HO Shay - replaced drivetrain and now the trucks derail?

[mkbradley]

 I have 3 Bachmann HO Shays that developed the usual cracked gears in the drivetrain.  That is not the what the question is. I accept that I need to periodically replace the gears.  I thought that buying the replacement driveline sets from Bachmann and replacing the broken ones would be an easy fix. It was easy to do.  However, now I am plagued with front and rear truck derailments.  Has anyone else had this problem?  Any solutions?

The parts I am talking about:

http://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=66_68_92&products_id=1651

Thanks,

Marty

[electrical whiz kid]

I can offer you some things to look at:
Crud in the lube (check the gears and the enclosure; a small speck can drive you bonkers).

Mis-alignment of shafts, binds in the movement.  Best way to see this is to set unit on a set of roller blocks, using a really bright light, and an optivisor (equiv.)

The ususal stuff:  bent or out of line wheels, bevel gears, etc)

Not any expert on shays or any other locomotives; but have had a fair amount of troubleshooting exposure to machinery.  Where I have been tells me to look for the little stuff; rarely will there be any kind of "exotic" problem-just the common garden-variety stuff.  Good luck.

Rich C.

[WoundedBear]

If one is not careful reassembling the Shay, it is possible that the truck frame catches on the coupler pocket..... both front and rear. Make sure this area is free.

Maybe check that the trucks are properly seated over their mounting pins before the screws go in. Make sure the trucks are free to swivel. Check that the pick-up boards under the mounts aren't bent up.

Is the truck frame still true and square after reassembly with the new side frames? Set each truck on a piece of glass to check that all 4 wheels touch. Loosen screws and adjust frame as needed.

Hope this helps a bit.

Sid

[mkbradley]

I remember back when Bachmann sold the complete trucks and had a successful replacement about 5 years ago.  Lousy success with the driveline replacements.

I did take a light file to the male parts to catch any burrs and some of the paint comes off, but it did not help.  Yesterday I took a light file to the female parts.  This may have actually made it worse. As the shafts extend out they may twist and bind under load???


I did check for contact with the coupler pockets.  I checked for bent or uneven brass contacts. I did not keep the truck screw too tight. I tried loosening the screws that hold the side of the trucks together.  I changed the gauge from a little narrow to a little wide.

I'm about ready to give up and retire 2 of my 3 Bachmann Shays, and hope the remaining one does not split any gears. Any other ideas?

[electrical whiz kid]

ok:  ask yourself these questions:

Did it work before you took it apart?

Did it work well (EG) same problems?...

I would not have altered the parts with a file for two reasons:  You have now voided any warrantee, and when you alter the shapes, you have now changed the dimensions-that the factory found to work, possibly exacerbating existing problems. 
If you do not know what you are doing, I suggest contacting Bachmann to see what you could work out with them.

[WoundedBear]

My solution has been to use NWSL gears and be done with the splitting problems, but if you're having trouble just replacing drivelines, then the gear route is probably going to be too difficult for you. I agree with what Rich said as well.....no need for files.

I don't know what else to suggest, other than patience and perseverance. I have repaired at least a dozen Shays and all have run great afterwards. Go back and start over......double and triple checking every step.

Sid

[mkbradley]

Many valid points.  I still would like to hear from someone that has actually installed the Bachmann replacement drivelines and either has had problems or has not.  I don't think anyone that has posted has installed the driveline parts.

I have installed some of the NWSL gears on one loco years ago, but if I have messed up the trucks somehow in this mess, that will not solve the problem either.

Thanks,
Marty

[WoundedBear]

I have used the drivelines. I have used complete trucks and I have used NWSL gears. I don't know what else to tell you. I can get them back together and make them run.

Sid

[RAM]

one thing that was not asked that might help.  Where does it derail?

[mkbradley]

Sid/Wounded Bear,
Glad you have had success with the driveline replacements as it gives me hope.

My latest theory is that it had to be multiple issues, so I was unable to isolate to a single problem.  I agree that any filing, even lightly to take off unseen burrs is a bad idea. I have been able to get one of the Shays to work OK (fingers crossed as I test for a few days) by going back to the untrimmed & unfiled shafts.  Additionally, I found one truck that seemed to have an axle that seemed to be a little off (the shaft sticking past the wheel seemed to be slightly longer than the other axle). The 2nd Shay is hopeless as all I have left are driveline shafts that I filed off the paint on the end.  So, I'm going to by another driveline set and see if I can get the 2nd Shay working.

I will note that I have a 3rd Shay that has been working fine the whole time and I have swapped trucks for testing and it is clear it is the trucks that are the problem and not the Shays.

RAM,
As to derailments, they occur on 18" radius curves over small vertical kinks at track joints, generally under heavy load (4-5 cars on 4-6 percent grades).  So, the idea of the driveline joints binding up (with a partial rotation) as they get close to pulling apart seems likely.

[ebtnut]

You might take a close look at the "vertical kinks".  They can cause all manner of woes.  Try and get all your track joints even, and if using EZ Track, make sure the rail joiners are all property inserted.

[DAVE2744]

Marty - I have the same model Shay, and have replaced driveline kits several times.  One thing I have not seen mentioned is the "neoprene" like universal ring(s).  These are where all the action takes place as the trucks swivel.  They are extremely delicate.  It is very easy to have one of the pins on a u joint slip out of it's hole in the ring.  This can be very difficult to see.  Even harder is to get it back into the hole, and stay there.  If this condition exists. the Shay will perform fine on straight track, and even OK on some curves.  On other curves not so good.  This will also cause binding, and I have seen it lift a truck off the rail, without stopping the engine.  I have since replaced all the rings with new ones, which seen to be a little more firm and slightly beefed up.  Check it out.  Good Luck,  Dave

[mkbradley]

Thanks Dave.  I will get out the magnifying visor and take a look at the universal joints.  I don't have access to my trains today but will let you know when I get a chance if I find anything.