# Dismantling an American FLyer GP 7 motor



## Reckers

Since mine is all apart and Stillakid asked for pics, I thought I'd assemble it, reverse the sequence of pics, and show how to take this puppy down. The coil seems to be shot: my multimeter shows no current moving from one end of the field coil to the other. Cest la vie.

The shell is already off as we start: I'm going to use my own names for the parts. Here is the truck that contains the electric motor:










Removing two screws at the base of the gray inverted stirrup reveals the brass stirrup. Note the adjustment set screw at the top of the brass stirrup: there is one on either side.










Another view. Note the screw at the bottom of the brass stirrup: I replaced this to hold it together for the photo, but I took it and it's counterpart out when I removed the brass stirrup from the gray metal inverted stirrup.


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## Big Ed

Whats that motor encased in lead?

They sure look odd to me as I never fooled with them.

They would look real good in Alien Green.:thumbsup::laugh:


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## Reckers

Now the screws at the base are gone, and the brass stirrup comes off.










Look at the wire springs at the top: they provide the tension to hold the brushes in place against the armature:










Side view: the green wire leads to a brush on this side:










The brushes and springs mount to a black fiber insulating board, and it to a silver metal bracket that fastens directly above one bearing cover: two screws come out and the bracket and bearing cover come off:










Bracket and brushes gone, truck with both bearing covers off:


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## Reckers

Removing one gearbox cover allows the field coil to be removed. The bearing covers are shown in foregrown, one face up and one down:










Gearbox with armature removed:










Note the bowl-like indentations in the block of the truck: this is where those brass bearings have to go on reassembly:


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## tjcruiser

Reck,

Fascinating photos!!!!

I'm so used to looking at Lionel O motors (and old-school ones, at that), that this AF diesel motor looks like an alien from another planet to me. At first glance, only, though.

Upon closer inspection (via your very clear / detailed photos), the basic and common parts all begin to make sense. A couple of (perhaps obvious) observations ...

Your commutor plate (I think that's the right terminology) is cylindrical, rather than the conventional Lionel disc shape. Looks like it has 3 "poles" or plates, though ... just like Lionel.

I'm really amazed/impressed to see the helix layout of the metal plates composing the armature (in way of the windings). Why helix? After thinking about it for a moment, it seems to me that this would create a more blended magnetic field torque as the armature rotates (spins) in the field ... essentially smoothing out the pulsing power achieved through a conventional (OK ... say it ... Lionel-type) armature. Eliminate the pulse ... smooth out the torque. The magic helix ... ingenious!

Jim had mentioned earlier (in the other thread) about the "two screws used to center the field". I see those now ... the set screws at the top of the brass stirrup. Questions here:

I'm not sure I understand the function of the brass stirrup itself. Is it simply a retainling ring, or does it serve some electrical function? How much play (adjustment) of the field coil is there within the stirrup, and what does tweaking its position / alignment do?

You haven't shown a pic of the field coil, once removed. It appears to be open on the bottom, which would lead me to think that you have a decent chance of being able to remove the old wire, and spool on new wire to the field ... if, in fact, that's the problem with the motor. Much easier to wind the wire on if the bottom of the coil is open, as it looks like here.

Wire color-coding seems straight forward ... green and yellow to the brushes; red and black to the field. Is there an e-unit in this loco to reverse the current flow? If so, reverse current in what ... the field or the armature (brushes)?

I really have to thank you for these detailed photos. I am NOT a diesel guy, nor an AF guy. But if someone plopped an AF diesel on my desk, I would probably be so intrigued that I would want to take it apart, and disect it simply to see how it works.

Thanks to you and the 'net, I can now do that ... without actually cluttering up my desk with any embarrasing AF stuff!

Cheers,

TJ


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## Stillakid

TJ, *"cluttering up my desk with any embarrasing AF stuff!"* That's pretty funny

Considering how intricate the design is, and how smoothly those AF diesels run, I'd think you'd be out shopping for one today!!!!:laugh:

*Len,* thanks for the pictures:thumbsup: Are you going to try and salvage that com? Or are you going to replace it? 

