Is the speed matching done the same as a MU if you are going to use one of the engine as a pusher?
Ken
I hate Rust
Yup. Or you could emulate railroads from before the days of distributed power and have one person run the pusher and another run the head end loco and try to coordinate operation so you don't push the train off the track or stringline it off a curve. REALLY fun to learn all the whistle signals and do it with steam locos assuming pre-radio days so you can't just talk to each other even though you may only be standing a few feet apart - just use the whistle signals.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Yes. When I use distributed power I always use locos that are speedmatched to the lead locos. I sometimes use a loco on each end of a short local freight to switch industries with trailing point and facing point sidings without having to turn the train. Speed matching makes it work out well.
Thank you all for the answer. I was pretty sure it was done that way.
Ken - I have the same question. The 3 replies so far don't really give me a 'warm feeling' about it. I've not done this, so I'm not speaking from experience here - other than lots of experience 'tuning' other electronic equipment - sometimes a very frustrating experience.
The problem I foresee is that locos in different places in a train - especially a long train - typically do *not* see the same mechanical load. Speed matching (no load) will not correct for load mismatch, or for the differences most locos have in pulling vs. pushing.
If one could do the speed matching under the same or similar loads that will be experienced by the train in question, then I would believe it would work pretty well. However, most trains will probably differ from each other. Or maybe one could run the loco setup in pretty much the 'same' kind of train, and match them that way, if possible.
When locos are used as pushers & pullers, after no-load speed-matching, the load differences may not be readily apparent. This does not mean there are no significant differences. Maybe the important thing to observe is only whether there are stringlining events or other derails.
I guess Armstrong's old addage, 'mock it up on some track and try it out' on your own layout, is the best approach. Of course, this may amount to building a large part of the layout anyway.
Sorry for the long-winded diatribe. I'm just trying to put my thoughts in order on this subject, and I'd bet it's not as simple as many people make it sound.
Good luck.
Dick Chaffer / Bozeman
Well, I have not had the need to do this yet, but...
If the pusher and puller are relatively well speed matched with no load, they will split the load of the train because they have to. It's true that it might not be half and half, maybe not really close, but the effect will be that some portion of the train is being pushed, and some being pulled. In a way, it will be like two trains that just happen to be running with the cars in the middle touching couplers. At different speeds the balance between pushed and pulled cars might change, but that shouldn't be an issue at all.
Jeff But it's a dry heat!
If there is only one operator, I'd recommend double-heading and have those locos speed matched. With a pusher, I'd use two operators and speed matching would be unnecessary.
If using a pusher with a single operator, it would be extremely important for the locos to be well speed matched, especially at starting and lower speeds. Still, you could run into problems when one engine's load is on a different grade than the other, placing highly variable loads on the engines and train. If one is clever/handy (unlike me), maybe a single operator could control each locomotive separately.
If a mid-train helper, the helper should be pushing some of the cars since if the lead engine is pulling on the helper, the train will likely stringline/derail.
Mark
I run on a layout that uses helper service. When running the helper, it is important that you watch what is happening and adjust. Your job is not to match speed as that does not take any load off the lead engine. A helper has to push to help. When you push, the load decreases for the pulling engine and it moves faster and you have to adjust again.
And as Mark has pointed out, the grade can vary from tip to tail.
Chip
Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.
Thanks for all the answers. Part of the train will be going up grade while the half will be going down grade. I can control each engine with my DH 400 with no problem. Will try it first with the speed matched engines and see what happens.
Thanks again, Ken
Hi!
While my layout is not yet at the point of dealing with "pushers", I figured that I'll handle the diesels & steamers differently.
My diesels (1st generation GPs, Fs, Es, PAs, & RSDs) will typically work together, and I've given those is a typical consist (ABBA) the same ID. Note I've tested them separately and they run pretty close together with very similar handling characteristics. In short, I doubt I'll be using diesels as back end (or mid train) helpers.
The steamers are a different story (BLIs & Spectrums), and my thought is to emulate the prototype, and run each separately. I suspect only two will be involved at a time, so the DT-400 throttle should work just fine. I have experimented with this and it gives one a taste of "real" railroading, especially if the train is long enough to truly need a helper.
ENJOY,
Mobilman44
ENJOY !
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
My hippie days must be lingering.. I was thinking of the song by Steppenwolf.
