Question is i have two P2k’s SD9 upon trying them on the same line a little spaced apart one is just a little faster than the other should the faster one go up front? Also is this hard on engines to do this i do not have dcc yet just dc. Thanks for any advice in advance.
Bruce,
Generally, that will work on DC and not cause any problems. You may have to experiment if you have steep grades to get the best operation under your circumstances. In other words, try 'em the other way if one way doesn’t work.
You may want to check on how much grease is in the gearboxes of each unit. I have heard of instances where the P2Ks have come overpacked with grease; maybe one is that way?
If you had some GPs, I’d ask if things are clicking or not. That’s a sign of a cracked axle gear, but people tend to have more problems with those on Geeps. Just thought I’d mention that.
I have quite a few P2Ks and generally consider them to have been a fairly good deal value-wise. Mine run well together with another of the same. Some issues have been noted in MU-ing with other makes and models. We can only hope that Walthers will put their foot down about that with whoever is doing design and specs for P2K now, but no one is really perfect about that from the factory anyway. It does make a good goal, IMHO.
Mike Lehman
Urbana, IL
Thanks Mlehman, the grease seems to be okay no cracked gears the One is just slightly faster seems like they are geared different from Atlas or Athearns But they will really crawl and pulling power is incredible. These are brand new i have ran some break in time on them picked them up new at Lhs for 50.00 each. I’ll try the faster one up front.
Yes, P2K locos are definitly geared differently than Athearn or Atlas. But even among two identical units, there will be slight variations in speed. Even with DCC it’s nearly impossible to get two otherwise identical locos to run exactly the same speed at every speed step. A slight variation won’t hurt anything - under load it’s more likely that which unit is ‘faster’ will switch back and forth anyway. With just a slight speed difference they shoudn’t buck one another and run fine coupled together. What you can’t really do on DC is mix units with vastly different gearing, like an Athearn and a P2K. You can play games with diodes and resistors to attempt to match speeds, but that’s a lot easier with DCC. Even with DCC they will never be exact, but you should be able to get them close enough to work together.
–Randy
Thanks for the info Rrinker thay seem to run together pretty well,no bucking noticed.does this do any damage to locos?
Since they are production line items there are bound to be small differences. Just like automobiles. as a rule of thumb it is better to put the faster engine first so it can pull the second rather than push it. Years ago it was widely reported that mismatched units would burn out one of the motors but I have never experienced this in over forty years of modeling. I have asked if anyone has had that problem numerous times and no one has ever come forward to substantiate the claim. Therefore I regard it as a model railroading myth. Now I wouldn’t want to put two engines together where one was twice as fast but small differences don;t seem to make any difference.
Bruce, I ran my two BLI SD40-2’s MU’d at our train show, backwards and forwards and round and round, neither of them showed any sign of a problem after quite a few hours!!
They are close but not the same speed wise.
Ken.
Thanks everyone i will pair them up and let them ride.
i to have always ran the fastest loco first followed by the slower ones.some people do it just the opposite and i have tried it but i like putting the faster one on the point.i have a lashup of athearn ,bachmann,and walthers that run very well together with the bachmann’s running just a little faster than the others.terry…
Faster on front, both locos pull all the time.
Faster on rear, the rear loco does all the work (and then some) until the train hits an upgrade steep enough to bog it down. Then, and only then, the slower loco finally picks up some of the load.
That ‘burn out a motor’ story probably dates to the use of AC motors, back about 1940 or so. Modern motors don’t overheat if they are slowed but not stopped.
Check them at different speeds, and in different directions before you decide which is faster.
Some guys start up cold, more internal friction I guess, then run at the same speed.
Some run faster slow, then slow down when running fast. Finally, compare speeds with one in reverse, the other running front forward, then reverse them.
I like to keep a chart with speed comparisons for all my locomotives, so i know what will MU with what, and what will run on the same track for a while without requiring intervention before running over a slower train in front. I suspect drawbar weight will play a part there (how many cars each train pulls) since I have a steep grade, but haven’t had time to set up a test to verify that yet.
Thanks Jeffers-mz Keeping a log is a good idea. i have tried them several different ways as they are Southern roadnames so long hood forward they seem to run real well.
Bruce,
Have the 2 locos been well run and broken in? Many times after just sitting for a period, 2 identical engines that did run well together will need a bit of running to warm them up so to speak.
As to where to place the faster one, I used to always place the faster in the lead, thinking that the couplers would stay stretched for pulling. Now, with running much longer trains, I find that you can have the faster one behind-pulling the weight of the train. This will automatically slow the once faster loco, the slower one out front tends to go along for the ride until it is needed to pull a grade. Experiment with the engines by running uncoupled and see if this will work in your instance. One of my favorite lashups, is running 2 Chessie SD-50s with my Atlas GP-40 coupled to 30+ loaded hoppers. I have run this consist for the past 6 shows, running them for 3-4 hours at a time. So far I have had no problems with any of the locos except for minor lubrication.
Hope this helps.
Bob K.
Today is a blue (and yellow) ribbon day. As soon as I finish running them in, there’ll be four new entries in the log here. Ok, two of them weren’t the two I need to be “finished” buying locomotives, but when the ones you ordered don’t come in and you find a matched set (except road numbers) of Atlas U23B’s in freight warbonnet for $59 each, and you aren’t sure if UPS will make the final mile like they’ve been promising for a week, are you really going to go home empty handed?
I just noticed (re-noticed, you snagged a loco …out west…earlier this week, right? I did an “around the horn” trip a couple weeks ago and only one store in town fits your description, where I got a P2K GP7 two weeks ago, probably off the same sale shelf) where you’re from.
There’s a few others on here, one may have to do some driving, we need to try and link up sometime.