AF diesel die cast axle bushing replacement

imageI just got the bushing replacement tool to replace or to install axle bushing into worn out die cast diesel trucks. I am looking for a unit that has egg shaped axle bushings to repair. No charge, just want to use this new tool. I have been doing repairs for several shops over the past 20 years in my geographic area. I have been dealing with Jeff Kane for parts for over 20 years.  Please let me know if you have a candidate. 

Attachments

Photos (1)
Original Post

Here hopefully is a picture of the jig that I use for re-bushing my diesel chassis.

The chassis is locked into the jig so that it can't move. I have a selection of slip bushes which are used in the jig to insert an 8mm oilite bearing and then take out the corresponding side to accept the stepped axle journals.

I have done quite a few chassis and never had a failure so far.

Attachments

Photos (1)

Here are a few tips that may be of help when you strip down a chassis that I have learnt over the years.

Try to only pull off two wheels on one side, the side that has the solid wheel with an insulator that fits on the axle, the other wheel being the PM wheel will also have an insulator. Reason for this is that if you pull the solid wheels from the axle they don't always go back on with a tight fit. 

The axles depending on how worn they are can cause problems with the new bearings and they will wear out prematurely. They tend to suffer more from electrical wear than mechanical as the current goes through them to get to the chassis and this causes pitting, even with the sliding pickups. At this point it is best to change them for new ones if you can still find them. I have quite a few for when I need to use them but then a number of these are not perfect either. I have seen on the larger journal what looks like a scratch line on the full width which I can only presume is where the cutting tool used to machine them has been pulled back once it has finished the job. You can feel it with your fingernail and if used as is will again chew up a new bearing as it acts as a cutting tool itself.

On reasembly I also add some shim washers either side to reduce excessive side play on the axle/wheel assembly, this helps to keep the axle gear centralised in the middle under the worm.

 

This is is what happens to gears when the chassis axle hole becomes excessively worn. The two gears on the left came from a 372 GP7 which I picked up many years ago. 

The gear on the left shows that it had been meshing right up into the worm, which over time has worn the teeth to point and reduced the height compared to a new gear on the right. Also the left gear leaning to the right indicates it was not centred under the worm fully. The middle gear also leans slightly to the right but was not far from the centre. 

A chassis in this condition will give poor performance, runs slower which means it will be pulling more current which further compounds the problem. You also run the risk of possibly burning out the armature if left like this from extended running.

In some respect the diesel chassis was not one of Gilbert's finest bits of engineering, to be honest they can be a PITA to get running well at times.

 

IMG_0207

Attachments

Photos (1)

Hello STEW1957,

A couple more pictures to show how a well worn chassis can look. Your one actually doesn't look too bad considering but will give you some good practice on rebuilding these chassis.

A new axle measures 4.55mm for the large journal and 4.09mm for the small journal on my micrometer if you need some reference data.

On the bottom picture the large journal hole measured top to bottom at 5.12mm and 5.55mm left to right.

Before you start to reassemble it back again let us know how it goes and I'll go through how I cleaned up the axles to remove as much scoring as possible before I got a supply of new axles, it isn't what I would call good engineering practice but then I had no other options back then and it did work.

Below is chassis showing small journal

IMG_0214

Below is the large journal hole, again seen better days.

IMG_0218

Attachments

Photos (2)

Hello STEW1957,

i just had another look at your chassis and I can't quite work out which one it is but I think you may have an early chassis with a part number of PA11412, if it is then it will probably have the early steel bearings that can be knocked out, replacements for these can be purchased from SNS, who also specialise in rebuilds.

The chassis you need which is the more difficult to rebuild is the PA12B065 which has the holes machined direct into the chassis.

Good eye UKAFLYER. It is a 11412 frame.  The frame appears to have two pressed fittings. The axle bushing, then a bushing for the axle bushing pressed into the frame. Is this correct?  Do you have the part number for the left and right axle bushing? I would prefer not to drill if simple rebushing can be done. 

I have done numerous bushing replacements on Lionel motors and frames. In the past several years I have repaired many PAs that are getting to the point where the slop is so bad it is starting to affect their operation. Thank you for your sharing.

 

Hi,

go to this link and contact them for availability of early knock out bushes. I have never seen ones with the steel bush inserted into another metal sleeve, normally all the ones I have done have the bush with key way inserted direct into the chassis. The new bushes at below are brass and do not have a key way, it isn't needed. There are no part numbers for these bushes.

http://snstrains.com/Services/rebushing_services.html

Thank you for the link. I wonder if this truck has been serviced with replacement bushing in the past. The axles are heavily scored so they will be replaced. From what you posted earlier damaged axles will quickly damage the new bushings. I have ordered several axles from Portlines Hobby.

So the frame PA12B065 has no bushings, the axle rotates directly on the casting?

