Question on electrical pickup of MTH 2R Centipede....

SteinzeitOGR Forum Member

....specifically a 20-2200-2 PRR Centipede: This is a trapped axle 2 unit A-A pair with scale wheels ex-factory. I am trying to help a friend troubleshoot one of these by phone and internet.

1. I think the wheels on one side of a truck are insulated at the hub of the wheel on the axle. Electrical pickup is from the wheels on the other side through the wheel bearings to the truck frame. Correct ?

2. If the above is correct, is the truck frame of the F truck +, and the R truck - [ or vice versa, of course ]? If so, is the frame isolated from the trucks ?

3. Or are both the F and R trucks of a unit the same polarity, and one unit's trucks and frame are all +, and the other all - ?

I had purchased the loco for him when they first came out and track tested it, but I don't remember much other than it ran.

Best regards, SZ

3/27/199:02 PM

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bob2OGR Forum Member

If it is like all the others, pickup for insulated wheels is via tiny phosphor bronze wipers. No need, then, to isolate an entire truck. Works ok for a while, then you have to start bending and soldering.

Our final solution - we ran eight hours a day six days a week - was an insulated aluminum block with a pair of brass plungers, actuated by a weak coil spring. But ours was extreme service - we went through axle gears at two year intervals, worms at six, and in one case axle bearings at ten.

3/28/1911:04 AM

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SteinzeitOGR Forum Member

bob2 posted:
If it is like all the others, pickup for insulated wheels is via tiny phosphor bronze wipers. No need, then, to isolate an entire truck. ....

Well, that seems to be part of the problem in my understanding what's going on with this loco. I don't have any MTH diesels, so don't know about the others, but the Atlas ones I'm familiar with use the wiper pickup on both wheels on an axle, since both are hub isolated at the axle. Certainly pickup through the bearings is [ well, generally ] "better" than pickup through wipers. Did MTH use a combination of wiper + bearing in this or other circa-1999 production ?

Anybody out there have a 2R MTH 'pede that can check ?

3/28/194:43 PM

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