# replacement metal idler gears?: USA



## Enginear (Jul 29, 2008)

I'm not picking on nothing here. What I'm wondering is if anyone has replacement metal gears for the insides of the USA trucks. I have an old SD40-2 that I believe has some serious troubles. It has always been loud. Recently it got quieter until finally it just sat there. I opened up the gearboxes to find some stripped idlers. I'm not crazy about how the trucks are designed. I pulled the idlers off of the front pivoting axles because they don't do much for traction do they? I used those idlers to replace the stripped ones temporarily until I get more from USA. Now the engine is loud again. I used to think that's USA's typical sounds until recently I got some new ones that are quiet and smoother. So now I'm wondering if these truck's bodies are warped or something's out of line??
I'm thinking that they should have metal idlers that might hold up better against the worms. Do the idlers strip for you guys? I've read a lot about broken shafts. I'm thinking maybe the idlers aren't a usual problem then??Is it just this one?? I will find out in time now that I have more USA's running. I just think that metal idlers would last longer??


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## Greg Elmassian (Jan 3, 2008)

Unusual to have wear on these, never had one wear out. 

Believe it or not, I'll bet you did not get the gearboxes back together right... very common and easy to do, even if you are experienced. 

How do you align the brass bushings on the main axles when assembling and how do you keep them from shifting when putting the gearbox cover back on? 

I've got about 20 USAT locos, and the only one that had gearbox whine was one I put back together wrong. 

Greg


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## Enginear (Jul 29, 2008)

Yeap, but I studied them pretty well. I have the idler bushings square in but the axles I have at 45degrees as they came out. I was going to try the axles also square in. I already spoke with some guys about this. We were thinking that maybe the truck housing is warped somehow. This engine came from ST aubins closeout years ago. It was very loud from the factory. It was my second USA and the other was loud also. I had always thought it was normal. My newest ones are silent. I'm thinking of try some shims or something to fix the binding noise. I would hate to have the gears loose. I was thinking that metal gears might be better when adjusting?


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## SD90WLMT (Feb 16, 2010)

Joe, why not try bench running the power trucks - only one at a time to better listen or feel for the problem you can hear... 

As a mechanic I used to use a long screw driver against my ear to listen for non-normal sounds to locate a problem,.. 

also a used stethoscope works very well as a listening device... 

What I am offering will allow you to nearly pin-point the origin /or place of your troubles.... 

Also does the truck 'rock' on the track - an indication to me for the warped housing your considering.. 

Break down each idea you have into single points to detect and solve your problem, it will be easier to figure out and fix.... 

Hope this helps some!! good luck - keep working on it!! 

Dirk, and share here,.. so we can learn,... toooooooo oooo!!


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## SD90WLMT (Feb 16, 2010)

dis-mantle the parts and run the motors only, then add the idler gears one at a time, then add each axle again one at a time, till you find the noise problem... 

Breaking it down into manageable steps will reveal the issues.. 

Dirk


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## Enginear (Jul 29, 2008)

Good advice Dirk. When I opened up the trucks, the idlers were all chewed up. It was where they hit the worm. I would start there as it appears to be the spot where trouble is happening. It could be just the weakest link though.


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## SD90WLMT (Feb 16, 2010)

Certainly the interface between a worm and gear is unique, compared to normal gears just turning together. Think of a transmission - in low gear here transferring the greatest load. 

Any load on the gear train will increase the strain on the gear train, but the power will build up and cause trouble in the highest load area, in this case the worm/gear set. 

So while the worm/gear are chewed up, maybe too much load has been placed on the loco, poor grease habits on the previous owner, any number of possibilities here. 

Did kids play with the loco....? 

Keep working away... Dirk


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## Greg Elmassian (Jan 3, 2008)

OK, well USAT does some weird stuff... 

The axle bushings MUST be at 45 degrees. If you put then "square in" you will destroy the gears. Note that the "floppy" axle may be different, although I seem to remember it's "points up" as you say. 

Also, since the 2 axle blocks, like the F units are "square in", you will find TONS of people SWEARING one way or the other for ALL USAT... the way you know you have an "expert" is that they tell you right away that the 3 axle systems are done the opposite of the 2 axle. If they don't know that, they are not experts.

You will also note (no offense) that people who do not know this will have gear problems, noise or gears being damaged. 

One thing that contributes to the misinformation is that when you pull one apart, it's REALLY easy for the axles to shift and pop out a bit and the axle bushings to change position. So people "see" them wrong easily. 