Do you have a wiring diagram/parts schematic? I do if you need it.
The Armature # XA12A062

http://cgi.ebay.com/American-Flyer-...049632?pt=Model_RR_Trains&hash=item3f040f46a0


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## Reckers

big ed said:


> Whats that motor encased in lead?
> 
> They sure look odd to me as I never fooled with them.
> 
> They would look real good in Alien Green.:thumbsup::laugh:


It's a heavy metal casting, Ed---the whole car seems to weigh as much as a brick! It's my understanding alien green is a livery color reserved for Lionel equipment, though.

TJ, thanks for the kind words. It is an interesting design, isn't it? They put a lot of thought into designing these things and the workmanship is excellent. To answer your question, the field's metal frame rests in indentations in the cast block that holds the axles and gears. The brass stirrup slides down over it and the set-screws move it left or right within that block, allowing you to center it around the armature. Finally, when the brass stirrup is fitted into the gray metal stirrup and the horizontal screws are inserted through both, those screws thread into the same cast block, securely caging the field's frame inside both the brass and gray metal stirrups. As you pointed out, once you get used to the idea that the flat armature plate we are used to has been rolled into a cylinder, it all makes sense----I can't blame you for wanting to switch over to AF.

Jim, it is an intricate design, isn't it? I felt like I was taking some conductor's pocket-watch apart! Thank you for locating that armature---I'll call him today, if I can, and see if he has any fields. If he does, I'll get both a field and an armature from him and get this girl back on her feet, again. The frame needs some cleaning, as does the shell, and the knuckles need some graphite, but I've already worked over the non-engine truck and cleaned and regreased what you saw above. I also took a polishing wheel on the Dremel to the metal wheels and pickup shoes. Once I install a new heart and pacemaker, she should roll out of the shed and fly down the track.


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## tjcruiser

Reck,

OK ... this is getting scary. Not only have I been dreaming way too much about my trains lately, but last night as I drifted off to la-la land, I was actually dreaming about YOUR train. Your American Flyer train. Your American Flyer DIESEL train! Sweet dreams? More like Freddy Kruger nightmare!

But I did have an interesting thought ...

Before you read that field coil its last rights, there's one other diagnostic check you might want to do ... in addition to your conductivity test.

Jump in something like a 12V DC power supply to the in/out leads going to the field (with the field disassembled, and everything else pulled apart, not making contact). As you know, the field coil is simply an electromagnet. Now, with DC power running through the coil, stick a small (kids) compass underneath the coil arms. You should see the compass needle align itself strongly with the coil arms when power is supplied, and reorient back to north-south with no power.

It might not work in your case (if, in fact, the field windings are fried). But it's a simple enough extra check before you commit to putting it in its grave.

Sweet dreams,

TJ


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## Stillakid

*parts switch?*

Len, if I'm reading the numbers in your pictures correctly, I think that at some point in time, perhaps some part switching was done. My manual has the truck chassis & wheel assembly for a 372 as part # XA12A074-RP......the field assembly for this chassis is...XA13A036The truck chassis & wheel assembly for a 370 is part # XA12B065-RP...the field assembly for this chassis is...XA11461something to look into before you start buying parts.....Jim


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## T-Man

I love the smell of oil and parts everywhere!!!!!!!


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## Reckers

Teej,

That's a great idea for a test! In fact, just a loose nail or anything that would jump to the frame would give it away---thanks for the suggestion! And please....you can dream of my AF, you can dream about my diesel. But please don't dream about me! Or if you have to, don't tell me you're doing it!


