split USA axle gears

[enginear joe]

 Paul Norton posted a fix on another site for the USA axle splits that occur. I'm trying it out using the K&S metric brass tube that seems just a hair too loose. I tightened it by running the cutter around the tube pieces just enough to indent it and make some ribs. I'm swapping out the wheels with larger NWSL ones.

[Rayman4449]

Interesting idea Joe, thanks for sharing  Would like to know how it holds up long term.  My original thought when I considered this myself was that any piece of plastic like the axle sleeve, etc that was still under force/pressure would continue to see it's crack grow and or might end up seeing the split pieces break off completely over time.  But it may not end up being like that and could hold just fine.  Do the wheels hold really tight in the axle sleeve without spinning when force is applied? (so that the axle sleeve just doesn't spin on the axle end)  I have a whole box of split USA gears with axles that I may experiment with some.

[enginear joe]

I think the best thing about this fix is that it traps the split so that the pieces shouldn't let go down the road. You can adjust the tightness of the brass sleeve by the depth of the ribs that the cutter made. It seemed like the NWSL axle were just a hair thinner. The ribs are also smaller so re-using a used, split gear, probably made the job just a bit tougher. I added glue to help keep things tight.

 The price of the fix made sense to me. I bought new wheels and gears for my SD70MACs and it would have broke the bank to swap all the rest of my engines.

[Rayman4449]

Really good idea to add some glue, i mean really you have nothing to lose.  Nice work!  Yes this is something I find frustrating that the gears on these particular engines (not all USA Trains engines) have this known problem with the design and what appears to be plastic type yet it's not ever redesigned or done with a different type of plastic to try and eliminate the problem.  The 3 axle engines have main gears with what seem to use a different type of plastic that doesn't split (from what I've seen).  I mean it can be done.  At least NWSL sells replacement gears made out of delrin plastic that if you really want to fix the problem you can buy those.  Keep us posted how this works out.

[enginear joe]

I bought the NWSL delrin gears for the K-Line engines. It seemed like a good solution and they even seem slightly flexible as the axles were inserted. These were much cheaper than the USA version? $10 something versus 25! I'm interested in how they hold up to wear also. At least the USA axle gears I'm looking at, don't show much wear. I had some idlers that were stripped.

 It was Paul's idea also to add the glue. I used Gorilla brand super glue, as it's tougher.

[Rayman4449]

Idlers, so you had some idler gears in the USA three axle blocks that were stripping?

[enginear joe]

 Yes, the idlers were severely  worn and allowing the wheels to slip.

I was told that USA changed the splines first on the axles. They also changed the plastic in later versions, I was told.

[Rayman4449]

Interesting on the worn/stripped idlers.

 

Well maybe they did change the plastic but from what I was seeing on all the replacement axles that was ordered they didn't appear to have a different look or feel.  Also, the plastic still looked different than the main gear/axle used on the three axle engines. (Which is what I kinda would expect they would go to since the 3 axle engine axle gears seem to hold up good and not crack)

[Chuck]

I've tried that "fix" on numerous USA loco's and to be quite frank about it I wasn't impressed. Since the plastic can't expand when the axle is pressed back it has to shear the id of the hole. Usually that shearing effect happens only to one side which ends up throwing the whole axle/ wheel assembly off center which makes for bobbing or swaying from side to side drive block.

 

Yes it works and will "fix" a cracked gear assembly but IMHO it's only a temporary fix until the proper replacement parts can be obtained. If the gears are in new loco's then USA will send replacement parts for free. If buying from the used market then just have to figure on replacing the gears and add it onto the purchase price.

 

USA is well aware of the problem but just like any other problem with there products they ignore it. I quit buying USA Trains because of this. When the S4 was introduced USA Trains held off shipping them until all the drives were checked and any or all gears replaced.

 

All USA would have to do is change the way the gears are made. Instead of using cheap injection molded gears use machinable engineering grade plastic and machine the gears. Or re-design the drives and use metal gears. Insulate the wheels from the axle then use all metal gears but that would screw up the electric flow from the axles to the side frames. In other words USA Trains has a crappy drive block design period and it seems that Chucky refuses to acknowledge it. As long as he's making a ton of $$$ by selling replacement parts at extortion prices he's happy..good for him.

 

Like Mike Wolf of MTH said years ago.."Why use cheap plastic gears when metal ones only cost a few cents more?" (at the manufacturing level). 