Yes, the axle runs directly on the pot metal casting. The design did not take into consideration the electrical arcing that happens--it's not really "wear" that causes the problem! I have considered adding wire wipers on the back side of the wheels to reduce that arcing, but so far the design is only in my head! I've also considered making the new bushings a bit long, so they stick inside where the gear goes to provide a "centering devise" to keep the gear in line with the armature. I have yet to put these ideas into practice to see if the ideas are any good. With my present situation, I probably won't get around to testing the ideas for at least a year, so I provide them here to see if anyone else wants to give them a try.

S'incerely,

David "two rails" Dewey

This is what I had to resort to many years ago to clean up axles which were scored and looking a little worse for wear, not the best engineering practice but sometimes there is no alternative.

I had access to a small lathe and used to put the axle in without tightening too much to make a mess of the knurled end. I would then have strips of wet and dry at about the width of the journal at 1000, 1500 and 2000 grade. Start with the 1000 and keep it wet and just wrap it around one journal at a time to remove the high points. I would then do the same with the 1500 and 2000 grade until it was cleaned up and looking smooth. The best way I found how good it was is simply to run a finger nail over, it is surprising how sensitive it can be to find imperfections still. Also, just feeling it also can help. 

It isn't the proper way but when you don't have access to new ones it was better than nothing, perhaps a chapter of my repair days best forgotten.

I am still running a fair few of these and they are still holding up well.

The Hobby Horse bushing kit is not needed with the diesel truck 11412. The bushings in this truck press out easily. Port Lines Hobby sells the bushings as a set of four. The bushings come predrilled for the left or right side. 

Still looking for diesel truck PA 12B065 to use my tool. IMG_0013

Attachments

Photos (1)
MIlan, It's because of the knurling for the gear, it has to be larger than the bearing area in order for the gear to slide on. The knurling for the wheels must be smaller than the small diameter bearing area. So, there are actually 4 steps to the ACG diesel axle, as the large diameter bearing area gets turned down to the size of the wheel knurling. The later L production doesn't bother with any of this! It just has a looser fitting bushing (or they put the bushings on after the axle is pressed to the gear and in the chassis--I'll admit, I haven't had one apart to check that out.

S'incerely,

David "two rails" Dewey

The dimensions for the Lionel axles (new) are 4.05mm for both journals while the spline for the gear comes out at 4.30mm. The bushes bore is 4.15mm, 2mm thick and 7.90mm diameter. So it would seem that the gear was put on the axle in the chassis and the bushes then slipped over the axles and pushed into the chassis. The chassis thickness is not the same for each side, one side is 3.34mm and the other is 3.50mm, not that it makes any difference really.

I have rebuilt a few of mine and use the same bush that I use in the ACG chassis except I take out the bore to 4.10mm while the thickness of the bush is 4.00mm, twice that of the Lionel one. Another interesting fact is the measurement of a Lionel axle after it has been pitted by electrical arcing comes out at 4.10mm

Hop this helps if anyone is interested

Thanks UKAFlyer and others for the informative posts and photos on this always intriguing topic.  I especially appreciated the drive-gear photos showing how the worm wears right into them.  I have some photos of a PA 360 overhaul that I recently completed including bushing replacement, and a short video on that as well if you're interested.  Click here for the photos, and here for the video.  Thanks. 

I have re-bushed Lionel/AF diesel trucks.  Like the early postwar units, they're pretty straightforward.  In fact, years ago when I bought several Gilbert diesels, I removed their Gilbert trucks, set them aside, and replaced them with Lionel trucks so as to preserve the originals and have trucks in them with replaceable bushings.  

I too have the Hobby Horse tool set, but haven't bushed latter postwar diesel trucks yet.  I'm too impressed with the work of the master machinist that helps me with those.  But I look forward to giving it a try someday. 

Precision Flyer Repairs -- postwar and modern S-gauge train repairs and upgrades

Get it done with Precision

precisionflyerrepairs.com

David Horn

 

Hi SGAUGIAN!

like the photo's and the video, gives a good visual process for others to follow. The early ones are really within the realms of most people to do with basic tools.

The picture of my worn gears, especially the one on the left also caused the spherical bearing on the armature to wear badly and I changed it as well. It is the only time I have seen an armature bearing bad enough to change.

Thanks UKAFlyer.  That's interesting.  I've had several that required armature bearing replacements.  Always done as a pair of course.  Never just one or the other.  Click here for a quick video about three AF Alco PA's recently revived.  Each with their own story as they always do -- one required the bushing of both trucks, one no major truck work, but needed it's reverse unit overhauled, and the other didn't require bushing, but did require new armature bearings.  Subscribe to my YouTube channel if you'd like to know when I post new material.  Thanks. 

Precision Flyer Repairs -- postwar and modern S-gauge train repairs and upgrades

Get it done with Precision

precisionflyerrepairs.com

David Horn

 

Whenever I am going to run a diesel that has been stored for a while I always give it a light overhaul which includes a lubrication. It is possible that a lot of people will lube the axles and put some grease on the gear but the two items that seem to get neglected are the bearings on the armature. Although they are olite bearings I still give them a small drop of oil,  maybe this why I don't have any problems with them. I use a syringe with a fine needle that has the pointy bit on the end ground off and this gets right onto the armature shaft next to the bearings.