Also, reassembling is tricky, best techniques to hold everything in place so they don't pop out as you put the cover on is either rubber bands around the backside holding the axles in place (if the motor block is out) or screwdrivers under the truck assembly, pushing it away from the chassis (blocks in) 

Trust me, I've done it wrong a couple of times even taking great care... those little buggers want to come out and misalign at the least provocation.

By the way, metal idler gears would increase noise, as metal gears always do.

Regards, Greg

p.s. I am not an expert, still learning... 
Posted By Enginear on 28 Dec 2012 05:56 AM 
Yeap, but I studied them pretty well. I have the idler bushings square in but the axles I have at 45degrees as they came out. I was going to try the axles also square in. I already spoke with some guys about this. We were thinking that maybe the truck housing is warped somehow. This engine came from ST aubins closeout years ago. It was very loud from the factory. It was my second USA and the other was loud also. I had always thought it was normal. My newest ones are silent. I'm thinking of try some shims or something to fix the binding noise. I would hate to have the gears loose. I was thinking that metal gears might be better when adjusting?


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## SD90WLMT (Feb 16, 2010)

Just a side note here,... 

Yes - metal gears make more noise, but only if 2 run together!! 

Pretty hard to make noise if one is nylon or plastic or .... 

I know I'm not an expert, but do not have broken power trucks either, that's how I know I'm not an expert - nothing broken, so,... I must be doing something wrong!! 

Dirk


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## Enginear (Jul 29, 2008)

Well..., thanks. This SD40-2 was new when I got it. I never overloaded it and it has always been loud. It was a bugger getting those bearings all in the right way and place so I'm not looking forward to opening it up to play around. It's good to know this isn't regular so I can look for something just in this engine and not expect it in my SD70MAC. I believe I may have an oddball then. I had another loud one way back and I bought a dummy that was stripped of all gears. I had wondered if it was some bad run of these from the past.


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## SD90WLMT (Feb 16, 2010)

not trying to step on toes !! 

My 70 runs incredibly well... 

No reason the 40 can't run well also!! 

Dirk - send a pm and call me!!


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## SD90WLMT (Feb 16, 2010)

If you have followed MY threads on the DDA40X or My layout, You may have seen the 'custom power trucks' I have basically bashed into what I needed as a truck!! I do not know of anyone else that is bashing power trucks............. 

I have taken them apart numerous times, do not have difficulty working on them, do not put them together in-correctly as some seem to have done..They all run well and smoooothly. 

I will do what ever I can to help You here Joe!! 

I even have some SD40-2 trucks here we can doing something with.. I'm not using them...brand new - un-run.... 

Dirk


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## Greg Elmassian (Jan 3, 2008)

On occasion, a "new" loco has been returned, and has been "played with".... many people here will testify that they have received "new" items that had clearly been run, repackaged, etc. direct from Charles Ro / USAT... 

So, this is not typical, but clearly not impossible. 

Sometimes I would swear that one got assembled wrong from the factory too. 

In any case, it's not typical, and once you replace the damaged parts you should be fine.. 

Greg


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## Enginear (Jul 29, 2008)

Ok then Loud it is! I'll try something else when I get time. The idlers seem to only go in one way. If I rotate them to 45 degrees, they don't engage. STill very loud. These idlers lasted a couple years now. I'm running inside for the winter. The plywood tables magnify the sounds. When it was outside, it wasn't very noticeable. I get the feeling it's just a tad off.


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## Gary Armitstead (Jan 2, 2008)

Posted By Greg Elmassian on 28 Dec 2012 01:14 PM 
On occasion, a "new" loco has been returned, and has been "played with".... many people here will testify that they have received "new" items that had clearly been run, repackaged, etc. direct from Charles Ro / USAT... 

So, this is not typical, but clearly not impossible. 

Sometimes I would swear that one got assembled wrong from the factory too. 

In any case, it's not typical, and once you replace the damaged parts you should be fine.. 

Greg I happened to notice this thread this morning and decided to comment. I bought a brand new USAT SD40-2 back in 2000, from the Train Shack here in Burbank. It has been run ONLY twice....around the pool for two Christmases and less than 30 minutes each time. It is noisy, but not so much that a sound system wouldn't cover that. It also is a very smooth runner using an LGB Jumbo Pack.

I've been talking to Paul Burch, trying to decide to do a Battery/ Airwire/Phoenix install on this engine, by myself! Yipes!!







This is for the New Year.


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## SD90WLMT (Feb 16, 2010)

Gary - what color loco would it be?? 

