726 (1946) armature end play

I have a ‘46 Berk I’m working on that runs good forward, but is much slower and noisy in reverse. So I was wondering:

1) How much endplay should there be in the armature shaft? Mine has about 1/8”.

2) How much end play should there be in the lower horizontal worm shaft? Mine has about 3/16”.

3) What is the proper length of the brushes and brush springs? 

Thanks,

AC

Original Post

End play on the armature is not too much of an issue since it drives a spur gear.  You do not want so much end play that the commutator will hit the brush holders.   This problem is not easy to correct as the pinion is pressed on the armature shaft.  

On the worm shaft end play, this is controlled by steel balls in each bearing block. I have never seen them missing or with wear on them, but you might check. I think the important thing is that end play does not allow the worm wheels on the axles to get in to an area on the worm shaft where the worm is not fully cut. 

On the brushes, I am not home now so I can not look up the proper brush length. Hopefully someone else will post this data. They are the 2020 brushes, which are quite long.  

For this problem also look at the side play in the driving axles. Since these wheel sets go in from the bottom and do not require pulling wheels, they are easy to check.   Frequently when the current collector is removed, which is what retains the driving axles, the four ceramic insulators are broken. I would suggest you have a replacement set prior to taking this apart. 

also a lot of times the brushes wear on a angle and might create an issue when changing directions. also helps to polish the commutator with emery paper very fine grit and clean out the gap between the segments. and then take a tooth pick and  clean  out the gap it builds up with carbon threw time especially the old post war engines  Lionel. also some  times u need to replace the springs n brushes. if the brushes look like there long enough but are worn on an angle you can use emery paper until there straight again  . springs can loose there tension which can cause your issue as well!

On the worm shaft end play, this is controlled by steel balls in each bearing block. I have never seen them missing or with wear on them, but you might check. I think the important thing is that end play does not allow the worm wheels on the axles to get in to an area on the worm shaft where the worm is not fully cut. 

I have seen bearing blocks that had visible flat spots worn into those steel balls. Unfortunately, I do not know of any way to remove / replace the balls. I don't even think they can be turned.
I guess the question is whether they are worn enough for the end of the shaft (the part not cut down) to rub against the face of the bearing block.
If anybody has a technique to replace those balls, I'd like to read about it.

If the end of the shaft was rubbing on the face of the bearing block, I think I'd try to find replacements, or perhaps put a thin nylon washer between the shaft end and the bearing block.

Another suggestion: Check whether your side rods binding in reverse.
I think it is possible for them to be OK going forward, but binding backwards due to slop in the drive train.

Factory spec on the brush: .4687 inches, including stepped portion
Factory spec on the brush spring: approx 1.000 inch.

C.W. Burfle
romiller49 posted:

I’m not a post war guy but 3/16 is most likely way too much. I really think the worm shaft should be not much more than 1/32 inch. I’m sure someone here will supply the proper clearance. 

My end play on the worm shaft equals half the width of the spur gear that is driving it from the armature shaft! The bearing blocks ‘lock’ into the chassis so shimming them isn’t possible. When the worm shaft bottoms out at either end of it’s travel the worm isn’t rubbing the bearing block so the ball bearing must be doing its job. It’s just weird that there’s that much end to end movement of the worm shaft.  This is my first and only ‘46 726 so I have no way to compare it to another. I could examine a ‘46 671 or 2020 I have and see how those compare, but the chassis is different. Regarding shimming, I wasn’t able to find a shim with the correct ID/OD since the OD is restricted by the chassis bosses that lock the bearing blocks into place.

Thanks for the reply

AC

C W Burfle posted:

On the worm shaft end play, this is controlled by steel balls in each bearing block. I have never seen them missing or with wear on them, but you might check. I think the important thing is that end play does not allow the worm wheels on the axles to get in to an area on the worm shaft where the worm is not fully cut. 

I have seen bearing blocks that had visible flat spots worn into those steel balls. Unfortunately, I do not know of any way to remove / replace the balls. I don't even think they can be turned.
I guess the question is whether they are worn enough for the end of the shaft (the part not cut down) to rub against the face of the bearing block.
If anybody has a technique to replace those balls, I'd like to read about it.

If the end of the shaft was rubbing on the face of the bearing block, I think I'd try to find replacements, or perhaps put a thin nylon washer between the shaft end and the bearing block.

