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 Post subject: Journal and frame wear on a Brill 21-E truck
PostPosted: Fri Mar 29, 2024 4:21 pm 

Joined: Mon Mar 25, 2024 3:00 pm
Posts: 1
I'm assisting in the restoration of a Brill circa 1913 streetcar. We are making new axle bearings (thrust plate and radial bronze + Babbitt) and traction motor (GE) bearings. A drawing is linked of the frame/axle assembly. The intent is for the restored car to be used in regular service on a tourist line.

There is significant wear of the sides of the journal boxes and significant wear of the slots in the side frames where the journal boxes mount. The issues are what is the appropriate side to side motion tolerance, what is the minimum journal wall thickness, and how we can fix what is needed to be fixed.

The journal box slots for the frame have as cast walls 0.45 to 0.48" thick and the thinnest opposite sides are worn to less than 0.15". Is 0.15" acceptable? If not, is there a reliable low risk process to build up the wall on such a complex casting?

The frames have been scabbed with welded on sheet metal by some prior shop. Is that the appropriate repair for the frame wear?

What side to side motion of the journal in the frame is acceptable in service?

We have a drawing of the journal on the axle and it shows the wheel side of the journal having a "fiber" disc, which I think is intended as a dust shield. What is an appropriate material for that shield.

This is my first post and I'm a machinist not a car/rail expert so any help will be appreciated.

Thanks.

Grant


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 Post subject: Re: Journal and frame wear on a Brill 21-E truck
PostPosted: Fri Mar 29, 2024 9:04 pm 

Joined: Wed Oct 13, 2004 12:56 am
Posts: 482
Location: Northern California
I would be interested to know what group, what museum, and what car this is for.

In a truck shop there are usually three sheet metal gauges used to build up wear in the journal box/pedestal area. One is a U shaped gauge that fits over the top of the journal box to check the width of the box where the pedestals run. This gauge also keeps the sides parallel. The next gauge is H shaped and it fits in between the pedestals. It controls the distance between the pedestals and the width of the pedestals, which goes between the gibs on the journal box. The third gauge is a rectangular gauge which controls the distance between the gibs on the journal box. The proper total clearance between the sides of the journal box and the pedestals is 1/8”. This controls free movement in the longitudinal direction. The total clearance between gibs and edges of the pedestals is 3/8”. This controls free movement in the lateral direction and allows the journal bearing to stay tight on the journal as the axle is oscillating up and down so the wheels stay in contact with the rail at low joints.

To make repairs, the first thing to do is verify the materials used in truck construction. There are a lot of cast iron journal boxes from this era. The pedestals could also be cast iron. The truck side frame is probably steel, but it could also be wrought iron. Welding on these parts will only be successful if the parts are steel. On steel journal boxes that have the sides worn so thin that pad welding is not practical, can have the sides cut out and new sides welded in. The sheet metal you saw welded in may have been hardened steel wear plates. Wear plates work best if there was room left for them in the original design. If the pedestals are separate parts bolted on to the side frame, it is best not to unbolt them, but just weld up the worn places in place. The bolts attaching the pedestals to the side frames are probably tapered or fitted bolts. Tapered or fitted bolts take special knowledge and experience to reinstall properly.

For a journal dust guard, most today are made of plywood. For a tight fit, make a large sheet rubber washer from neoprene and staple it in place. Dust guards can cause significant wear on the axle, so evaluate how much of a dust problem you really have.

When making new bearings, if the bearing is to be babbitt, the base material should confirm to the AAR standards for journal brass. For the axle bearings that clamp into the traction motor, high lead bronze should be used. Something like 932 or 936. A lot of bearings today are machined out of spun cast bronze. This keeps sand out of the bearing material and puts the casting of lead into the hands of companies that know how to deal with it. On the traction motor hanger bearings, new clearance should be 0.015”. This because the axle is fairly flexible and the traction motor case is rigid.

Good luck and please let us know how things turn out.


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 Post subject: Re: Journal and frame wear on a Brill 21-E truck
PostPosted: Sat Mar 30, 2024 12:31 am 

Joined: Fri Mar 14, 2014 11:44 pm
Posts: 201
toolmeister wrote:
I'm assisting in the restoration of a Brill circa 1913 streetcar. We are making new axle bearings (thrust plate and radial bronze + Babbitt) and traction motor (GE) bearings.


