Model Railway Forum

hi, would two loco's with the same model No and class have the same performance. top speed, sound etc.
i would like two bachmann class 20, model No 35-126sf but only if they perform exactly the same. any advise please

More chance of winning the lottery.

I had two pairs of Bachmann CL20’s. The green ones ran perfectly as a pair whereas the blue ones didn’t. For a while the front one was pulling the second one then the second one was pushing the front one. That was DC running. I thought with DCC you can program them to run the same.

so did i, but not fully up to speed on matching using cv's. they frighten me

I would buy one new model and find a ‘selling for spares’ model on eBay and take the motor out.

Or buy two good ones and remove the motor from one to keep as a spare.

I had success with DC using three Bachmann class 03's when they first came out with Bachmann (Mainline had made them before and Bachmnn have made a newer updated version since).
I ran them all in at the same time going in the same direction and now and then I would turn a single loco around. They were all coupled together. With careful running in by doing this, they all ended up running at the same top speed regardless of the direction they were in and all were equally matched.
I may have been lucky, but even the older Mainline ones I later were given ran at not too far off a similar speed.
But unfortunately sometimes life does not always work out like that. I tried to use two Hornby ringfield motors in the same vehicle and they never did run at the same speeds and the experiment was abandoned as they kept fighting against each other which caused de-railments. Admittedly that was with DC, but even with DCC the best chance you are going to get is to buy a pair of the same locos at the same time and run them in the same while couples to each other (That is what I did) and then get identical DCC decoders and hope for the best.
Admittedly one can program DCC settings, but having two fairly equal locos to begin with saves one a whole lot of effort.

My experience is that with double heading with DC that it is not so much of a problem as if the two locos used have a speed difference, as long as it is not too different, and as long as they are pulling a heavy train, if one puts the faster one in front one should not get too many issues as the front loco will just act like it s pulling a heavy train and the rear loco which is slightly slower will be adding nicely to the tractive effort, and they run ok as a pair. The problems one has in this way is if one loco as very much faster then the other and thus is not anywhere near an equal match, as that is when one risks stripping the teeth on loco gears etc!

I did find DCC easier in that one can (If I remember correcly as I have not used DCC for ages) run two locos together but individually as in not in a consist which is easier if one has two hand controllers. Thus with practice one can match the pairs top speed and set it so the faster loco slows a little to limit its top speed on POM, and thus one can run them in a consist together and they should be fairly equally matched. (I usually remove coupling hooks for the test so both locos won't couple while one prorams them). I don't remember which can or can't be done with POM programming, but I do know I spent ages doing things like this! Probably why I decided to go back to DC, as if there was a CV to alter, I would alter it. With DC, I just ran the things and saved myself a lot of hastle!

Motors, like all electrical and electronic components are never the same in their characteristics or performance. For instance in high end audo equipment transistors have to be hand picked in testing to produce as near as possible matches for amplification stages. It's just part of the production processes and very slight differences in quantity and quality of the raw materials. In motors it could be down to a slight variation in the thickness of the coil wire or an extra half turn; it could also be down to the strength of the magnets or amount of friction in the bearings.

For instance I have built a gantry crane using a rack and pinion system where two motors sharing the same power supply pull themselves along two racks about 8 inches apart but due to these slight differences in motor performance they very soon cause the jib carrier to become skewed.

You could try matching locos, like the transistor example above, by taking several out of the box and running them side by side and selecting the two closest performers. But then over time as each became "run in" their speed would almost certainly start to differ and you would be back to square one. So take WTD's and others' advice and have one powered and one "dummy" loco to ensure a smooth ride

I have two Class 20s running in consist no problems at all.
Two Tts sound decoders programmed with the same number working perfect, no push pull.
I think i have been lucky

Bachmann used to make an unpowered CL20.