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 Post subject: Side bearing identification help needed
PostPosted: Tue Mar 20, 2018 11:59 pm 

Joined: Tue Aug 31, 2004 10:38 pm
Posts: 57
I am trying to determine the proper shimming procedure for the side bearing arrangement in the image below. Currently, the roller does not protrude above the top of the cage. I have been looking on the web to find out what the proper height of the roller above the top of the cage is. I have not found anything that even looks close to this. The number that is cast into the end of the bolster is B7A-03EB MN. The car body will be raised about 3.5 inches higher to get the coupler height at the correct location. I am planning on installing wear plates to the bottom of the car body to also take up some of the height difference.


side bearing.jpg
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 Post subject: Re: Side bearing identification help needed
PostPosted: Wed Mar 21, 2018 8:40 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1291
Location: Strasburg, PA
Raising the car body 3.5"?!? Holy smokes! You will want to look for other problems, and save the side bearings for last. First, be sure that the car springs are not bottomed out, that the coupler carrier doesn't need to be shimmed up, that the car frame isn't bent down, etc. When all those items are in good repair, then look at the platform height of the car (assuming it's a passenger car) to see if you can shim the trucks as needed to get the platform height to match well with the rest of your cars, and if so, will that bring the coupler to where it needs to be?

If either the truck or body center plate is bolted on, a shim can be placed there as needed. A shim can also be placed in the center plate bowl, so long as the center plates still engage by at least 3/4".

Now look at the side bearings.

Sometimes the rollers will get mushed (that's a technical term) flat and not stick up past the body, or someone may have put the wrong roller in at some point. Anyway, cut a new roller from round bar that is big enough to be proud of the housing by a 1/4" or so.

It looks like the side bearing housing is cast into the bolster, and the body bolster doesn't have any shims, is that right?

If raising a significant amount, drill a hole pattern into the body bolster, and use that to bolt the needed shim to.

You will want 3/8" total clearance (3/16" on a side) above the rollers when all is assembled. Do not have both side bearings in contact with the car body at the same time.

"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."
C. S. Forester

Strasburg Rail Road Mechanical Department

 Post subject: Re: Side bearing identification help needed
PostPosted: Wed Mar 21, 2018 9:09 pm 

Joined: Thu Aug 05, 2010 2:06 am
Posts: 164
Hi Kelly,
Thanks for the info so far and here are a few more details. This for a tender that is receiving a truck transplant. The carbody needs to come up to make the deck height and drawbar pocket/coupler reasonable. The frame is straight & square and coupler pocket is back to original spec. The "new" trucks have been rebuilt but the bolsters are just that much lower.
Gratefully acknowledging all the help received thus far.......mld

 Post subject: Re: Side bearing identification help needed
PostPosted: Thu Mar 22, 2018 5:10 am 

Joined: Wed Oct 13, 2004 12:56 am
Posts: 351
Location: Northern California
The cast in lettering you identified is the AAR side frame and bolster interchange code. The B is a bolster. The 7 indicates it is a 70 ton truck with 6 X 11 journals and 33" wheels. The A indicates it has ASF ride control snubbing. I would have to look up the rest of it, but if it fits it probably is not significant. I would suggest you shim the body center plate down with interlocking shims. I would not depend on the bolts in shear in the longitudinal direction. Likewise the body side bearing wear plate can be shimmed down. This can be done with plow bolts except you will need a tapered shim under the nut to accommodate the bolster bottom cover plate angle. The roller can be replaced with a solid or built up block. The roller side bearings never worked well since the rollers always got beaten flat and quit rolling. Make sure to keep the clearances Kelly sited for side bearing clearance. Set the clearance without center plate lube, then put the lube in. It will mash down quickly.

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