Some terminology to make sure we are all talking about the same thing.

The rectangular bronze bearings with the bottom side curved to fit the journal at the end of the axle is a "journal bearing." The split flanged bearings used to support the motor on the axle are the "motor-axle bearings" or "motor suspension bearings." These are normally not babbit-lined. The last set of bearings are internal to the traction motor, and are called "armature bearings." It doesn't sound like these are being touched.

I agree with Dave Johnston's advice. 15 thousandths clearance in the motor-axle bearings is 3 thousandths per inch of bearing diameter assuming a 5" motor axle bearing seat. That's typical of 40-50 HP motors like GE80, WH101, etc. The author didn't state what motors are involved. Smaller motors might have a 4.5" or even smaller seat if the axle was turned down. Another thing to check for is taper-worn bearing seats. Measure the axle journal OD at three different places and go off the largest measurement. Ideally the axle would be remachined straight but often that doesn't happen.

Another concern would be the OD of the axle bearings vs the ID of the bearing housing and cap. Again in a perfect world the two bearing housings would be line bored while assembled with a few shims, and the bearings machined to that ID so that removal of one shim will make them tight. With worn stuff, often some creativity is needed to shim between the bearing OD and the housing. With the bearings clamped in the housing, they must be tight. Strike the end of the bearings with a 2 lb hammer and a block of hardwood in between, they should not slide in the housing.

Also check dowel pins and dowel holes for wear.

Are you sure 3/8" total clearance in the side-to-side direction between the journal boxes and the pedestals, for street railway equipment?


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 Post subject: Re: Journal and frame wear on a Brill 21-E truck
PostPosted: Mon Apr 01, 2024 8:32 pm 

Joined: Fri Aug 20, 2010 8:25 pm
Posts: 490
If those journal boxes are cast iron you can built them back up with flame brazing. Clean everything with very stiff wire wheels and grind out any cracks. Heat things to orange/cherry red and deposit layers of brazing rod with flux.

You may need a wall of fire brick around things to keep the heat inside. Once done wrap with a welding blanket and let it cool slowly. After than you can easily machine the surfaces down to the desired position with a milling machine.

The brazing rod is actually about as strong as the original cast iron. If done properly the rebuilt material will last a long time.

This can also be done with "TIG Brazing", but I think the thermal stresses are larger with TIG brazing and more residual stress is left in the repaired area (my opinion).

Avoid the use of "Nickel Rod" or other arc welding on cast iron, it gets the cast iron too hot and changes the chemical composition. After the welding the cast iron and filler metal will become very hard and you will not be able to machine it.

If the journal boxes and/or frames are steel you can use arc welding techniques to build things up, but machining may be difficult depending on the original steel and filler rod composition. If the metal is "hard" and the weld filler is "soft" a cutting tool in a milling machine tends to "walk" around and/or "dig in".

If the frames are wrought iron you are on your own.... Only practical way to repair wrought iron is blacksmith hammer welding.... Very tricky.


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 Post subject: Re: Journal and frame wear on a Brill 21-E truck
PostPosted: Tue Apr 02, 2024 9:00 am 

Joined: Thu May 24, 2012 1:37 pm
Posts: 2300
If you can access the equipment, I believe some of the methods of metalspraying might work.

And consider dry-ice blasting to prepare the surface for the added material. (That would apply to brazing too.)

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R.M.Ellsworth


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 Post subject: Re: Journal and frame wear on a Brill 21-E truck
PostPosted: Tue Apr 02, 2024 7:45 pm 

Joined: Fri Aug 20, 2010 8:25 pm
Posts: 490
Quote:
I believe some of the methods of metalspraying might work


Yup, metal spraying will absolutely work, more expensive tools and materials.

Flame brazing can be done with an old fashioned Oxy/Acy welding or cutting torch with regular flux coated brazing rods. $250+ versus metal spraying kit $2500+

There is a gentleman on "youse tube" named Keith Rucker that shows many flame brazing repairs of cast iron castings and steel shafts etc. Worth watching.

Of course there are other folks showing metalspraying repairs as well.

Good Luck


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