Dirk


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## Gary Armitstead (Jan 2, 2008)

Posted By SD90WLMT on 28 Dec 2012 02:15 PM 
Gary - what color loco would it be?? 

Dirk Old Southern Pacific "gray".







I've forgotten the number....still boxed up in the "engine barn"....garage.


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## SD90WLMT (Feb 16, 2010)

well good,... 

SP works for me also! 

Hoping to complete MY dash - 9 repaint - SP, filthy, in the spring time... 

Dirk


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## Greg Elmassian (Jan 3, 2008)

Gary, you might see if it's only from one motor block. 

Also, if your first USAT with the "floppy" axle, read my tips on my USAT PA page, will really help in how it runs... 

Greg


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## SD90WLMT (Feb 16, 2010)

I'm laughing now!! 

It's funny we broached this subject. 

I have on the kitchen counter today's fun project. Just to work on something in the cabin. 

I have a set of the 70 mac trucks off the loco, and I'm in the process of improving the issues I just read in your tips section Greg! 

Two things I have done are 1. reduce and limit the side to side movement. 2. increase the spring pressure to actually help the forward floppy axle 'do some work'.. 

My finished trucks can travel thru a 60'' / 5 foot radius curve, off the loco.. 

If one was to lift and feel how 'light' this axle is, you'd wonder how it adds traction to the truck.!! After adding a beefier spring, and then lifting it again, I have found it to be every bit as 'heavy' as the other 2 axles are on the fixed block section. 

The trucks I have modified have never, never caused any more trouble while running. 

Food for thought!! 

Dirk


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## Greg Elmassian (Jan 3, 2008)

Yep, think I might try your idea on my PAs... and will probably ask to post some of your photos on my site. 

Greg


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## SD90WLMT (Feb 16, 2010)

While working on this, I am saving info for reference also! 

pix, dems. - next trip to town I'll get the part number for the spring I use.. 

Put it all together in one place!! 

What is interesting is what possibly happens to this truck with the mods I do. It evens out the loads over all the axles, thereby actually 'reducing their individual loads', by allowing all axles to do equal work. This means it lowers the risk of breakage, axle gear strain, etc. 

A stock truck only works two axles for the most part. I feel the floppy axle is not in a position to create very much in the way of traction, it just goes around. With out any weight bearing down on the axle, it can not generate any tractive effort. ( very little, to be at all effective ) So with increased pressure this changes the game! As such it "balances" the axle loads, and I'm leaning towards it also reducing the problems associated with running the rubber traction tires also. 

On My own loco with this set-up, and full traction tires, ( here comes the flame wars - warning - again!! :~ } ) Yes all 12 tires, I have not had any of the typical problems with gear breakage.... 

It pulls 8.5 pounds of tractive effort - very few LS locos can & do pull this amount. 

I work this loco as I have shared in other posts - it is not a "trailer Queen"... 

One last thought here, and a recommendation also, this truck as I now have it should either run all 12 wheels with tires or none, not a combination of mixed wheels. This would lead to the obvious "imbalanced' problems all over again...so it can be all - or - nothing here.... 

Dirk - DMS Ry.


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## Greg Elmassian (Jan 3, 2008)

I agree on the balance part...


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## Gary Armitstead (Jan 2, 2008)

Posted By Greg Elmassian on 28 Dec 2012 02:36 PM 
Gary, you might see if it's only from one motor block. 

Also, if your first USAT with the "floppy" axle, read my tips on my USAT PA page, will really help in how it runs... 

Greg Yeah, this is ONLY my second "dis-easal" purchased. Also my only purchased of a USAT loco. I'll take a look at your tips. I also have a set of LGB Santa Fe Warbonnets ABBA, that I purchased NEW for my late father, that I'm thinking of converting over to battery.


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## Dick413 (Jan 7, 2008)

Dirk 
I have a ? have you ever thought about just making the 3rd axle fixed to the other 2 ? 
your layout is so big it does not need the swing from 3rd axle 
Dick


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## SD90WLMT (Feb 16, 2010)

Dick - very good? here...!! 

Granted on My layout the small amount of swing is not needed,... 

But there is one concept still important here, maintaining traction on all drivers all the time. What I mean is this gives the truck the flexibility to work over ups and downs without lifting a driver set off the rails..any twisting in the track or vertical changes would other wise leave the truck lifting the center axle off the rails, or over a hump will lift one or both the front or rear axle off, thus reducing traction. I'm sure this would be short lived in most cases, but we do not live in an ideal world, even for toys. I felt it was more important to keep all the wheels on the rail all the time.. Call it suspension........... !! 