[enginear joe]

 Trust me, I'm not happy overall with this. I spent a ton of cash on their parts already. It seems like a reasonable fix and I'll see how it holds up. If the axle installation was that bad, I bet U could install the brass sleeve loosely against the wheel, and then push it on the axle gear afterwards? With the NWSL axles being looser, it's not a concern to me right yet. I'll have to see if I guessed right on the amount of tension the brass sleeve is putting on the setup.

 Guys were using fishing line wrapped around as a fix.

[enginear joe]

  I swapped out the smaller stock wheels to larger 40" on my GP38. I haven't attached the brake shoes back onto the side frames yet. I'm not sure it's worth the hastle to me.

stock on top

 

[markoles]

I've got an old F3 that is currently in kit-form.  I suppose if I really wanted to, I could check it out to see if I have the axle problems.  What do I need to do to check? 

[Rayman4449]

Flip the engine over and remove the bottom plate on each motorblock.  pull each axle and physically look for splitting down the side of the sleeve where the axle inserts into the gear.  Could also try and twist the wheels in your hands but if you dont have splitting they shouldnt spin.

[enginear joe]

 My K-Line engine was split so bad, not only would the wheels turn easily, they also lost the correct spacing and would derail itself! It wouldn't even go forward well as the wheels weren't turning smoothly. The seller said that it ran good???

[Chuck]

I have lots of 20 year old Lionel Large Scale locomotives and 2 in particular have many hours of run time. Upon inspection of the drives after a thorough cleaning the white plastic drive gears that are pressed on the axles look brand new! No cracks or stripped teeth...just some very slight normal wear. If Lionel can do it then Ro can to.

[enginear joe]

 I bet that's where years of train building experience trumps all.

[Chuck]

Well Ro has been at it for 20 years now but seems to refuse any change in design? 

 

What I thought was really funny is about 10 years ago when Aristo announced the "new & improved" prime mover gearbox that was "engineered from the ground up"....thing is it's a direct copy of the high end O Scale brass engine modular gearbox design that goes back to the 50's?? Only mistake is that Aristo made everything out of plastic which doesn't last...worm gear internal hexes that strip out and axles made out of brass which wear out...axles that mount onto plastic spur gears by 3 teeny tiny screws...junk.

 

MTH is all metal drives...best in the business!

[enginear joe]

here's some pic's of the idlers in my SD40-2. I don't have pictures of the other stripped idlers in my MACs.

[Rayman4449]

Goodness Joe, those wheels don't look like they have that much wear on them!  The sliders look like they have almost NO wear!  The gears a still fully lubricated, how in the world could they get like this??  Are those new sliders?  Were those axles with gears replaced at some point?  ALL the Mfgs need to go with all metal gears.  I know Accucraft uses metal gears in their electric steamers, and I'm betting if the do produce a diesel (GP60) they will on those too.  USA Trains uses metal gears (massive metal gears) in their steamers (but obviously not diesels), MTH uses all metal gears in all their engines.  With Aristo gone of the mainline US mfgs that just leaves USA as the only one still using plastic gears.  (Bachmann and the others use plastic gears but they don't make the mainline engines like SD70s, Dash8/9 etc)  Given how bad the market still is there is probably little incentive for any kind of return on investment to even attempt this sort of design/mfg change, but I do wonder how much more it would actually cost for them to implement this change.  As Chuck mentioned Mike Wolf has apparently said at the mfg level it really doesn't cost that that much more.  I guess the only thing you can do is stock up on these parts for the future as if USA ever closes up shop you could find yourself in a bad situation.  I would keep a brand new example of each on hand that could be used to send to a company like NWSL to have them duplicate the gear assembly.  

[Jim Miller]

I believe the high end Bachmanns like K-27 and C-19 have metal gears...................Jim

[markoles]

I have been trying to think of how one could improve the aristo design by utilizing metal gears in that system.  I keep coming back to the problem of power pick up.  If that's eliminated through battery use, then there's no problem.  Except I'm not battery powered.

 

The aristo design uses metal wheels and metal axles, with the heavy plastic for the gears.  I actually never had any of the gears strip under NORMAL operating conditions.  I did deform one gear when I was plowing 6-8 inches of heavy wet snow for a few hours and got ice built up that prevented the gearbox from sliding on the axle.   And that was serviced by me with gears aristo sent me free of charge, despite being a dummy and plowing with a toy locomotive. I never had an actual problem with the 3 small screws either. 

