Hi all, I got some sad news, after a few hours of running my sunset PRR H10s, the decoder started acting up. Upon some diagnosis, the decoder was fine, and instead a driving wheelset was to blame.
One of the wheelsets seemed to have insulation that was wearing out. Using my continuity tester, when I placed one lead on the axle and the other on the insulated wheel tire, the multimeter would beep, signaling a short. This is after I removed the wheelset entirely from the engine/rods/chassis.
I read the resistance, and it showed it had a resistance of 10 ohms between the insulated wheel and the axle. I have since stripped the paint off and cleaned the wheel, thinking maybe a piece of metallic dirt or something got in and bridged the gap, but it didn't help. Any thoughts on how to repair? Has anyone done insulation replacements?
I'd like to consider myself fairly experienced with loco repair, but this is definitely outside of my skill.
Charles
---------------------------------------------------------------------------------------------------------------
Modeling the PRR & NYC in HO
Youtube Channel: www.youtube.com/@trainman440
Instagram (where I share projects!): https://www.instagram.com/trainman440
Trainman440Any thoughts on how to repair?
I've fortunately never had to tackle such a job. I was lucky in the one case where I did have have high resistance between the tire and hub I was able to spot a tiny metal chip and managed to carefully remove it then "seal" the repair area with very thin ACC cement.
IF I were to make an attempt at the repair I believe I would approach it by removing the tire from the hub then make an accurate measurement of the thickness of the insulation. I have some models where you can see the bright red or white layer in there. Others use a darker brown color, no matter. It seems to be a type of rosin paper?
Once I have the thickness accurately measured I would then measure the thickness of my Kapton tape then determine exactly how many wraps around the hub it would require to build up to the same desired OD that the original insulation provided. I would leave enough width of the tape so I could slide the tire over the Kapton until it is almost in place. I would use Kapton that is 1/4 to 3/8 wide. this would give you some leeway when pressing the tire on.
Next I'd use a mini arbor press (drill press if necessary) and support the hub using a slotted piece of channel or some arrangement of full support. Then I'd find a tube of the nearly identical diameter of the tire to act as a "bushing" for the press arbor. You would want the bulk of the excess Kapton tape to slip just inside the pressing tube.
I used to press lots of bearing races in and out of gearboxes and I had gathered lots of various sized bushings. Sometimes, in a pinch, I could find a ratchet socket that would be just right.
Slowly press the tire in place until you have a nice flush fitting assembly. Now you can trim off the excess kapton tape from both faces.
Might be worth a try.
Good Luck, Ed
Charles.
I have had to replace drivers on some well used brass locomotives. Greenway products was my go to outlet. Sadly it seems that they fell to illness and the changing times. Sunset is still in business and it may be worthwhile to shoot them an email or phone call. A call to brass trains.com might be worth a try.
The repair suggested is worth a shot. Before pressing the tire back on the wheel you could put the wheel in the freezer and the tire in the oven on warm. Just be ready to install it. Any fumbling around and the expansion is gone. You may want to have a decent chamfer or rounded edge on the one side of the tire. A sharp edge could ruin the insulation.
Good luck.
Pete.
Years back I had an LMB NYC H10 with a driver short as you described. From an idea from Roy Brakmann (now deceased), I carefully applied ACC around the rim of affected tire and hit it with accelerator. It worked fine. No guarantee here...only what once worked for me. This was the only driver short I have had in the last 6 decades.
Luckily I've never faced this although I have pondered how I would get over the issue you are having. Where I personally would go would be along the lines of Howard's post but if that proved unfruitful I would clamp the wheel - somehow - with a vice and lightish pressure. I'd then remove say 1/5 of the insulation at a time (so that the relationship of the wheel centering to the tyre is maintained) then replace by masking whichever side was most likely to seal and fill the gap with canopy glue going in sections like that. This glue I'm sure you know is much more tenacious than it would seem. Once you have done this you should have a replacement insulating bond. Hopefully. Or go for a stronger adhesive.
Fingers crossed.
You got my curiosity up with this one. I've just looked closely at a Key insulated driver and unless the insulation is completely breaking down I just don't think it could be easily removed. So I would be keeping my fingers crossed for the thinned glue solution.
It may be easier to think about a repair if you found out how they were manufactured. Maybe Scott Mann at Sunset would give you some advice, or as others have said brasstrains.com.
The February 2020 issue of MR might be of help to you, look for "Miracle in Monterey: The restoration of G-D Line no. 10". Part of it explanes how Mr. Kenich Matsumoto created new insolation for the drivers because the original had melted after the fire that destroyed the Gorre & Daphetid.
I'm hoping Charles does a video on how he overcomes this, which I am confident he will.
Very easy but very time consuming. You dremel a small distance of the bad insulation out, fill it with epoxy and once cured, repeat till you have done the whole wheel.
I've had this problem a time or two. I used a brute force method that's a little scary, but works if done safely. You hook up leads to a car battery to the wheel that has been seperated from the chassis (if possible or at least take great care in order to get the electricity going just through the driver set in question.)
Then you briefly touch the leads to the battery.
The brief high amperage/low voltage current fries whatever is the trouble and your driver should be good.
Take care if doing this, but it avoids trying to reinsulate the driver.