Excuse me - had to go see what the rumble was about... 5 lead locos - a mirror image set - 70Ace, 70M, -9, 70M, 70ace...all elephants;.. pulling 40ft. stacks, about 106 of 'em , with bare tables following, heading for John's home.. and these were full heavy cars!! All 135 of em.... 

Dirk - DMS Ry.


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## Enginear (Jul 29, 2008)

I like the idea of loading that axle. It may as well be doing something. If possible maybe a simple compression spring against the floor? Dirk, I have watched you modify your trucks. I like that whole build. We both got to get motivated and finish our projects.


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## SD90WLMT (Feb 16, 2010)

I install the replacement spring in the original position,....no prob..lem 'o'...! 

A bit stiffer, but it gets cut down to be manageable... I do need to figure out how much is needed for a standard 10 pound loco however, as mine is lots heavier and uses the spring strength I add, trail and error here! 

Also I have noticed a handling ( people ) problem with trucks. The metal slotted plate we are discussing here sometimes is bent, across the slot opening on both sides.. does not seem to cause a real problem, but I always put it back into service only after straightening it first!! I have found these on both new locos, and new replacement service parts. 

OK - again - you guys are making me count cars more now!! ha .... 3 locos - 40' stacks - west bnd. 135 cars, again! 

I know what you mean about getting work done Joe, it is real hard here in the winter.... So I have been distracted by the little bit of truck work today!! Wish I had more room in the cabin,. let's see.... more tools,.... a bench, ..........well it just won't work... :`\ 

Need to build is all!, 

Dirk


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## Michael Glavin (Jan 2, 2009)

Dirk,
Is there a thread on your truck modifications, especially the modified wheelbase trucks? I have a trio of Krauss Maffei ML-4000’s that require some short 3 axle trucks, looking for ideas on shortening Aristo or USAT trucks. 

Michael


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## SD90WLMT (Feb 16, 2010)

Michael, do you have any dimensions for the axle spacing...? 

All my trucks have maintained the same USA wheel base... 

But what do you have, I can figure it out real quick!! 

Dirk - ...truck in front of me. ha!


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## Michael Glavin (Jan 2, 2009)

Dirk,
Truck wheelbase is 4.75”, with equal axle spacing of 2.375”.

I don’t want to derail this thread with my fodder, I’ll try and PM you…

Michael


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## Enginear (Jul 29, 2008)

I just replaced a set of wheels with tires with solid ones without tires on my SD70MAC. One truck has a heavily worn idler on the middle axle? I'm seeing this again so maybe it is a problem. This engine was bought used. It has grease inside and isn't dry. I don't know it's useage history. I find it odd that I'm 2 engines for 2 with these idlers and no one else has a problem? Well this one is not stripped totally. So maybe if I didn't open it up, I would not have known it was so worn.


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## SD90WLMT (Feb 16, 2010)

If or when you have a complete - all put together loco again - place it on a desk - kitchen table or even up on a shelf where it will be easy for you to view it side ways!! 

Take a medium sized screw driver and gently 'lift' each of the 3 axles ( wheels ) one at a time... 

The floppy takes no effort.. 
the mid axle lifts against the suspension ( frame ) and then the entire loco is lifted upwards... 
then the rear axle tilts the side frames, but is not lifting the loco... 

No weight on the floppy.......... 
Mid - the greatest weight... 
Rear ( with rubber tires usually ) lifts with a bit less than the mid axle does.... 

Conclusions here for ME.. 

the heavier spring I use makes the floppy carry weight and produce traction.. 

The mid remains as is... 

the rear remains as is... 

................... now on My loco ( SD70 ) the floppy is currently the heaviest axle to lift! great... the mid lifts the loco, and the rear lifts - still - a bit less than the mid 


Big conclusion is the Mid axle does most of the 'work' on a 'stock loco out of the box' - that's mostly one axle from 3 - doing most of the work - so it seems reasonable that your found the worm worn more than the others...!! 

I did get off to the store yesterday afternoon, picked out several springs that are good to install in place of the stock weaker spring found on the floppy axle used currently..and I got the part numbers also!! So I will put together all the info & pix I have and get it posted ASAP in the next day or two...!!! 

Dirk - DMS Ry.


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## BarrysBigTrains (Sep 4, 2008)

Just one little tip, especially if you are going to run all metal gears. 

One cardinal rule: The driving gear must be of harder material than the driven gear. 

The price is to wear out the driving gear very quickly (compared to how it might have been). 