Marlon
See pictures of the Clinton-Golden Valley RR
Hi gents, after lecture of your comments on this issue I am amazed. I am running an oldfashioned straight DC N-scale layout that has a rollercoaster terrain, so there is a genuine need for using at least 2 locos in any decent sized consist. My local, usually anything between 8 and 14 cars, is powered by 2 SW1200 or MP15 type engines, typically 1 of those on each end, so you could say I use helper service. I can assure you that in DC it is not really possible to exactly speed match 2 engines, and fact of the matter is that even 2 identical models from the same manufacturer differ in motor characteristics quite a bit.
However I haven't had any trouble with my trains, derailments do occur once in a while but not normally caused by the drawing or pushing forces of the engines but rather at some turnouts on the older part of my layout, you could say they represent some design/construction flaws.
So how come that it so so important to speed match locos in DCC mode?
I have 3 BLI SD-40-2's Paragon's that suprisingly are an almost perfect speed match by some fluke. I took them to my friends layout and we loaded them up until the train stringlined with 54 cars behind the 3 engines. So being crafty guys we put one on point, one at 40 cars and a pusher all in a consist. We then started loading on more cars in front of the pusher until we had 77 cars, had to pull the grade and that was max.After watching it run the entire layout 5 times we figured we had it all right, and we were happy with the world.
KiwigerdSo how come that it so so important to speed match locos in DCC mode?
From what little I know, so you don't over work one of the engines, over heat its decoder and have it BBQ on you. When I was DC, you put the faster engine in front and all was good. Lot harder to burn up a motor than a decoder.
Well Ken it looks like your question was answered but I thought I would share my observations. I do not run helpers on my 2% grade but may add it for operational interest, but the grade is only about 30 feet long in N scale. On our freemoN layout where there are no planned grades a few guys have been running helpers for added interest and I was shocked as to how smooth they ran with few issues from the pusher derailing any cars. Makes me want to try some on my home layout the more I see them run. Now in Pomona the floors are made for allowing good drainage so grades are as high as 4% if the layout is assembled to match the floor, and I thought the pushers came in reel handy.
Now I would think that you should turn off BEMF entirely so that your pusher does not take off on a grade while your leed locos back off at the sumitt. I have yet to try this but it sounds right. Any thought guys?
John
I wouldn't turn off BEMF. BEMF maintains speed constant regardless of load and/or grade, so when the lead engine gets to the sumit, it will back off to maintain speed while the pusher will indeed increase its power/voltage to maintain speed. I have two Trix Big Boys which have BEMF and are extreemly speed matched. I have a double helix that goes 4 times around with 71 Feet to go up in a 2.5% grade. I've had a 60 car train go up with one Big Boy at the front and one Big Boy pushing (in front of the caboose of course) with no problems. All my diesels run in pairs (electricaly connected with micro0connectors), so they normally handle normal length trains easily. The 60 car train was made up just to tease the Big Boys...
If we are talking a true pusher operation here, so far as I'm concerned there should be no speed matching nor back emf operation. It should be the pusher engineer's job to apply or decrease power to his locomotive as required to get the train up the hill. And since the pusher engineer is the guy standing in the aisle (on our model railroads), he should be watching where the slack is in the train to verify that he is doing his operating correctly.
Didn't read the whole string but I have had so much trouble "speed matching" locomotives (I even have a "matched set" in which one always pulls away from the other) I now use dummy locomotives. No separation problem there and the setup still looks good. As you may have also guessed, I do not use DCC.
DRGWBuff2000 I wouldn't turn off BEMF. BEMF maintains speed constant regardless of load and/or grade, so when the lead engine gets to the sumit, it will back off to maintain speed while the pusher will indeed increase its power/voltage to maintain speed.
I wouldn't turn off BEMF. BEMF maintains speed constant regardless of load and/or grade, so when the lead engine gets to the sumit, it will back off to maintain speed while the pusher will indeed increase its power/voltage to maintain speed.
I do agree in theory but most of my clubmates use Digitrax and the decoder shuts off Bemf when consisted and they are successfull, but there are only slight grades.
I agree with Maxman that to add an engineer to run the helper indipendanty would be the ideal but many of us are not at a point in the hobby to have multiple operators, so the one man train crew has control of all the locos in the train.
Website: http://bobfrey.auclair.com
Hi again!
