The thread on unit coal train lengths got me thinking a bit.
Assume you have 2 lead engines and 1 tail engine. What is the best way to position the engines in relation to each other as far as their on speeds.
To clarify, assign the engines with numbers 1,2 and 3. Assume that in a “race” on 3 parallel tracks that they finish #2 first, #1 second and #3 is last. My thinking is that if you place #2 in lead followed by #3 they would “cancel” each other out speed wise and with #2 on the tail it should maintain a pace as to not drag the cars off the inside of the curves nor shove them off the outside off the curves.
What happened to loco 1? [oops]
If you’re not using DCC, speed matching is out. In DC, the engines would still have to be fairly closley matched or you are asking for trouble. If you plan to have two units up front and a mid or rear helper, you wouldn’t want the fastest loco in front as it would always be pulling the second loco and there would be straining and jerking on the couplers. Placing the fastest loco second is better, as it will try to pull the whole train and thus be slowed down to the point the lead engine will start to contribute to the pull. The mid speed loco should be fine in the middle or rear of the train.
So, #3 up front, followed by #2 with #1 as a mid-train or rear pusher. This would also be more stable when operating the train in reverse.
If you are going to run all three locos up front, fastest in the rear.
If you run in DC then stick to Kato and Atlas engines. They are very consistent in their speed ranges and run well. I own about 15 Kato engines and they are all very well matched in their speed to the point that they can inserted anywhere in the train and no derailments. Same goes for all of the newer Atlas engines. Also if I double head a train it is not unusual to see Atlas and Kato engines mixed in together. No such luck though with Athearn and P2K engines. They all run at a different speed.
Otherwise I would put the fastest engine in the lead, the second behind the lead engine and not use a pusher at all unless the two lead engines could not pull the train. If they could not pull the train then I would put the third and slowest engine in position three, otherwise you are only asking for trouble.
The best way to assure that a pusher will not cause problems is very simple. Assign a pusher that CANNOT push the entire train (less lead locos) up the grade. Assign head end power that CANNOT pull the entire train up the grade.
When under way, somewhere between the head end and the front coupler of the pusher (or in-train helper) there will be one car that is being both pulled from ahead and pushed from behind. As long as that balance car is not a locomotive, you shouldn’t experience any problems.
Chuck (modeling Central Japan in September, 1964 - with pushers)
Why don’t you try different combinations and see what works best for you? I run Bachmann and Athearn steam together and/or either with Atlas diesels and/or remotored Athearn diesels. If the speeds are fairly close, it doesn’t seem to matter which one is where, especially when the train comes to a spot where the extra power is really needed. And I’ve used them on the headend, as pushers, or spaced throughout the train. If you’re going to use two or more locos on one train, and they’re not coupled together on the headend, it’s more important that they start moving at approximately the same throttle setting. The longer the train gets, the more slack you’ll have to contend with, which can cause lots of problems if one of the locos is balky. If they’re both on the front end, this is less of a problem.
Doh! I guess I’m SOL trying to run a long coal train with pushers and the prototypically correct Athearn SD40T-2’s!!! I do plan on running DCC thank the Lord!
I see no reason why a bunch of Athearn SD40T-2s won’t run well with one another on DC. They’ve all got the same motor, same gearing, and same size wheels. [swg]
Unless any one of the engines has the ability to pull the entire train with no slippage, they are all going to be going the exact same speed, so it does not matter. I run only DC. As long as the locos are remotely close and I am not trying to run a scale 100MPH (which I am not), I have has no problems.
I don’t push trains so I can’t comment about adding a pusher but I can comment about pairing engines as a consist in DC. Over the years a lot of unwritten rules about doing this have become gospel and most are a myth. Some of the typical comments have been posted previous to mine. One of the big ones was you would burn up motors in the faster engine as it would overheat. A couple of times ago this topic came up I stated that wouldn’t happen and challenged anyone who had the problem to come forward. No one did. I don’t think you can do any harm or have any problems other than possible jerkiness between engines regardless of where they are placed. In that event I would try a different placment and enjoy my railroad.
They may very well have the same motor and they may very well have the same gearing and they may very well have the same size wheels but I doubt sincerely that the have the same FRICTION! Anybody here ever encounter anything other than close-but-no-cigar circumstances of two locomotives running at identical speed?
concretelackey,
pushers may be possible with DCC but I would hesitate to attempt pusher operation with DC unless I was using VERY broad curves - that’s going to be a scale four-hundred feet radius - and I knew that my trackwork was ABSOLUTELY POSITUTELY level; sooner or later your head-end units are going to encounter a grade or a curve or some other friction creating circumstance which will cause them to slow down. It doesn’t really take much of a grade or a curve to have an effect on a locomotive/locomotive consist but the pusher doesn’t see the same friction and keeps shoving with the potential for catastrophic events.
You can put three - or more - locomotives - and they don’t have to be all by the same manufacturer - on the same train and get smooth operation. What you have to do is to trick them into running at the same speed.
