AF Steamer Brushplates/312

Need some input: have a 312 with brush springs that are "S" shaped and push down on the slot in the brush; can I swap this out with the other design that holds the brush with a coil spring held in place with a cap?  I would believe one can use either one; the brush plates with caps to me are a better design.  Thanks much; Falcon70

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C77176F1-D81F-480E-9B1F-055179DA740FFalcon70 posted:

In my mind it is the phenolic plate at the back end of the armature that holds the brushes against the commutator.  I guess one can also call it the brush holder; Falcon  70

I just dug out the two different armatures, the left one the 11077 and the right one the earlier one. The 11077 has an oil slinger and the early one doesn’t. The other picture shows the early one in the later brush cap and you can see that the brush tubes are making contact with the armature and will short out.

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UK, great call!  Checked the K line overhaul book and the 312 parts break down calls for the later version of brush plate; yet I have the early version on the right; that is what confused me (easily done).  Thanks for the great info; quick question did the 312 without SIT have the newer brush plate (on left)?  Thanks for the great info; Falcon70

 
Falcon70 posted:

UK, great call!  Checked the K line overhaul book and the 312 parts break down calls for the later version of brush plate; yet I have the early version on the right; that is what confused me (easily done).  Thanks for the great info; quick question did the 312 without SIT have the newer brush plate (on left)?  Thanks for the great info; Falcon70

This is my 312AC which is built from 49-51 as were some of the 312 versions. It is a SIB and has the later 11077 with later brush tube assembly.

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The earlier armature can be used with the late brush cap by using spacer washers on the armature, but they have to be small enough diameter to not short out the commutator. I disagree with the observation that the "J" springs are harder to work with than the coils and caps; to hold the spring out of postition for brush install/removal lift them up by the end sticking out of the holder and place them to one side where there is a small V groove that will hold them while you work on the brushes. When you're done, lift them off of the V groove and let them down into the tube.

S'incerely,

David "two rails" Dewey

traindavid posted:
The earlier armature can be used with the late brush cap by using spacer washers on the armature, but they have to be small enough diameter to not short out the commutator. I disagree with the observation that the "J" springs are harder to work with than the coils and caps; to hold the spring out of postition for brush install/removal lift them up by the end sticking out of the holder and place them to one side where there is a small V groove that will hold them while you work on the brushes. When you're done, lift them off of the V groove and let them down into the tube.

Dave is right, you can use washers but it isn’t as straight forward as just building up the space at the commutator end to get rid of it. It is a balance of adding washers to both ends proportionally so that you end up with the brush tubes reasonably close to the armature, something like 1mm is OK as you don’t want to have too much of the brush hanging in mid air and don’t want the brush tubes touching the face of the commutator.

I just had a play with an old chassis and it looks like you would need to build up the worm end to about 3mm and the commutator end about 1mm, but these are just for this chassis and as Flyer chassis are not precision made they will vary and you just need to have a number of washers available in different thicknesses. 

The other interesting point is that the early armatures are 58mm long and the 11077 is 60mm long and what this means is that once you have installed the new later style brush bracket to the older style armature the older style armature shaft does not use all of the new bearing in the brush bracket, it is just a tad short by a mm or two.

Also, as David mentioned, be careful on how you add washers to the commutator end as you can easily short it out if they are too large in diameter. I know of two different early types of armature which on one you could get away with a washer/shim 10mm outside diameter and another which is nearer to 8mm outside diameter. I enclose a picture of both. All in all it is probably better to upgrade to the later armature if you are looking to change to the later brush bracket, the choice is yours.

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Good points, I should have mentioned them. Even if you are using matched armatures and brush holders, ACG limited end-play by using thrust washers at the worm end. I believe ACG had three thicknesses used in a combination to provide some end-play but not too much. You need some clearance as the armature lengthens a little bit as it warms up in use. Don't forget that the late, barrel commutator uses a thin steel washer on the commutator end. Also, the bronze bearing in the holder sometimes becomes loose. You can usually just push it back in, but it it's too loose, you can use a DROP of super glue to hold it in place--both holder and bearing must be clean for this to work. One last, often overlooked part is the felt plug on the end of of the brush holder. This is used to provide an oil reservoir and to keep stuff out of the bearing. The "usual suspects" have this part, although I find them kind of pricey for what it is--I will use a piece of felt scrap and punch out the plug with a leather punch. OTOH, being a piano technician, I have a lot of different felt scraps laying about. . .

S'incerely,

David "two rails" Dewey

Great info David; I do as you stated on the "J" springs; rotate them 90 degrees to lock the small retainer part of the spring in the slot of the brushplate; still not easy for me.  Shimming the older armature for the newer brush plate is a great idea.  As stated, the number of shims for the tolerance is a given.  I do not do repairs on these often and I forget what I have done in the past. 

On the e units, if all the fingers, drum, pawl are intact but the e unit is sticky, I shoot it with WD40, let it soak a bit, cycle it a bit, then blow it clean; works pretty good.  Picked this up many years ago from a good AF tech.  If it does not work then, I take it apart and check for other issues.  Also works well on Lionel e units that look kinda dirty; sometimes it takes a couple of tries but surprising how well they work after a WD40 shower. 

One thing on AF, I am always learning from folks like you; always.   Thanks much for great info; Falcon70

 

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Alan B
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