (I assume to wait for a return trip train to help going the other way)
tgindy wrote:If there is a caboose in your train - as to the prototype...Pushing a metal caboose is much better for your health than pushing a wooden caboose.
Actually, it's the frame that's the important factor here: wooden frame goes behind the pusher, steel frame ahead of- or behind, depending on each road's particular practice. There were many wooden cabooses with steel underframes. I run steel-frame cabooses, but generally place them behind the pusher, as it adds an extra operational dimension.
A pusher waits, with its caboose, for another train to clear...
...then backs to the waiting coal drag...
Wayne
markpierce wrote:Chuck said: " If either the road engine or the pusher stalls abruptly, the loco that's still running will simply spin its non-traction-tired drivers. That's the whole point of a train that neither locomotive can move alone. "Well, how did I as a guest operator once turn over almost an entire train twice in one day when the pusher stalled and the lead locomotive pulled the cars over to the inside of the curve? Mark
Chuck said: " If either the road engine or the pusher stalls abruptly, the loco that's still running will simply spin its non-traction-tired drivers. That's the whole point of a train that neither locomotive can move alone. "
Well, how did I as a guest operator once turn over almost an entire train twice in one day when the pusher stalled and the lead locomotive pulled the cars over to the inside of the curve?
Mark
There was evidently too much power on the head end. When your helper stalls (or even if it gets throttled back), this kind of thing can happen.
My point was that if the lead units will simply spin their wheels with that train without a helper, than adding a helper at the rear won't be any more of an 'anchor' for the train than just the train itself. But if the lead units can string line an unassisted train then running helpers becomes much more dangerous.
I designed my curves, train lengths and MU head end power with this in mind. The result is I've not (knock on plywood) had this kind of a problem (yet).
The live loads will also represent an especially tough case since the loads will raise the center of gravity of thes cars making them much more susceptible to super elevation problems.
Regards,
Charlie Comstock
BCSJ wrote: markpierce wrote: Chuck said: " If either the road engine or the pusher stalls abruptly, the loco that's still running will simply spin its non-traction-tired drivers. That's the whole point of a train that neither locomotive can move alone. "Well, how did I as a guest operator once turn over almost an entire train twice in one day when the pusher stalled and the lead locomotive pulled the cars over to the inside of the curve? MarkThere was evidently too much power on the head end. When your helper stalls (or even if it gets throttled back), this kind of thing can happen. My point was that if the lead units will simply spin their wheels with that train without a helper, than adding a helper at the rear won't be any more of an 'anchor' for the train than just the train itself. But if the lead units can string line an unassisted train then running helpers becomes much more dangerous.I designed my curves, train lengths and MU head end power with this in mind. The result is I've not (knock on plywood) had this kind of a problem (yet).The live loads will also represent an especially tough case since the loads will raise the center of gravity of thes cars making them much more susceptible to super elevation problems.Regards,Charlie Comstock
markpierce wrote: Chuck said: " If either the road engine or the pusher stalls abruptly, the loco that's still running will simply spin its non-traction-tired drivers. That's the whole point of a train that neither locomotive can move alone. "Well, how did I as a guest operator once turn over almost an entire train twice in one day when the pusher stalled and the lead locomotive pulled the cars over to the inside of the curve? Mark
Again, the theoretical. Helpers are added BEFORE the steep grade begins. Thus, the beginning grade is minimal and the power of the lead locomotive will be GREATER than that needed to pull the train at or near its starting point. I remain of the opinion that safe pusher-helper operation needs reliable and responsive equipment and control systems, as well as skilled operators. (I'm a quick student, and would welcome any open invitation to engineer a helper.)
Steam trains used multIple crews and engines for operation. Early diesels used Radio Control. Today they have MU 'connections and R.F.
Model electric train simulation is tricky to push a string of 'empties' since everything is designed for 'pulling'. A 'dummy' engine being 'pulled' SIMULATES the prototype with far less problems.
If you are needing more power, do whar Santa Fe did... add a string of matched ABBA units. Yes, they and their crew sat on a siding until needed.
Even with matched engines, I'd put the fastest one on the point. (We play with TOY trains).
I've run long trains (over 60 cars) on my layout with a pusher on the rear end. Because of the shape and size of the room, and my trackplan, there are many curves (34" minimum on the mainline) and many grades (2.8% maximum), both up and down. With careful handling and attention to proper speeds, such trains can be run safely, even on my DC-powered layout. It's quite interesting to watch the point of neutral slack move throughout the length of the train as different parts of the train move uphill and downhill at the same time, all the while coiled around several curves in various directions.
It's important that locos, rolling stock, and track be in good condition and up to standards, but there's no reason why anyone shouldn't be able to duplicate this feat, with some care.