We have three locomotives - #1, #2, and #3. We determine that at a no-load speed AT A GIVEN VOLTAGE #2 is the fastest and #3 is the slowest. Arranging our lokes on the track in the order of #3, #1, and #2 we hook up a train to the drawbar of #2 loke and crank up the power supply to THE GIVEN VOLTAGE. We keep adding - or maybe taking off cars - until the weight of the train loads loke #2 down to a speed that is slower than loke #1. We now couple loke #1 to loke #2 and commence adding cars until loke #1 plus loke #2 loads down to a
I have some of the Athearn Blue Box SD40-2 and they run fine in multiple (2, 3 or 4) unit lash ups in both DC and DCC. In fact, the units are too much power so I have pulled the motor out of the middle unit in a three unit lash up.
I have a set of PK2 SD-60 and one pulls just a bit stonger than the other. They are DCC with the same type of decoder. I have tried setting them to the same decoder number and it doesn’t help. I haven’t got arrond to trying speed matching.
On my last layout I operated an ABBA lashup of Vrney FAs and an AA lashup of Athearn PAs in DC operation.
The secret is that they all get the power. If there are dead spots, at frogs for instance or dirty track, then each loco would lose power as it went over it and and the wheels would be dragging.
I solved the problem by running wires between each loco so that all wheels were feeding power to all motors all of the time. Never had a problem after that. Those FAs could have pulled the basement walls down.
DCC is the best solution if you want to simulate a helper operation. A loco that’s too fast at the back will cause the train to buckle, one that’s too slow will increase the risk of a string-line scenario.
With DCC, you can control each engine or group of engines independently, on some systems you can do this from the same hand-held throttle. I have a pair of FA’s rigged up as helpers, with a non-functioning coupler on the front end. That allows the push from the rear to be effective, and when the train reaches the summit, I just slow down the helpers, and the train rolls off on the fly. I can then reverse the helpers, and send them back down the hill to wait for the next train.
DISCLAIMER: This post is designed solely for the statement of facts as demonstrated in my own personal experience. It is in no way an indictment of DC control or those who choose to use it. Any misinterpretation of this post to the contrary will be met with a barrage of pointless lawsuits and dozens of flaming posts from people who thought we were talking about flange depth, 4x8 layout planning, or the use of artificial plantings in a garden railroad.
Well, I don’t raelly plan on doing helpers much but that could change. The Rio Grande used helper alot on 3 different locations: Tennesee Pass, The Moffat/Craig Branch and Soldier Summit. Rio Grande used F units as helpers in the 60’s, and in the 70’s GP40’s and GP30’s were common, and later SD40T-2’s. SD50’s were also mixed into helpers in the late 80’s and beyond.
Two of the same units from the same manufacturer do not always run the same or even close. When I got my GP40x’s one ran what I considered great. Could crawl, was quiet, maintained a constant speed well. The other? Well let’s just say it had problems. Normally I’d try to fix something like that, but since it was new, I called Athearn.
Athearn sent me a new motor no problem. The new motor was so nice it made the other loco, which runs well, look like there was something wrong with it.
Same loco, same gears, same wheels. It’s just the way it is.
riogrande5761, if you use DCC then it should not be a problem to speed match your locomotives. For people like myself that run on straight DC it is rather frustrating to use say a GP30 and a GP9 made by P2K in a multiple unit lash up. This is due to the flavour of the month model gear ratios used by P2K.
As for Athearn, all three engines of mine run at a totally differnt speed at identical throttle settings. Given todays technology it is a rather sad statement for this manufacturer as well as P2k. Specially when Kato and Atlas do not have such problems and the locomotives from either manufacturer run at almost identical velocities and can make for interesting lash ups.
They may very well have the same motor and they may very well have the same gearing and they may very well have the same size wheels but I doubt sincerely that the have the same FRICTION! Anybody here ever encounter anything other than close-but-no-cigar circumstances of two locomotives running at identical speed?
concretelackey,
pushers may be possible with DCC but I would hesitate to attempt pusher operation with DC unless I was using VERY broad curves - that’s going to be a scale four-hundred feet radius - and I knew that my trackwork was ABSOLUTELY POSITUTELY level; sooner or later your head-end units are going to encounter a grade or a curve or some other friction creating circumstance which will cause them to slow down. It doesn’t really take much of a grade or a curve to have an effect on a locomotive/locomotive consist but the pusher doesn’t see the same friction and keeps shoving with the potential for catastrophic events.
You can put three - or more - locomotives - and they don’t have to be all by the same manufacturer - on the same train and get smooth operation. What you have to do is to trick them into running at the same speed.
We have three locomotives - #1, #2, and #3. We determine that at a
It is sad indeed. Athearn has always came up a bit short on drives. But I need those SD40T-2’s and SD45 with the correct details so I’m stuck with them. Same for GP40-2’s - no one else makes’em.