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## Reckers

Stillakid said:


> Len, if I'm reading the numbers in your pictures correctly, I think that at some point in time, perhaps some part switching was done. My manual has the truck chassis & wheel assembly for a 372 as part # XA12A074-RP......the field assembly for this chassis is...XA13A036The truck chassis & wheel assembly for a 370 is part # XA12B065-RP...the field assembly for this chassis is...XA11461something to look into before you start buying parts.....Jim


Jim,

Thank you for pointing that out. I don't know if it's because there are two distinctly different trucks for this one (a lot of difference between them, too!) or if someone's been swapping parts. I may just take the carcass to the LHS and see if they can match the field AFTER I run the TJ DC and compass test!


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## Stillakid

*Just as a reference.............*

I know, I'm a "PITA!" But hey, today's just one of those days where I'm unable to anything else(and I took her computer for the day!)

These are from my manual............

View attachment 4846


View attachment 4847


View attachment 4848


View attachment 4849


View attachment 4850


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## Reckers

Jim, thanks for sharing and for not breaking the wife's pc! I think what I'm gonna do is this: first, try TJ's test for magnetic field existence. If I get no field, that defines the next step: go shopping! I'll call the LHS guy and explain what I have---I'll ask him if he's got a field for 370 or 372 and to bring both to the shop Saturday (he keeps stuff at home and brings in what you request). I'll get a visual match and buy the one that fits!


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## imatt88

As I am searching for a AF engine, I will follow this thread with interest....


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## T-Man

My only question is.... Why does it look like the springs for the brush arms are touching the same metal plate (the coiled end)? Shouldn't that end hang in space?


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## tjcruiser

Good question, T-Man...

In Jim's first exploded view, is the top of part #22 (the spring mount) made of a non-electrical material? In Reck's 4th photo of Post #3, it looks that way. However ...

In Reck's 2nd and 3rd photo of Post #1, it looks like the spring coil ends might both be touching the metal bracket below that, shorting themselves out, maybe?

What'd'ya' think, Reck?

Cheers,

TJ


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## Reckers

T-Man said:


> I love the smell of oil and parts everywhere!!!!!!!


*L* Ain't it grand!


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## Reckers

T-Man and TJ,

When the springs are in place, they are mounted to a black non-conductor similar to very heavy paper and are forced into the shape of a safety pin without the clasp. One end of the spring passes under the non-conductor and points forward; it's tip then curves up through a small hole in the nonconductor and bends. You'll see the two spring-tips just forward of the silver rivet in the center of the black non-conductor.

The free end of the spring is visible above the black non-conductor. It is forced to the inside (toward the rivet), then lowered to engage the inner surface of a bent, brass strip. The strip passes through a slit in the black non-conductor and has the brush at the bottom end. The bends in the brass strip are both to catch and hold the spring, and to hold the brush at the proper height in relation to the armature. You'll note the green brush wire also passes through a hole in the non-conductor and is soldered to the back of the brush at the end of the brass strip. In effect, the non-conductor becomes the pivot of a hinge: the pressure exerted by the spring forces the (upper) end of the brass strip outward and it pivots at the black non-conductor, forcing the brush inward at the bottom end of the strip. This presses the brush against the commutator face of the armature on either side.


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## Reckers

Teej, when it's all properly assembled, the black non-conductor is mounted to the silver frame. That frame is attached to the truck. The outer ends of the non-conductor sit on the metal frame, but it's cut-out and there is only open space beneath the two springs. They touch nothing but the non-conductor below and the brass strips, above.


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## Reckers

imatt88 said:


> As I am searching for a AF engine, I will follow this thread with interest....


Ian, the good news is that an AF steamer motor is far simpler than this one!


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## tjcruiser

Reck,

Thanks for confirming that the brush springs are OK. Good news.

I'll say again that I've really enjoyed looking "under the hood" of this loco via your very clear photos and descriptions.

TJ


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## Reckers

Tim and TJ, thank you both for your kind words. Tim, I'd feel like an imposter if I set myself up as a blogmeister----I've only been involved in model railroading for a brief time. In fact, one year and ten days ago, I signed up at Model Train Forum, wanting to find out what kind of train I had and to see if they still make them. *L* That was a very flattering suggestion, though, and I thank you for it.


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## T-Man

If you wait, you can have blog here. I am. It's on the improvement list.