Jarrell...I have, just south of Atlanta. A 108 (give or take) car coal drag, and 3 or 4 locos pulling, 2 pushing.
Rotor
Jake: How often does the train go by? Elwood: So often you won't even notice ...
Andy made a video about this a few years back. Helpers are becoming rare in the real world RCL and DPUs have replaced crews. There are some places where helpers and still needed first is the Blue Mountains in Oregon on the OSL Railroad UP who manages the line adds them at LaGrande and takes them off at Hinkle. Soldier Summit on the Rio Grande also uses them they go on at the appropriately named town of Helper and they are taken off in Provo. Also you see them in the Alleghenies on CSX railroads Sandpatch Grade also known as Blue Ridge and on NS' Horseshoe Curve. If you need to lug a heavy train over a mountain call a helper.
Something that hasn't been brought up yet (and is only of technical interest in modeling practice, I think) is that PRR, and perhaps other roads, made a clear distinction between two kinds of assist. One kind is when trains of a particular weight are given assistance to 'just' get them over a particular obstacle, probably at what becomes very low speed at the point of maximum resistance. The other kind is when speed is important, and the extra power allows negotiating the obstacle at higher peak speed and hence in shorter time... this of course being important for many passenger trains and for expedited fast freight.
This is where that odd-sounding term 'snapper' likely comes from; it's not just a quaint regionalism. You wouldn't put a pusher on the rear of a passenger train, and of course you wouldn't cut it into the middle of the consist; I suspect that even with long consists you're not concerned with pullaparts of various sorts. So it makes sense to put the snapper on the front, effectively turning the power on the point into the equivalent of a bigger locomotive.
The situation gets a bit blurrier when ATSF and UP used steam locomotives, some of remarkably low top speed, to assist streamlined diesel trains up some of the severe grades in the West. While this had the effect of increasing speed somewhat over what the diesels themselves could have accomplished, I get the distinct impression that where a 2-10-2 is the power concerned the ability to get up the grade is more important than how fast the feat is accomplished. So that would be a 'helper' rather than a 'snapper' in context.
I am not sure whether older pusher operations understood the concept of the 'node' as in modern DPU operations: that with power both pushing and pulling there will be a point within the train where coupler force (and hence draft-gear action) is effectively zero, and of course forces 'fore and aft' of that point will be proportionally reduced. Without the model equivalent of dynamometer car instrumentation measuring coupler forces, I can't say to what extent electrically powered locomotives would mirror what independent diesel-electrics, even coordinated by DPU commands, would produce as in-train forces.
Overmod...with power both pushing and pulling there will be a point within the train where coupler force (and hence draft-gear action) is effectively zero, and of course forces 'fore and aft' of that point will be proportionally reduced....
That's to what I was referring in my previous post. I hadn't even considered that scenario until I actually saw it occurring.
Overmod The situation gets a bit blurrier when ATSF and UP used steam locomotives, some of remarkably low top speed, to assist streamlined diesel trains up some of the severe grades in the West. While this had the effect of increasing speed somewhat over what the diesels themselves could have accomplished, I get the distinct impression that where a 2-10-2 is the power concerned the ability to get up the grade is more important than how fast the feat is accomplished.
The situation gets a bit blurrier when ATSF and UP used steam locomotives, some of remarkably low top speed, to assist streamlined diesel trains up some of the severe grades in the West. While this had the effect of increasing speed somewhat over what the diesels themselves could have accomplished, I get the distinct impression that where a 2-10-2 is the power concerned the ability to get up the grade is more important than how fast the feat is accomplished.
The grade over Raton Pass, for example, was compounded with very tight curves so increased speed wouldn't have been needed, or desired.
Ray
On Cajon pass all east bound Santa Fe trains have several helpers at the head end. But when they reach the ruling grade, which is the steepest part of the pass, the train stops and a couple of pushers which are waiting on a siding are added to the end of the train. They push the train up to the summit then they return by themselves back to the siding so they can push the next train. They are constantly busy because this is a very busy mainline. There is only one set of pushers but they only push just a couple of miles.
OvermodI am not sure whether older pusher operations understood the concept of the 'node' as in modern DPU operations: that with power both pushing and pulling there will be a point within the train where coupler force (and hence draft-gear action) is effectively zero, and of course forces 'fore and aft' of that point will be proportionally reduced.
The Rio Grande did. Helper ops using swing helpers over Tennessee Pass are often cited for requiring exactly this sort of play between train weight and the distributed power. Videos show this was the case even in the days of steam, as articulated helpers were distributed in this manner. Diesels simply changed the form of the power, not its distrbtion. The peak of this practice is generally considered when done with the Tunnel Motors although I also saw the newer SP AC power working over it before it was...gone, except for the rails.
Mike Lehman
Urbana, IL