ERR Commander and direction for 2nd powered A unit?

K-Line powered up to six motors with a single motor driver. While you might be able to drive the second unit with the DC Commander in your K-Line engine, it won’t work unless the gear ratios and motor types are the same. You really want to use another K-Line engine. If the Weaver engine works it will be just luck.

Pete

I always make the second unit head backwards and wire it so starts that way.

I also program them with same id #

@Magicland posted:

I have a K-Line E8  A unit which I'd upgraded to TMCC using an ERR DC Commander. Works fine. I'd like to add a second E8 A unit to run as an A-A set to pull my Golden State cars. I have an older conventional Weaver E8 A to use as the subject.

Any ideas what would be the best way to do this? Should it be wired so that the engine starts up in "reverse" (ie., with the cab towards the rear, as it will be while running), or should it be wired with the cab end as the front, like the first A unit? And should the units be programmed with the same ID #, or would it be better for each to have its own?

The 2 units will likely always be run together, and as far as I can see, with the lead unit always at the front of the train.

As long as the gear ratios are close, I'd just run all the motors from the one DC Commander. That way there is no confusion about direction.

You might consider doing a tethered bridge to minimize the issues of the bridge rectifier overheating, that's usually the limiting factor.

Here's one I did on a Cruise Commander, the same technique will work for the DC Commander.

@Norton posted:

K-Line powered up to six motors with a single motor driver. While you might be able to drive the second unit with the DC Commander in your K-Line engine, it won’t work unless the gear ratios and motor types are the same. You really want to use another K-Line engine. If the Weaver engine works it will be just luck.

Pete

Not looking to power the second engine from the first, it'll have its own ERR board.

@Magicland posted:

Not looking to power the second engine from the first, it'll have its own ERR board.

I understand. You can power it any way you want but if the gear ratios are off the two engines will be fighting each other.
It will actually draw less current using a single motor driver vs one for each engine.

First step regardless is seeing how close they run together. You can do that by placing both engines on the track not coupled together, turn TMCC off and see how close they run together at various transformer settings.

Pete

@gunrunnerjohn posted:

As long as the gear ratios are close, I'd just run all the motors from the one DC Commander. That way there is no confusion about direction.

You might consider doing a tethered bridge to minimize the issues of the bridge rectifier overheating, that's usually the limiting factor.

Here's one I did on a Cruise Commander, the same technique will work for the DC Commander.

Wasn't thinking of doing this, but... So this just isolates the bridge from the circuit board, no need for a separate heat sink? And, if I'm not mistaken, I'd just have to run 2 wires to the 2nd A unit for the motors? There's no sound in it, or need for lighting (unless I rig up something for the number boards). Would the motors be wired in series with those from the 1st A unit?

Might end up with only 1 powered motor in the 2nd A unit. At the moment I seem to have 3 Weaver 6 wheel trucks where the motors and the gears only seem to want to play together intermittently (I have 1 set that works fine). Remove the motors from the trucks, the gears turn freely. Apply power to the motors when not attached to the trucks, the motors spin just fine. Put the 2 together, and... nada. Fiddle with them, and they'll run briefly, then again, nada... Gears that meet the motor's worm gears don't appear to be worn.

@Magicland posted:

Wasn't thinking of doing this, but... So this just isolates the bridge from the circuit board, no need for a separate heat sink?

You miss the point of the tethered bridge, you bolt it to the chassis for heat sinking.

@Magicland posted:

And, if I'm not mistaken, I'd just have to run 2 wires to the 2nd A unit for the motors? There's no sound in it, or need for lighting (unless I rig up something for the number boards). Would the motors be wired in series with those from the 1st A unit?

Yep, just run two wires for the motor(s), and they're wired in parallel, not series.  In parallel the master will also run by itself or with the trailing A-unit.  I presume if you wanted number board lighting, or perhaps markers or headlights, you'd just run a couple more wires.

I like the thought of saving one of my dwindling supply of DC commanders (picked up a bunch for a good price at an auction a while back), but dis-assembling a working unit (and pulling the sound board, which is taped on top of the DC commander in it) to de-solder the bridge is probably more than I've got time for this weekend. That and lack of a suitable disconnectable tether on hand, but I may eventually go down that route so I can re-purpose the ERR board.

Hopefully have the motor issue sorted. I notice that there seemed to be a lot of slop in the gears between the center and end wheelsets, they could travel in and out on the shaft they were mounted on. I found some e-clips in the assortment I have that were just the right size to clamp on to the shaft with a bit of pressure (ie., they shouldn't fall off travelling down the tracks), and installed them between the gears and the trucks. After that, the trucks ran fine with power applied to the motors. I'll have to ensure they stay well lubed, but it seems to have done the trick.

I've seen that on a number of power trucks, I use cut down bread closures as shims, they slip right on the axles and problem solved.

Great info GRJ, I never would have thought of bread clips.

Just cut them to size and slip them on.  I've used them for gears and sloppy axles.