Barry


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## Greg Elmassian (Jan 3, 2008)

One other thing that happens pretty frequently in our scale, is the power to a truck can be interrupted (the Aristos with the flimsy contacts on top of the motor brick are famous) and one truck will drag the other truck and boy will that chew up gears fast... 

Another thing specific to USAT is the "cracked axle" syndrome, where the axles are actually loose in the plastic casting... thus there are fewer axles driving... usat locos need to be checked on a regular basis, it's NOT readily apparent visually. 

Greg


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## Chucks_Trains (Jan 2, 2008)

As was suggested earlier I plate all my USA 3 axle drives. When plated a stock loco will actually have less drawbar pull/ tractive effort as the weight is now spread out on all 6 axles..not 4. You can change the spring rate on that floppy axle until your heart is content but it's not going to change a thing..the engine weight itself is going to dictate TE as in axle loadings.

As far as wanting a working suspension..huh? These things don't have a working suspension to begin with as they're all oversprung...The only engine I have that actually somewhat works in the suspension area is my USA Hudson. Aristo drives have no suspension..only an axle that can rock on a 3 axle drive. Big flanges keep the wheels on the rails. Read the articles about the folks that tried smaller flanges on Aristo drives.


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## SD90WLMT (Feb 16, 2010)

Chuck, short 2 ?'s for you!?? 

Are you running track or battery power in your locos? 

How are you determining TE on your locos!?? 



Dirk


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## Greg Elmassian (Jan 3, 2008)

Theoretically tractive effort is mostly determined by weight, given the same weight of the loco, the tractive effort should be same no matter how many wheels are in contact. (assuming you are putting the weight on driven axles). 

If you add some weight, you can get some compliance out of the USAT suspension, such as it is. Yes Aristo has no suspension and depends completely on flanges especially in the 3 axle blocks. I've found that reducing flanges under 0.1 or so makes it almost impossible to have reliable running on most layouts. 
(that is a BIG generalization, so of course many people will be an exception who have very flat layouts and good trackwork) 

Greg


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## Chucks_Trains (Jan 2, 2008)

Dirk, Track power..Whatever I feel like running as some engines use MTH PS2 and track power, some engines use QSI, track power & Gwire or battery and some can use DCC..guess you could say that I'm shifty









Greg, You know that floppy axle doesn't do sh*t in its stock form so technically say a SD40-2 has all the weight on 4 axles..plate the floppy axles and now the entire engine weight is on 6 axles. I did a before and after drawbar test using a digital fish scale as the dyno car is being rebuilt. After I plated the drives the drawbar pull went down. It does make sense when you think about it.


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## SD90WLMT (Feb 16, 2010)

Thanks Chuck, 

As Greg noticed also, I picked up on the contradiction in your statement... 

I was interested in your power means as a guide to loco weights.. 

While we have had differing experiences with our toys, resulting in a wide difference in our views, I think we might be on the same page!! 

Glad to see you have used a scale to measure with.. do you have any written results from using the scale? 

I would be wanting to compare the efforts of a stock loco to one with a solid plate, and then the percentage of decrease in total overall effort. 

Unfortunately in my case I had no idea to capture any results before my mods to a loco, too many people complained of many issues and I just plowed ahead into what I now have running. Btw - this was the result of My first attempts - not from numerous trials or experiments, just the first hat trick! 

And I run - only battery power which is heavier, in fact for the trucks I just converted for a Friend, we talked on the phone to come to agreement for final weight, in his case and use, and set a 14 pound weight, which I used to determine alternate springs.. 

I will do a complete write up and photo thread and post it this week!! 

Also I did like your results of a nice clean plate to bolt to the bottom!! 

Dirk - DMS Ry.


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## Greg Elmassian (Jan 3, 2008)

The laws of physics make sense... and if the drawbar pull decreased, something else happened... it should have increased. 

If it did not, then there are some other interesting things going on. 

So far, the laws of physics, and kinetic and static friction have held true ever since they were discovered, before any of us were born. 

Guess I'll have to investigate. 

Greg


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## Enginear (Jul 29, 2008)

Hmmm, I took apart my MTH trucks to make sure they have grease. After nearly a decade, there's no wear that I can see. All the gears look metal. No difference there on any wear towards the driving gear. I think if they are hard enough to handle the task, there doesn't have to be a sacrificial gear. Wheel slip should occur before gear failure.


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## Enginear (Jul 29, 2008)

I would think that if drawbar pull decreased an axle that was unevenly doing more work lost something?? Just a humble guess??