Another suggestion: Check whether your side rods binding in reverse.
I think it is possible for them to be OK going forward, but binding backwards due to slop in the drive train.

Factory spec on the brush: .4687 inches, including stepped portion
Factory spec on the brush spring: approx 1.000 inch.

I think new springs and brushes are in order since a well worn brushes and/or weak springs could cause the commutator to push into the brush plate. Maybe this is what’s happening when reversing the loco? Just measured the springs at 1 inch and the brushes at 0.380. I’ll try and get to my LHS Monday — he carries Lionel parts and will hopefully have them in stock.

Thanks for the reply,

AC

Gentlemen,

Went to the home of a friend and longtime Lionel collector and examined his ‘46 Berk. That crazy amount of unnecessary endplay was present on his too. Guess it is what it is. I have two ‘46 Turbines requiring tuneups as well so I tore them apart. The worm shaft in them has noticeably less endplay. Also measured the brushes and they were approximately 0.430. So I’ve ordered 3 pairs of brushes and springs from Brasseur’s. Unless I post again I’m going to assume replacing the well worn brushes (0.380 vs. factory 0.4687) on my ‘46 Berk resolves the poor operation in reverse.

I thank all of you for your input,

AC

Don't discard those old brushes and springs, especially if they are copper colored original Lionel parts.
Don't know about the ones from Brasseur, but many of the replacement brushes and springs that are available today aren't that great. Springs with the wrong tension. Brushes with too much resistance and/or too hard.

You might be better off with what you have.

C.W. Burfle

Gentlemen,

Here’s an update. Received my parts order from Brasseur’s and the replacement brush measures 0.470 and is carbon, but turns out I only ordered one! Overlooked this as I ordered other parts as well.

But! In the middle of the night I woke up and the solution to the excessive worm shaft slop hit me! I was able to use a pin punch and tap the ball bearing into the bearing blocks so as to get the spur gears exactly centered on each other with just slight endplay. I put some epoxy at the rear of the bearing blocks so as to keep the from migrating and creating slop in the shaft again. Tomorrow  I’ll file the back of the bearing blocks flush, drop the worm shaft back in and see how she goes. Temporarily I’ll use the longer brushes from a ‘46 Turbine.

AC

P.S. It would be awesome if someone made brushes of the same material as the originals. Anyone have a source?

 

I was able to use a pin punch and tap the ball bearing into the bearing blocks so as to get the spur gears exactly centered on each other with just slight endplay.

I think that it is more important that the head of the armature be in the correct position between the field. The spur gears have flat teeth, what does it matter if they are off center a bit?

I was thinking that you moved the motor bearings. Interesting trick. I am going to  try doing this the next time I see a worm shaft with a lot of play. Worm shafts were used in the 1946 Berkshires and Turbines, as well as in the earlier F3's. 

Brushes: yes, it would be great if someone made brushes to the original factory specs, or at least got them as close as possible.
The brushes I last purchased from Lionel are probably the worst, as far as resistance goes.
Over the years I have also wound up with brushes that were much too abrasive to use.
I have a box of brushes that I would never use. I don't know why I keep them.

Coil springs of all types (not just brush springs) are an issue too. Many times the springs are physically close to the dimensions of the originals, but have a different stiffness / tension. I assume this is due to them being made from a different material.

C.W. Burfle

Gentlemen,

Success with my method to take the slop out of the horizontal worm grear shaft and getting the spur gears fully engaged. The ball bearing on one bearing block had to be pushed in much more than the other. Filling the gap created at the rear of the bearing blocks will keep the problem from reoccurring.

As a final performance enhancement I resurfaced the commutator. Very fast, smooth and quiet now. Wouldn’t know it’s the same locomotive I started with.

AC

 

Harmonyards,

Mechanically I’ve just repositioned the ball bearings inside the bearing blocks at the end of the horizontal worm shaft. They are a friction fit inside the blocks. I was able to tweak the position of the ball bearings so the spur gears would fully engage. Once I achieved the correct end to end position I locked the bearings in place from the rear so they couldn’t get pushed deeper back into the bearing blocks. A pic really wouldn’t show anything as the ‘fix’ is hidden. Before this tweak the spur gears would only mesh on half their surfaces due to excessive end play.

Just as an aside, my two ‘46 Turbines have very little endplay on the horizontal worm shaft and their spur gears align correctly.

AC

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