American Models Split Gears

I wonder if it's a flaw in the gear material, or  expansion due to temperature changes that cause this.

I also can't help but imagine your carpeting looks like a pizza that you laid SHS track down on. Maybe it's just the lighting, but now I'm hungry. 

Nice documentation of the repair. This was thought out in advance and organized. When I had one of my AM diesel trucks apart finessing the square bearings back in was the most time consuming. It looks like the cracks could be from material shrinkage after the gears were press fit on the axles. So far I have not seen this failure but if I hear squealing I now know where to look first.

I have recently  been hearing occasional reports about split gears on both AM ans SHS products.  It doesn't sound like an epidemic, but it has been happening elsewhere.  Northwest Short Line has a replacement gear for the SHS 2-8-0's that someone commissioned.

The interesting thing is my Scale U25B's have a lot more "mileage" under their wheels than the HiRail units.  Maybe just the luck of the draw.

Rusty

I was told by a chemist that " pure delrin " does not shrink. They cheat on making the Delrin & this shrinkage is the result. ( split gears ) I had this happen several years ago on a SD 60. Mind was running but making a " whap-whap " sound.

 Bob Guckian

"Mind was ... making a 'whap-whap' sound."

My mind makes a whap-whap sound occasionally, too.  Happens when I try to remember someone's name at a party.

I'm sorry to see this for you. It happens in G scale also. I found a set of K line trucks that I took from their GP and installed NWSL delrin gears into it. So far, it has performed perfectly. I may look for more someday.

 I also put a set into a USA trains GP engine. I never finished upgrading that engine to test it yet.

those gears are junk someone should make them out of brass.  I worked on a engine for a friend of mine same problem.  am stuff is junk!!!!!!!!!!!!!

kenv posted:

those gears are junk someone should make them out of brass.  I worked on a engine for a friend of mine same problem.  am stuff is junk!!!!!!!!!!!!!

Thank you for adding your valuable insight to this issue...

In 30 years, this is the ONE and ONLY major problem I've had with an AM locomotive and I have quite a few of them in both Scale and HiRail, to say nothing about my fleet of freight and passenger cars.

I'll still recommend AM products to anyone entering S.

Rusty

I've had two American Models gears split. But then I've bought 20 of their locomotives in the last 30 years, and they have been extremely dependable. One of the great features is that it's easy to buy replacement parts and install them yourself, something that can't be said for brand new products from some other manufacturers who deliver almost a year after an announcement, supply defective products when they finally do arrive, and have no repair parts in inventory for just delivered product.  When American Models announces a product, it's available within a few months. It works right out of the box, and it works for years. If it ever does break, Ron has the parts and the suggestions for a fix.

It seems our friend has supplied the same insightful comment to a thread on the 3-rail side.  Our man of singular opinion may be a sleeper troll.

Rusty

I'm curious if anyone who has had this problem tried to contact Ron at American Models to see if replacement gears are available and if they would be provided gratis?  If the gears were defective I would think he would be accommodating.  He seems to be a reasonable guy to deal with when problems come up with his products.

It seems to me to be a very expensive fix to replace all the wheelsets rather than just pressing on new gears.  Of course I have zero experience doing either so it may be more involved than it seems. I have a fair number of AM engines but since I only have a test loop of track I doubt any have more than an hour run time on them.  Someday I expect to have a layout, and I suspect I could have this problem in the future.  If AM does not have just the gears available, I would be interested if anyone has a source of such.  I’d like to have some on hand for future repairs.

 Dean Hall

The locomotive wheelsets with gears run from $6 to $7. Trying to pull off a wheel, force on a plastic gear without breaking it, and then replacing the removed wheel with the precise gauging of the original seemed to be far more effort than just buying the entire wheel/gear set. Replacing the set is a very simple matter but does take some patience because the bearings rotate around the axles and, like frisky 2-year-old kids, refuse to go where they're told. I broke off the defective plastic gear on the bad axle and saved it for future projects.

I have bought American Models parts for detailing, upgrading, and repairing my own mistakes over 30 years. They have always had the parts available; and I suspect that for drive-train parts such as wheels, wipers, motors, and gears they keep an ample stock. These parts are common to multiple AM locomotives, which makes parts management simpler and keeps costs down.

It cost me around 42 bucks to do both locomotives.  I could have cut that cost in half by just replacing the 4 wheelsets with the broken gears, but why take the chance?

The U25B's were released 2004 and they would be out of any reasonable warranty period anyway.

A solution would be to send a gear off to North West Short Line and have them cut some new gears for replacements, (Someone did this for the SHS 2-8-0, replacements are $14.00 each) but then there's removing the wheels, removing the gear, installing the new gear and regauging the wheelsets.

My scale wheel Burlington U25B's haven't exhibited this problem, and they have much more run time than my HiRail New Haven's have.

Rusty

OK, at only $6-7 each I'm with you. Far easier to just replace them then try to press on new gears. At that price I think I will review my inventory of AM diesels and order some just to have on hand.

Dean