I do the same thing and agree.  Most people don't even know those bearings exist.  After I'm sure they are free-spinning, I use a needle-oiler to get a drop of LaBelle 107 on each of them.  The wicks were supposed to help keep them "wetted", but usually I find those are either bone dry like the bearings or plugged up with old lubricant of some kind.  Soaking them in solvent and wicking them dry into a clean cloth or paper towel revives some of them, but not all.  On the other hand, I've had diesel motors that are completely seized because some one years ago greased them and the old grease hardened to the point you can't even turn the armature on its bearings after removing it from the truck.  Not until that petrified layer between the bearing and armature shaft is removed is there any movement.   Doesn't hurt also to ensure the pressure plates are present, in good condition, properly positioned, and given dab of grease as well.   I use a larger syringe to inject/apply Lubriplate 630-AA.   Rather than just glob grease into the gear bay and pray, after making sure the parts are all degreased, clean, and dry, I like to inject grease into each groove of the worm, every tooth of the drive gear, and around each axle bearing and then while slowly running the motor in both directions see that it adheres to all the proper surfaces.

Precision Flyer Repairs -- postwar and modern S-gauge train repairs and upgrades

Get it done with Precision

precisionflyerrepairs.com

David Horn

 

It looks like we both have the same approach to maintaining these chassis for longevity. I've also seen the armature bearings 'glued' to the shaft and slowly coaxed them back to life again. 

For a long time now the first job I do when I purchase a diesel is to pull it apart. It just isn't worth trying to run it as there is probably going to be something wrong somewhere with it and as you mentioned the oil has probably dried out and the grease hardened.

The pads that limit the armature end float seem to be made of fibre and I would be interested to know if metal (brass) ones are available which would last longer.

Nice video Dave, thank you for sharing. One thing in the video I did not see is how you deal with the field alignment adjustment with the set screws. For me it is trail and error until the sweet spot is found. Could you elaborate on this procedure? 

Thanks!

Stew,

Good question.  It is pretty much as you put it, trial and error, but here are few thoughts about the approach I take in case that helps.   After doing so many, I've never really thought about the process or procedure I follow, but before removing or unscrewing anything with regard to the field, yoke, or centering screws I observe the relative positioning of everything to begin with.  Do the armature winding segments look centered in the field?  Does the armature spin freely by hand in both directions and no segment make contact with the field?  Are the field laminations vertically aligned with the edges of the yoke, or parallel to the yoke?  Is there a reasonable number of laminations ahead of the field as well as to the rear of it?  Are the number of laminations fore and aft of the field equal on both sides of the yoke?   Those are desired state attributes.  How balanced do the centering screws look in terms of how much one is screwed in compared to the other?  If the engine is operational, how balanced does it run in forward compared to reverse?  Basically capture either in your mind and/or photos the existing state, before you disassemble it.  Assuming complete disassembly was required, then upon reassembly, before installing the armature and field, I hold the field in the truck to see if it fits well into the truck -- any obstruction, casting seams, etc. in the way?  Can I get it to stand perpendicular when looked at from the ends as well as from the sides of the truck?  If you can't at this point, it won't when under the centering yoke and screws.  Then once the armature and field are on the truck and the yoke slipped over the field (with both centering screws backed out), reattach the yoke to the truck.  Make sure the armature is properly seated -- some longitudinal play end-to-end against the thrust plates, free spin, etc., plus of course armature bearings that are not worn out among other things you would have inspected previously while disassembled.  Lastly work on centering the field on the armature.  I hold the field in as close to the optimal position as possible, screw in one or the other centering screws until it just touches the field, then do the same with the opposite side screw, then turn the first screw an 1/8 of a turn, do the same on the second screw, and repeat that until both screws are snug (do not over tighten).  With any luck the centering held and things look, spin, and run well.  If not, try backing off one screw and tightening the other by as much until you get the desired result you want -- that can sometimes be the trial and error part of it.  After all, these were manufactured as toy trains, not scientific instrumentation or precision time pieces.  Hope that helps.

Dave  

Precision Flyer Repairs -- postwar and modern S-gauge train repairs and upgrades

Get it done with Precision

precisionflyerrepairs.com

David Horn

 

IMG_0015IMG_0016IMG_0017Got the truck completed. Secured the bushing to the frame with CA at the 9 and 3 O'clock position. Axle through the gear, press on the wheels. This job was easy to accomplish. Fore and aft slop of the armature mesh to the gear is gone. Very satisfying task. Still looking for a worn truck without bushings to use my tool on.

thank you guys for the advice!

Attachments

Photos (3)

Stew1957, what I would like to see is how that tool you showed is used to replace bushings.  A few years ago I started replacing bushings. Also tried my hand at adding bushings to the later motor truck. Failed once or twice but got one working ok. Gave it upfor I was working in the dark, thank you for posting your tool and the repair of bushings in these Alco diesel trucks.

Add Reply

Likes (1)
C W Burfle


OGR Publishing, Inc.
33 Sheridan Road, Poland, OH 44514
330-757-3020

www.ogaugerr.com
×
×
×
×
×