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## Greg Elmassian (Jan 3, 2008)

Enginear: 

I want to caution you to something I will be sensitive to, so let's not go there.... a while ago a certain group went on and on about the all metal gears in MTH and that everything else was crap. Same people have posted such on youtube. Same people have written letters to the forum owner to try to get me thrown off the site because I was "bashing" MTH... 

I don't doubt that MTH makes great gearboxes. But not all good quality trains HAVE to have metal gears or else. 

So, let's not go anywhere near there.... If I had started in 1:32 I almost certainly would own everything MTH makes in that scale. 

On a much happier note, wheel slip should definitely occur before gear failure, complete agreement. With the problem with "cracked axle gear castings", and then putting traction tires on only a few of the axles, I think USAT makes the problem worse... and the traction tires can REALLY add to the load. 

These are my findings, although after putting sleeves on my "cracked axles" I have no more slipping wheels... granted I removed all traction tires and do not overload my locos (I believe), I have never had a gear fail on a USAT loco and I have about 20 of them, many of them 10 years old. 

So, a decade of plastic gears IS possible. 

Best regards, Greg


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## SD90WLMT (Feb 16, 2010)

Let common sense prevail - please..!! 

OH, just observing here!! 

hi guys! 

Dirk ,..... :~ } 

50 car trains seem longer than most run Greg! 

Dirk - DMS Ry.


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## SD90WLMT (Feb 16, 2010)

Do we have any guidelines for those pesky ?'s - like what defines... ''overload'' ....? 

a certain number of cars 
a certain amp load range 
a particular grade 

or - a combination of these quantified into results that break toys....? 

D


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## SD90WLMT (Feb 16, 2010)

And then we have the apparent issue of no one agreeing on any data to form a base set of guide lines from... 

Each has their own selective ideas of what works or does not work... 

Try this word - subjective - what does it mean? Why do so many use this 'word' to form their opinions from, rather than cut and dry facts!?? 

Facts from a very use-full basis to compare one item to another, and leave our precious feelings out of the equation - so we can reach an intelligent conclusion, and move from one point to the next as we gather info. 

Why do we as humans 'fear facts' - maybe they are not as we want to believe,.. because we will not accept them and disagree, just to disagree at times... 
What does it prove - or solve ....? 

anyway - just thoughts here, nothing more,.... everyone seems on edge - cabin fever perhaps,..mmm - it's winter - it's cold = we can't do what we want to do,. go out and do - Play trains!!!!! YA!!! 

Sleep - rest - be well.. I know I deserve to have cabin fever, after all I do indeed live in a cabin! 

Dirk - DMS Ry. some think a long train is 10-12-15 or even 20-25 cars, maybe 50 cars, or could it really be a 100 car train.. or more?,.. depends on ones layout is the most common basis for an answer .... mmmm much to ponder.


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## Chucks_Trains (Jan 2, 2008)

As Greg noticed also, I picked up on the contradiction in your statement... 

Elaborate if you would??!!


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## Chucks_Trains (Jan 2, 2008)

Theoretically tractive effort is mostly determined by weight, given the same weight of the loco, the tractive effort should be same no matter how many wheels are in contact. (assuming you are putting the weight on driven axles). 

It is but it isn't..you have to factor in adhesion just like the real rr's do as they only figure on maybe 30% and as low as 10%..EMD makes an outstanding claim at 50% but from what I've read don't count on it unless your going over 24 mph. 

Our little toy trains are probably about the same or less..like maybe only 10% adhesion on non-traction tire equipped axles esp. considering how light they are in the stock form. Traction tired axles are probably up in the 90% adhesion area. My plated 3 axle drive locos all have traction tire axles located on most inward spot closest to the fuel tank. When I plated them it must have pulled considerable weight off those axles and shifted it to the floppy axles. So if the traction tire axle was doing 90% of the pulling and the plating removed 50% of that adhesion and the other 2 axles were doing maybe 10% then that engine would be at only 70% adhesion of what it was before the plating. 

I know that a stock SD70MAC can't pull 11 Aristo heavyweights around the layout but my SD40-2's or PA's will do it as they have traction tires. 

I never added anymore weight to any engines after plating the drives as why push the crappy design any harder & strip gears? I wonder about making one of my SD40-2's all traction tire axle equipped? 

Don't admire my plating as I copied Marty Cozads plating from years ago. 

I run 100' long trains..just feels right!


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## Greg Elmassian (Jan 3, 2008)

Adhesion is directly related to static and kinetic friction. Research those and you will find that this is controlled by only 2 factors, "normal force" (normal means the downwards force, i.e. the weight) and the coefficient of friction for the material, and in this case the coefficient of static friction. 

