# Alco Diesel Service



## Nuttin But Flyer (Dec 19, 2011)

I serviced my #472 Alco Diesel last night by tearing down the motor and cleaning all parts of it. When reassembling everything, I noticed a small black square part with a slight curve on one side and a dimple in the center of it. This piece fits inside the motor housing, inside a cavity at the end of the armature and acts, I guess, as a shim or thrust spacer plate. However, I only had one -- the one for the other end is either lost or was never there. When I checked the exploded views from Gilbert's service manuals, these pieces do not appear, nor does anything appear in the parts list that might remotely match a description of these items. Can anyone shed some light on these items -- what they are, their part number and if someone like Portlines has these for purchase? Thanks.


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## gunrunnerjohn (Nov 10, 2010)

Sounds like something you might be able to fabricate for yourself. Have a picture?


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## tjcruiser (Jan 10, 2010)

Nuttin But Flyer said:


> I noticed a small black square part with a slight curve on one side and a dimple in the center of it.


I'm not an AF guy, buy you're description sounds a bit like a brush for a modern motor ... curve to ride up against a spinning round armature commutator, dimple for spring on back face, etc.

Maybe ???

Maybe it doesn't go to this motor, though ... maybe it just got "sucked up in there" along the way ???

TJ


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## gunrunnerjohn (Nov 10, 2010)

You're right TJ, could well be a brush. If so, and the locomotive runs, it's clearly not part of this one! 

I'm curious about the one that is there and what it's doing in that case. That's why I spoke of a picture.


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## Nuttin But Flyer (Dec 19, 2011)

No guys -- def. not a brush. I have the brushes in place. These items are located at each end of the armature on the AF diesels. They appear to be a small black plastic square, maybe 1/4" square and very thin. There is a cavity machined in the motor housing for these pieces to be inserted. I have one of them, the other is missing. I tried to include a photo that Reckers once posted when he was servicing a diesel and I'll try to describe where they go as they are not very visible in the photo. At each end of the motor housing there is a single screw hole which is used to fasten each gear cover over the gears. If you look closely, you will see a very small vertical "notch" or "slot" in the motor housing adjacent to each screw hole inside the gear cavity. There is a very thin black piece inserted there which acts like a shim or thrust plate, perhaps even a "bumper", when the armature moves forward and back in the housing. The pinion ends must contact this item preventing it from hitting the metal sides of the housing and causing damage or creating metal dust. That might be why there is a dimple on each of these. For whatever reason, the bottom of these tiny slots are curved -- no doubt from the machining process that created them -- therefore the pieces also have a slight curve to fit this cavity. Hopefully, this has explained what I am in search of resolving.


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## tjcruiser (Jan 10, 2010)

Flyer,

You mentioned Reckers' thread ... that's a good one ... I was looking at it earlier today ...

http://www.modeltrainforum.com/showthread.php?t=4785

Perhaps some photo detail in there that could help? Note his exploded-view scematic diagrams, too. Your description certainly sounds like the part-in-question would be a thrust bearing.

I don't see that part shown / identified on Reck's schematic. Are you sure yours is original, rather than a post-life retrofit by some prior owner ???

Why not try to make the missing one out of some styrene or a freebie "credit card style" hotel key ???

TJ


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## santafe158 (Jul 14, 2010)

I think you're talking about what Reckers referred to as a "bearing cover" in his thread shown in these pictures mounted and removed.


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## Nuttin But Flyer (Dec 19, 2011)

I suppose I could make them, but I have to imagine somebody sells repros of these items if only I had a part number. They surely can't be expensive. Going to York TCA Train Meet tomorrow and will ask several vendors there. If I get the answer, I'll post it here. Eventually, I'll get to the bottom of this mysterious part. Thanks for all the help.


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## tjcruiser (Jan 10, 2010)

Flyer,

Is Santa Fe correct? Is that what you're talking about ... the two end-notched bits shown in Reck's photo, above?

Per your prior description, it didn't sound to me like that's what you were talking about at all. Rather, per your descrip, it sounds like the parts in question go where I've drawn the red circles ... right? ...










TJ


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## phmo (Feb 2, 2012)

The part is a thrust washer. The dimple is not machined into the part. Purpose is to keep the armature centered within the field. Because the drive mechanism uses worm gears, the armature tends to shift back and forth depending on the direction of rotation. The dimples are caused by the ends of the armature shaft rubbing against the washer. Port Lines has fiber replacements for $ 0.99. I suggest you just slip it into the slot in the frame and check the end play in the armature by moving it back and forth in the frame. there should be very little play if the washer is not worn out. Originals are metal according to my experience with six of these units. To my knowledge there is no Gilbert number for this part.


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## Reckers (Oct 11, 2009)

phmo said:


> The part is a thrust washer. The dimple is not machined into the part. Purpose is to keep the armature centered within the field. Because the drive mechanism uses worm gears, the armature tends to shift back and forth depending on the direction of rotation. The dimples are caused by the ends of the armature shaft rubbing against the washer. Port Lines has fiber replacements for $ 0.99. I suggest you just slip it into the slot in the frame and check the end play in the armature by moving it back and forth in the frame. there should be very little play if the washer is not worn out. Originals are metal according to my experience with six of these units. To my knowledge there is no Gilbert number for this part.




That's excellent information: thank you for posting it.

Reckers


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## Nuttin But Flyer (Dec 19, 2011)

I was referring to the slots where the circles are drawn......

I went to the York TCA Show on Saturday and spoke with Doug Peck from Portlines. They are thrust washers and do exactly as suspected, eliminate/reduce the fore-aft movement of the armature. He had some there and I picked up a few for replacement and extras for inventory. Not sure what they cost as I bought a whole bunch other stuff at the same time, but probably 99 cents, as someone suggested, is a good estimate.

I also had sent a message to Tom Barker who responded with the most economical solution -- simply make my own. But I got them from Portlines and am ready to finish my second engine overhaul.

Thank you everyone for stepping up with plenty of assistance and suggestions.

I will be moving on to the next engine overhaul momentarily -- not sure which one just yet. My 334DC 4-8-4 or my 342AC 0-8-0 switcher? Or do I continue with the diesels in my shop -- the 474/475 Rocket or another Santa Fe 360/364, 470/471/473?

So many locomotives....so little time.


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## tjcruiser (Jan 10, 2010)

Thanks for the follow up / info confirmation.



Nuttin But Flyer said:


> I also had sent a message to Tom Barker who responded with the most economical solution -- simply make my own.


More good uses for free credit-card-style hotel keys!

TJ


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## gunrunnerjohn (Nov 10, 2010)

gunrunnerjohn said:


> Sounds like something you might be able to fabricate for yourself. Have a picture?





Nuttin But Flyer said:


> I also had sent a message to Tom Barker who responded with the most economical solution -- simply make my own.


Gee, I think someone else suggested that early on.


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## phmo (Feb 2, 2012)

After giving this more thought, you could probably just turn the washer around so that the dimpled surface is away from the armature shaft end.


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## Nuttin But Flyer (Dec 19, 2011)

Yeah, I could have fabricated my own. But I knew I was heading out to the York Show and would see Doug Peck. I figured for sure he would have the part at a relatively inexpensive cost, and he did. As for turning the washer around, yes I'm sure I could do that too. However, I either lost the one or it was never there, so I was still minus one.


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