Multiple Locos, Different Speeds

I am surprised that you able to run them without destroying the traction tires.

 

I have conventional control also, and it probably is not advisable to run engines together that have significant difference in running speeds. Besides damaged traction tires, motor overheating and other mechnical problems could be an issue.

 

I run multiple units using  identical diesel models or steam engines with closely matched speeds.

 

Just my thoughts on this.

I have to go with Charlie on this, I'm surprised you're not at least shedding traction tires.  If you insist on running them together, my advice is to remove the traction tires and let the wheels slip, that'll do a lot less damage. 

 

If these are the models with plastic gears, you don't want to beat them up too much.

Thanks Charlie.  I do share the concern that there could be some potential mechanical problems that would eventually arise--but I wasn't as worried with these as I might be with higher dollar equipment.

 

I sure wish there were a way to readily lash up 4-6 engines and just go.  Or heck--even a switch on the bottom of powered units that would disengage the gears and allow it to free roll so it could temporarily serve as a dummy.

 

Too many locomotives to run, not enough track.  A common problem we all share, I'd imagine.

Thanks, gunrunnerjohn.  One of them is significantly faster than the other two--I'm thinking I may take that one out of the mix.

 

They sure do look purdy all running together, though.

To answer the question first:  I doubt it really matters that much which you put in front.  However, when I do this, I put the fastest at the rear.  My thinking is that it will then be doing the majority of the work of pulling the train, so that will slow it down the most and result in the least difference with the one or two in front, who only have to power themselves or if they have little speed different, help pull the train.  But I don't think it really matters that much. Still, as an experiment, put the faster one at the rear but don't couple the other two to it and see if they, running alone, are now about the same speed as the faster one pulling the train.  If so they leave them in that order.  

 

I doubt you will have any traction tire problems.  Consider this:  many people run powered A-A or A-B sets.  When I uncouple any of my sets and run them at the same time but uncoupled, they run at noticeably different speeds - up to 20% difference, een more in an old post-war F3 set powered A-A set I have.  

 

I even have one all powered A-B-B-A set (four powered BEEFS that individually vary noticeably - about 10-15% in speed when running alone), and I use them as a set to pull a really heavy train where they all have to work hard but I have no problems. They work well together and I have no shredded tires.

 

Given that you have three Lionel GP-38s, all from starter sets, you very likely have essentially three of the same loco.  I think you will be fine.  

I'm not surprised that you haven't lost traction tires and think what you have been doing is perfectly fine and that you can continue.

 

Here's why: The engines may run at different speeds when run light, but when pulling together the efforts of the individual motors even out as they all contribute to pulling the load. It is only when the engines have fundamentally different operating characteristics, like very different gearing or speed control, that problems arise. An example perhaps would be coupling a can-motored engine to an AC open frame motor or a non-speed controlled engine to one that is operating under speed-control, or two speed-controlled engines that are not closely matched in speed. Speed control can gum up the works because instead of allowing the motor to work by effort it commands it to run a set speed regardless of effort, thus setting the stage for engines to fight each other rather than work together. But assuming, as it appears, that these all have the same basic design and motors and  have no electronic speed control, the operating parameters are close enough that you should be able to continue triple-heading your engines.

 

The thing to look for is not different speeds when running light, but whether your engines pretty much start and stop together without too much straining or wheel slippage when coupled together. As long as they are starting and stopping pretty much together without the wheels spinning or any obvious strain (and that's what I would expect with basically the same model), you are OK. Once under way the different individual engine speeds don't matter as the motors all do a little more or a little less work together sharing the load. That's basically what's happening in a dual motored engine anyway-- MTH PS2 and PS3 diesels actually "speed control" the rear motor only -- the front one runs faster or slower on its own depending on load. People ran conventional traction-tire equipped diesels this way for years without problems, and so can you. (Much as I hate them, removing them is said to create different problems).

 

You might see one engine nudge or tug against the others when you first apply power but as long as the wheels don't slip or spin and the consist soon after moves out together, you're in good shape. For these same reasons, the individual engines' order in the consist doesn't really matter. Load is load, and the effort will even out. Even some of my PS3 diesels running under DCS control will gently "kick" the unit just ahead as the consist starts to move out.

 

RM

Great thoughts, thanks for the insight. In particular, I'd not considered how the load would be somewhat normalized across the three locomotives. They do seem to start nicely without struggling against one another--it's only at higher track voltage that there seems to be a noticeable speed difference. I'll keep a close eye on them to ensure there's not too much stress. Thanks everybody.