(kinetic friction is when things are moving / slipping, and as you can understand, normally less than the static friction, that's why when a loco wheel slips, you have to reduce power by more than the point at which it broke free) 

That's it. That's why it's simple. If this is not true, there's something wrong in the calculation or measurement. 

Of course the coefficient of friction for rubber on metal rails is different than metal on metal rails. (this is why automobiles have rubber tires and not metal ones). 

Also, different metals for plating the wheels will cause a variation in "traction".. I can tell you there's a much bigger difference because of the rails, my stainless is much slipperier than oxidized aluminum. 

Greg


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## SD90WLMT (Feb 16, 2010)

Chuck, I'll elaborate for you! 

''When plated a stock loco will actually have less drawbar pull/ tractive effort as the weight is now spread out on all 6 axles..not 4. You can change the spring rate on that floppy axle until your heart is content but it's not going to change a thing..the engine weight itself is going to dictate TE as in axle loadings.'' 

1. - You mentioned less draw bar - T.E when using all 6 axles '' as the weight is now spread out on all 6 axles..not 4'' 

then,.. 

2. - You say this - ''the engine weight itself is going to dictate TE as in axle loadings.'' 

To MY thinking you can't do it both ways... that's all... 

In My stick drawing below it is clear that on uneven track some wheels are not always in contact with the rails, which will reduce friction, adhesion, and T.E. overall.. 

 

The point of the frame pivot also is important here... If you increase the floppy axle adhesion, it will require more weight on it, by increasing the spring pressure on top or adding more ballast on the block housing. But notice the fulcrum pivot points in play - to reduce the rear axle effort as you suggest means lowering the front axle a great deal to overcome the nominal 5 pound down force from the loco frame sitting on the truck. With a rigid block the wheels are not going below the rail grade to achieve this concept... 

Most of the loco weight sits on the middle axle, by increasing the spring rate the loco weight is divided over 2 points to further press all the axles down on the rails.. 

When I tinker with ideas - I usually expect an improvement in performance. If for some reason My ideas don't give the desired results, I try to figure out why. at the least I know some thing is not right with the parts - the combination - or maybe just the concept overall.. 

In your case of reduced traction effort for the change / improvement you made - to me it is sort of like a red flag - something about the idea is not working properly... 

You have not given any data for your effort. so I can't make any real sense of it all, sorry. 

I do have data, My efforts have been documented and produced results beyond expectations.. 

I seem to be the 'Lone Wolf' in this camp, at least no one has admitted to doing this,.. Yet... 

My loco runs FULL traction tires.. has not broken, has been run at current levels ( amps ) that equal the rated motors in use ( 6.0 - 7.1 Amps, at the loco ) - Stock motors never changed, with gear train that has never been damaged or replaced...no loose - broken axle gears with sleeves added for support.... 

It runs at levels of traction that rival most locos we have available to play with in this scale. 

So for all it's mods - it runs at nearly 44% tractive effort compared to it's base weight, of 19.375 pounds! 

I'll repeat the point here - IT has never broken.....it has run very hot, but not damaged the motors, I also am convinced I have not tested it to it's absolute limits yet ..which currently are 8.5 pounds of pull on the coupler... 

can you explain why? 

No one has done this... I made changes and achieved a corresponding positive result...seems like it works!!!!! A balanced motor block does and can work very well...with suspension .. 

PS. - SD40-2 - weight, 368,000 pds., 92,000 pds. T.E. - 25% 
.......SD90 - weight 415,000 pds., starting 165,000pds, T.E. - 39.7%,...200,000 pds., 48% running 
.........BiG Boy - weight 540,000 pds., on the drivers - 135,375 pds., - T.E. 25% 

just for a better reference here, real locos 

Thank You, 
Dirk - DMS Ry.


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## Enginear (Jul 29, 2008)

Well... Ok then. I guess I would say that if you didn't like a certain manufacturer for their trucks design, you would hold them all to the same level. I won't pick on you for liking USA trains. They make great products and are very innovative. They have some flaws I think. I'm trying to solve them. So let's not compare anymore brands and lets just talk this one. It appears that USA changed out the axles with tires as my older SD70MAC has them yet my newer one does not. Would that be correct?? I would only guess at why if so. Maybe for some other reason than gear fatigue?? They already have slider shoes so I would think the electrical pickup was already good enough?? 
The reason I'm on this subject at all is because of what I see. Now only have five USA locos here. The only two used ones when opened up show excessive idler wear. It pushes me towards thinking maybe they need upgrading?? If no one else sees idler wear than it must be just my two models are different???