Mike Lehman
Urbana, IL
I agree with Mike. I have done this several times.
What I did was first was took the tip of an X-acto knife and scraped where I thought the short was. Then applied track power to the driver using my 3 amp MRC 9500 power pack for several short bursts until I no longer had a short.
Thanks guys, I've never had that problem but it's good to know. By doing that are you creating a coat of corrosion that is not conductive?
Simon
mlehmanI used a brute force method that's a little scary, but works if done safely.
I watched an electrician at a B&O roundhouse use this method (with a welder rather than a battery) to find a short inside the myriad runs of conduit in the engine room of a F7 one time.
Yep. Found the short Blew the cover off a junction box. Would have taken days to track that down otherwise.
Thanks for the replies all! I never got to replying cause unforunately i dont currently have a source of power to try the burning method.
I contacted sunset and they also recommended taking a high amp power source ( they recommended a car battery) and trying to short out whatever's causing it.
In any case, once I do get a chance to try this repair out, I'll come back to this topic, but until then, I have the engine disassembled.
Cheers all!
Burning the short out may work if the cause is a small sliver of metal. If it is caused by the tire touching the driver center you may vaporize one or both of them, especially with the car battery.
As a former big truck and mining equipment mechanic of nearly fifty years. I must caution against using any lead acid or even a lipo battery that you will short. Number one all lipo and lead acid batteries expell an explosive gas. Any spark or extreme heat source can make it literally blow up in your face. Houses have been burned down because of shorted lipo batteries. I've seen and know mechanics blinded and permanently scared for life from battery explosions. Safety glasses will not protect your eyes when they are blown off your face.
Be safe and use a circuit breaker protected battery charger. A little ten amp buzz box should be more than enough and nothing will blow up in your face or burn down your house.
Thanks for the warnings...yea I have no idea if its a little wire dust or if its the insulation that's degrading. This issue didn't exist previously, it kind of just occured out of the blue, which leads me to believe that its just some debris. Then again, I stripped the paint off the wheels and the short is still there...
Might try using one of those 3 amp power supplies as someone mentioned.
Okay, FINALLY an update. I fixed it!
I took the wheelset off the engine and pulled the wheel off the axle. The resistance still read only 5.5 ohms, which is very low, and indicates that likely applying high current to the wheel with a car battery or power pack (as mentioned above) will likely just destroy the wheel, as its not just some small metal dust or debris thats causing the short.
I was originally going to try and heat the tire to hopefully loosen it from the wheel but didnt want to burn up the original insulation and didnt really have the means to apply heat to precise parts. So I just started tapping away gently with a hammer. I placed the wheel flangeside down against my NWSL gear puller, where the tire was supported on the edge but the wheel wasent, and worked my way around, gently apply equal taps around the wheel till it fell out. Due to the uneven surface of the wheel (the counterweight and the screw hole for the crankpin were all at differing heights), I had to gently go around the wheel so to not push it out unevenly.
The wheel actually came out rather easy, the press fit was much looser than the wheel to axle fit. After inspecting the insulation, I noticed that it was in really good condition still. I was baffled at what failed, till i noticed the lip around the tire, and suspected that the lip (Which covers/bypasses the insulation) somehow touched the wheel. So my next steps were to trim down the lip, which was done with a dremel stone wheel placed in a drill to SLOWLY grind down the lip.
After cleaning up the tire and removing all traces of brass dust/shavings, I repressed the wheel back onto the tire by tapping with the hammer again, going very slowly, and giving equal taps evenly throughout the wheel to make sure it goes back in straight.
And that's it! A final test with the multimeter shows zero continuity between wheel and tire. You can see in this final image how the lip on the tire goes OVER the red insulation (which cant be seen since its under the lip), and can easily touch the wheel itself, and how trimming the lip can prevent a short. Also note that previously, the lip of the tire was basically touching the counterweight on the right, whereas now theres a decent gap.
I didnt seat the wheel all the way in to also prevent the tire lip from coming in contact with the wheel. I pressed the wheel back on the axle and now its all ready for paint and reinstallation!
I think IF the insulation WAS broken, I would have done with Ed said and wrapped kapton tape around the wheel until the same diameter was achieved...diameter can be measured with calipers. Then pressed the wheel on and if it was still slightly loose I could use some glue to prevent the tire from slipping on the wheel.
Anyways, hopefully this helps someone out there, whos in a similar unfortunate circumstance of owning an engine with a shorted out wheel.
Cheers,
Nice tutorial, thanks for the class on 'how to'.
Good job Charles.
I haven't had the shorting issue. But I do have some worn out drivers. It appears that Greenway products is open again and taking orders for April deliveries. They are my go to place for drivers.
Apparently this happens only once every 60 years... Well it just happened to me. Bought an old CP 4-6-0 a few weeks ago. Worked fine on DC at the hobby shop. Installed DCC and yup, realized there were intermittent shorts coming from one driver. This old thread helped me fix it.
A trick I can add here is that I was able to remove the shoe by putting the wheel on my vise, and tapping on it gently in the centre with a piece of wood :
IMG_20241204_161523 , on Flickr
The shoe slid right off. I then did the same procedure to remove the offending particle presented by Charles. The engine now works fine.
Thank you dear colleagues!