 

My perspective on all of these gearboxes is this :consider the age of the designs and what was happening around the time of the introduction.  The USA was an improvement over the LGB design, which was very similar (sliders and power pick ups on the wheels with brushes). It was also an improvement of the aristo B truck design, too.  Then, the Aristo gearbox got the makeover, and while not going all the way with metal gears, it was a vast improvement on the earlier USA and Aristo designs, and LGB too.  MTH was able to see all of those improvements before releasing their hudson in 2003-4.  I've not had any first hand experience with the latest Bachmann big hauler metaled gearboxed Annies, but I am tempted. 

 

I don't think any of the old USA design, LGB design, Aristo design, etc.. was 'stupid'.  They are natural progressions based on available engineering, materials, and resources (money).  Look at the history: Narrow gauge = short trains . As things evolved,  we, the users, demanded standard gauge models, and then we demanded they haul prototypical length trains.  I am as guilty as anyone, but the toy train moved in the direction of model, while still being an electric train, there's a lag.  And I believe the manufacturers chose to spend more money on the details of the model than what was going to move the model.  Let's forgive them for that motivation and move on.

[Rayman4449]

Excellent points.  I completely agree about the history and that this is part of a progression.  When you look at where the hobby/product was back when it first started to where we are now, there is big difference.  The positive side with the USA approach is the ease of gear replacement.  (Replacing a gear or gearbox in an Aristo block is a pain!)  It would seem the way to do this on the USA side would be to make the main axle gear assembly metal with plastic inserts inside where the axle ends fit into the gear.  Then from there you could replace everything with metal.  In fact, it could be possible to contract this out with NWSL to have them design and fabricate a replacement like this, not sure what the cost would be.  In the end it could be a worthwhile investment.  Does anyone know if NWSL does that sort of custom work and does anyone know what the general costs are?

 

On the Aristo side I've spent time thinking about it too and the only thing I can thing of is a similar approach for it as well but I think it would be more difficult.  The main problem would be to replicate the worm gear in metal and creating a receiver in the worm hex shaped to receive the motor shaft.  I'm not sure what good options exist to redesign the Aristo gearbox.  

[enginear joe]

 Ray, everything was stock and I've owned the engine since it was new. I swapped out the idlers and got rid of the rubber tired axles so there should be less wear down the road? I think USA started eliminating the rubber tires on newer releases? That might help.

[enginear joe]

 Yes, if you speck out what type of gear you're after to NWSL. There's a form on their site I believe.

I tried casting a gear out of better plastic and it came out quite well. It slips on the axle too easily so it needs some work. I wrecked the mold trying to alter it. It can be done if you have a gear sample in pristine condition. Too bad they're not molded onto the axles when they're cast.

[Rayman4449]

Very interesting on the engine.  Are those the original sliders?  Well the elimination of the tires may shift some of the load to the other wheels but only two of the axles of the three really carry much of the load because the floppy axle is spring loaded from the top which limits what it actually adds.  I dunno this is an area that I know there are varying opinions on but I strongly believe in using/keeping traction tires as because cause of how light these engines are as if you remove the traction tires you greatly reduce their ability to pull a load and start facing the need to add weight.  On any of these engines when you start having to add weight (when no traction tires are present) you have to add a significant amount more weight to gain appreciable increases in pulling power. (as opposed to if tires are present).  On the USA engines they transfer their engine weight to a small pin on the outside wheel via a bushing on the truck frame.  

 

In these pictures you can see the wear in the two locations (on a USA three axle truck): (note that these photos are from engines with no extra weight added)

 

First picture is of the third axle bushing: (some wear but not much)

 

 

 

Second pic is of the center axle (number two axle):  This is where most of the engine weight is transfered)

 

 

 

You can see just how bad the wear is in this case.  Now you may not have this much wear on your engines from your level of use but it underscores what can happen just from wear just from normal weights.  As you add more weight this wear will accelerate because the contact point (surface area) on the pin to the bushing is relatively small.

 

In the end I don't think it's critical that you leave them in place, but if you find yourself having to add weight to regain lost and needed pulling power then I would keep this in mind and try and use your best judgement as to what additional might be ok to add before you might consider going back to traction tired wheels.  If then engine is still pulling fine and you don't need to add weight then you have probably done the right thing as that should extend the life of all the gears by shifting the load to the other axles and also just allow for a little more slip in some cases when it's probably no noticeable or important.

 

As a note, these photos were from engines that saw quite a bit of use and would expect the avg user to not be having significant issues with this.  Keeping these contact points oiled is important to keep wear down to a minimum.  If someone does have wear problems they could just buy replacement bushings and be good to go.

 

In the case of the above photos, I simply rotated the badly worn bearings around 180 degrees (face the worn area down so it's not wearing on the same spot) to delay the need to replace them.