I very much agree with Maxman, in that there should be no electronic speed matching for a pusher loco. Most of us strive mimic prototypec RR operations, and I believe that operating a pusher loco, under separate control, is as realistic as we can get. Also, it can be extremely challenging and a whole lot of fun too.
My diesel lash-ups (F unit ABBA all powered, or E unit AA both powered) can pull anything I can throw at them with the biggest challenge running up the very long winding 2 % grade from the lower level staging area. But my steam locos are a different matter. While the BLIs pull pretty good, it takes two (2-10-2/4 or 4-8-4) to get a 25 car train up the grade. I typically set the lead loco on an appropriate speed step, and operate the pusher (using a DT400 Digitrax 2 loco throttle) to match. Now to me, this is FUN !!!
Just my take on the subject!
spidgeI agree with Maxman that to add an engineer to run the helper indipendanty would be the ideal but many of us are not at a point in the hobby to have multiple operators, so the one man train crew has control of all the locos in the train.
You said that you use Digitrax. One of the "advantages" to this system that seems to get a lot of play around here is that you can operate two loco sets with one handset without switching back and forth. So I don't see why one person cannot, without a little practice, operate both as the lead engineer and the pusher guy.
I have a Aethern Genesis Big Boy with factory sound, and a Bachman SP Daylight steamer with Tsunami 1000 sound that I tried to speed match. The Big Boy pulling and the Daylight pushing at the end of a 15-car hopper consist. The curious thing is that the BB was speed matched as best as I can (no load) with a slightly slower speed than the Daylight. When I couled them up and ran them, the BB was pulling away from the Daylight, leaving it behind after decoupling. To boot, the BB was on the up-grade while the Daylight was still on the level. Why would the speed on the BB be higher with a significant load than no load?
Any thoughts?
Tammo
Tammo, you said that that you tried to speed match, but the BB has a slightly slower speed than the Daylight (at no load). Therefore, my thought is that your Daylight is not able to push a 15-car hopper consist up your hill by itself.
Robert Frey
maxman spidge: I agree with Maxman that to add an engineer to run the helper indipendanty would be the ideal but many of us are not at a point in the hobby to have multiple operators, so the one man train crew has control of all the locos in the train. You said that you use Digitrax. One of the "advantages" to this system that seems to get a lot of play around here is that you can operate two loco sets with one handset without switching back and forth. So I don't see why one person cannot, without a little practice, operate both as the lead engineer and the pusher guy.
spidge: I agree with Maxman that to add an engineer to run the helper indipendanty would be the ideal but many of us are not at a point in the hobby to have multiple operators, so the one man train crew has control of all the locos in the train.
I do agree that with a dual knob throttle that this should be doable with practice. Good idea. On my home Layout I run NCE so would have to toggle using the recall stack. Not impossible, just challenging.
“To add an engineer to run the helper independently would be the ideal”………… I have operated on two HO layouts as a helper. The first trick is, the helper locomotive has a coupler that won’t couple. (The helper can only push.) The second trick is as the helper, you must watch the “slack” in the cars as you help push them up the hill. When the “slack” starts to become closer to the head end locomotive, back off on the helper throttle!
This is a case where the cheapo Kadee clone couplers might come in handy, liek those cheap plastic ones that used to come on P2K locos (before the Proto Max) that had a tendency for the knuckle to get jammed wide open - it wouldn't hook up with anything, and you couldn;t fix it, only replace it. Perfect for the front of a pusher loco so it can uncouple on the fly.
Or a use for the DCC uncouplers. This is one case where you DO uncouple directly at the engine.
This is a short answer for those using DCC decoders with BEMF enabled such as Tsunami, TCS and QSI,
Speed matching only has to be close not exact. BEMF will allow two or more locomotives to operate in such a fashion so they will not push/pull against each other, and in fact allows the decoders to apply enough voltage to the motor that a relatively continuous speed is maintained.
i've had Tsunami, TCS and QSI eqipped locomotives through out trains up to 75 cars in various configurations; double headed with mid-train helpers and pushers on the rear. All works well when the BEMF values are properly set [an easy procedure].
For more in depth and technical discussions of BEMF and what it means for DCC users, go to the QSI or Soundtraxx Yahoo! groups
My own opinion is that BEMF allows for very realistic train operations whether it be mu'd consists or locomotives in helper service.
Erik Fiske
I couldn't fix your brakes, so I made your horn louder