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## Reckers

Man, that was fast! How did you get it on the list so quickly?:laugh:


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## Stillakid

Len/Tim...........
On the 4 pc. 302, with the lamp mounted to the boiler front, how do you wire the light?
Do you just solder to the base and side?

Thanks!
Jim


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## T-Man

Reckers said:


> Man, that was fast! How did you get it on the list so quickly?:laugh:


I read it somewhere?? :dunno:


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## Reckers

Stillakid said:


> Len/Tim...........
> On the 4 pc. 302, with the lamp mounted to the boiler front, how do you wire the light?
> Do you just solder to the base and side?
> 
> Thanks!
> Jim


Jim,

I'm at work and it sounds like Timboy was right on it, so I'll sit quiet unless you have another issue---I can look at mine when I get home and tell you what I see.


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## imatt88

Reck,

Thats good to know


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## tjcruiser

Dohhh ... when my wife utters the word "Trains", I can assure you that she is most definitely NOT whispering! "Are YOU spending more money on those <dagger> <cyanide> <death-rays-from-her-eyes> <bleepadeebleep> TRAINS again ?!?!?"

Yikes!

TJ


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## tjcruiser

So, Reck ...

You said in another thread that you confirmed that the field was fried. That's good news, I guess ... at least you've narrowed down the problem.

Good luck finding a replacement. And, just for fun, you might want to try rewiring/rewinding the one you have ... if for nothing else, than as an excercise. I've never tried that. I saw T-Man did it in one of his threads a while back.

Cheers,

TJ


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## T-Man

Mine failed. The wire must be exact or you won't have room for the required number of turns.


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## Reckers

I can't help it, Tim---women find the whole train thing irresistable. I'm just the bystander who gets splashed with the effects of their train-lust. 

I considered rewinding the coil myself...about as long as I considered the effects of reaching into the garbage disposal while it was running. *L* I'm supposed to call my LHS guy at noon and see if he has a field to sell me. He keeps the bulk of his AF stuff at home and they have an odd schedule, so this is my first effort to buy one locally. If he doesn't have one, Doug Peck at Portline probably will. Why is it the best sources for repair parts only operate part time and on weird schedules?


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## Reckers

How about Maxim #2: The number of significant variations in a single part is inversely proportional to the interchangeability of said parts.

As for the field, I've already been to visit my LHS guy. He's an old-school guy: insisted that I bring the armature brushes and truck along with the field. He then proceded to evaluate the brushes (good condition), test the armature (also good) and test the field coil (bad) before he'd hand me a part. After that, he handed me two he'd pulled out of two dead units, either 370 or 372 and said, "Take these home. I tested them---they're good. Try them both for fit. If one fits and she runs, send me back the other with $20. If neither fits well, send me both back." You have to admire a man who won't accept the money until he knows the part works. Unfortunately, I left the truck there in the shop and didn't realize it till I sat down to work on it, this morning, so I guess I'll have to call them and recover the truck on Monday. 

As for "It's so simple even Reckers could do it", that's the MTF standard for MTF Level 1 difficulty!


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## T-Man

*T-man Shuffle*

If it doesn't work, Fix it.
If it still doesn't work kick it! 
If it persists, Kick yourself, because you kicked the wrong thing to begin with!


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## tjcruiser

Just chiming back in here, guys ...

A while back, I posted how impressed I was with the helix design of the armature windings on Reck's loco motor. The helix design helps to distribute the power torque generated by the motor more evenly. Very clever design, in my opinion.

Anyway, Choo Choo Greg happened to mention this, in another thread, which I thought I'd share here ...



choo choo said:


> Those are called *shaded pole motors*, and although it's an old time-honored idea, some modern can motors have returned to that clever design.












Cheers,

TJ


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## Reckers

That's interesting to learn. Mine is still not running---the big move put the project on hold. I now have a mountain of boxes and plastic tubs in the mancave, a 4 x 8 table to dismantle and a bench to clear!


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