New to 2 rail looking to learn basics of DC brass steam engine electrics

Hi Howard.

Seems that this is the standard. Even the MTH Proto 3/2 steam locomotives are set up that way -- found that out the hard way when a 3/2 steamer stalled where the insulated rail was shifted from the right to the left -- put the all of the "live" wheels on insulated track.As I recall, the right-hand pickup is on the tender and the left-hand pickup is on the locomotive.

I suppose a tender could be rigged to pick up from all wheels with wipers and double-insulated axles. Steam locomotives would require insulating the tires on both sides and using wipers.

As for couplers, use the Kadee 745 (standard shank/standard plastic box) or 743 (short shank/short plastic box). It's a metal coupler in a plastic box and is insulated from the frame when installed. It's a good idea on brass cars and locomotives as a lot of rolling stock has single-insulated wheels so the body may conduct. I try to keep a couple of pairs on hand for metal locomotives and brass cars. As for diesels, some pick up positive from one truck and ground on the other, while Atlas likes full pickup on both trucks. I haven't done a thorough examination on my Sunset 44-tonner, so I don't know which way it's wired. I want to eventually install either a Proto-3 kit or DCC in it.

Howard,

historically DC steam engines pick up power from the right (+) rail through the engine and left (-) power through the tender. diesels are the same way but in one unit.

the engine and tender are electrically isolated from one another.

Regarding MTH 3/2 steam models, the ones I have converted have a unique arrangement for insulating the drivers.  MTH uses split driver axles with a section of some non-conducting material installed a bit off center on each axle.  The insulation on the axles is off center so that the metal worm gear does not short across the insulation gap when it is installed.  Now , the problem with this is that the side rods and main rods can conduct through the cylinder block and create a short circuit.  So MTH installs plastic bushings in the crankpin holes on the fireman's side of the locomotive.  Axle bearings on the right side of the loco are installed in plastic bushings.

There are spring loaded pickup pins on the engineer's side of the loco frame that pickup power from the right side axles.  It is possible to set one of these up to run on 2 rail without the tender.  I have done that.  Normally though, I insulate the model conventionally with insulated (on the fireman's side) NWSL  wheel sets on the tender wheels and insulated driver tires, the exception being that on the MTH locos, the left side of the engine picks ups power and the right side of the tender trucks picks up the other side of the circuit.  This is done because the left side of the driver axles are grounded to the frame.

Confused yet?  There must be some logical reason MTH did this to allow for 2 3/2 conversion but I don't get it.

Have fun!

Joe Foehrkolb

Wait until I get a photo up to show how Ed Reutling did his engines,

Then again, that's a resin cast engine using Slaters drivers,

Thank You!  I appreciate the information.  With luck (per mwb), it ought to keep me out of trouble for a few of days.

What Joe says.  I sold my MTH drivers and started over.  Yuk.  Also, MTH uses opposite pickup from O Scale standard, as implicitly noted above.  That part doesn't affect anything, but if you continue to use Proto-2, the locomotive must continue to be wired backwards.

Starting over was required also because of the undersize cylinder block, missing tail beam, and open boiler belly on an otherwise pretty darn nice model.

Thanks for the clarifications. I had it backward.

Joe:

Had wondered how MTH handled steam locomotives. Seems like it would have been simpler to just use insulated tires like everyone else. That wouldn't have altered the 3/2 wiring at all. In fact, it might have actually made things easier.

I don't think anyone has ever accused MTH of doing things the easy way or following existing standards.

I can run my MTH J without the tender as Joe describes. I still have the pickup through the tender as well for extra electrical insurance.

Reference Joe F's great post above, the engine trailing truck on my Proto 3 Challenger and GS-4 have pickup wipers on the axles.  What role do they play in 3 rail operation and in 2 rail operation in concert with the Joe's driver info?  Thanks.

 I have a MTH 3/2 Pacific in 2 rail, that glides around the layout and never stalls or stutters, even at three MPH. My Atlas 2 rail switches are just put in place temporarily and not powered at the frogs.

http://www.mthtrains.com/20-3256-2