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## Enginear (Jul 29, 2008)

" I want to caution you to something I will be sensitive to, so let's not go there.... a while ago a certain group went on and on about the all metal gears in MTH and that everything else was crap. Same people have posted such on youtube. Same people have written letters to the forum owner to try to get me thrown off the site because I was "bashing" MTH... " 
???? 
I must have been away from the forum when this happened?? The fact that you seem to take ownership of this forum and my post when I'm taking to anyone who wishes to discuss things troubles me. If I can't express that I like a brand, then i hope it's universally aplied here to all. 
Your history must be causing sensitivity which I can understand by the tones I read on some posts by all. Forums can get heated. We'll tone it down and let's talk reasonably. Some times it's hard to do when you're (we're) passionate about something. Brand wars definately can bring this out!! So, if we can talk about why my gears failed, lets continue. If not, I will replace them (as I already did) and move on while pretending it never happened. Seeing other posts about discussing problems encountered led me to believe, this forum could help.


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## Enginear (Jul 29, 2008)

Posted By BarrysBigTrains on 30 Dec 2012 02:30 PM 
Just one little tip, especially if you are going to run all metal gears. 

One cardinal rule: The driving gear must be of harder material than the driven gear. 

The price is to wear out the driving gear very quickly (compared to how it might have been). 

Barry 
I was referring to this passage Greg. i don't know why I can't respond to it? If you think this concerned you, I'm sorry?


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## SD90WLMT (Feb 16, 2010)

I'm curious more now Joe, did you or did you consider replacing all the idler gears, or just the worn ones!?? 

I'm thinking all could be changed to start on a fresh - level playing field, under your care and use, so as to have the best go at it from here on out! 

Don't know how this may compare, but since I have been a mechanic much of My life, I have here & use a very fine White lithium grease on my gears... 

No problem from it yet either...Just make sure everything is well coated, some comes off from running also, noting a spray effect on covers after I remove them to work inside.. 

Dirk


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## Enginear (Jul 29, 2008)

Dirk, I've been using the grease in a kit I bought for model trains. It seems to stay put and I check back yearly to make sure it's still full. Maybe the factory grease is no good? 
One of my USA's, the SD40-2 CBQ, I bought new. I have been the only owner. I replaced all the idlers now but it's always very loud. It's an older model so maybe the gear box noise can be overlooked. I will replace them if needed. When I got my next one, an SD70MAC it was quiet so I did not expect to see any wear like that on the idlers. I did and that's why I asked if others have seen this. 
Apparently you don't question a certain brand here on the forum? Where as another certain brand is fair game for attack??? I even see posts of the other brand saying it's junk??? Where's the definitions so I can read them. I'm pretty happy with all the brands. I strive to make them run as perfectly as i can achieve. I figured we could talk about this together but, I will hoard stuff to myself and you guys can complain like a fraternity I guess. 
Maybe that's why i was asked who did my last command install? Is there something more going on here? Too bad. I don't need a person who responds to everything i post as an attack on him. On another forum there's a link to ignore posts by people you don't want to see. Maybe that's needed here for some? I would have expected a company representative to behave this way. Hmmmm............ 
You guys should learn that several people out there may know just as much as you. When they ask opinions, try to respond well. Maybe they're just looking to discuss options. Maybe they want to see alternatives. Maybe they will think this is a good place to be. Maybe you don't want any new frat members?


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## Chucks_Trains (Jan 2, 2008)

Dirk I guess that you didn't read my next post eh? I said that weight got pulled off the axle with the traction tire and put onto a plain wheel. The traction tire axle lost probably 50% of it's adhesion and that weight went onto an axle with maybe 10% adhesion. 

Suppose you never read of the old boys that ran steam? They could go underneath and change driver axle loadings in a matter of minutes by wedging the bushing boxes thus changing the TE. the Russians did it all the time when going from a "heavy" road to a "light" one...they'd go downstairs and change axle loadings. 

I'm sorry that you don't believe me about how plating the drives will change the drawbar pull. I was surprised myself when I seen it. 

I don't believe a lot of your claims...where's the proof?? What loco are you talking about? Is it on You Tube or will Dennis Sirrine vouch for it?? I email with him quite a bit so I'll ask! 

BTW.. a real SD40-2 ballasted heavy like on the BN mountain routes used for coal drags weigh in at 420,000 lbs. w/ 126,000 lbs. TE @ 8.9 mph 
An SD90 won't do what you claim..not below 13 mph they can't utilize their 6,000 hp. as they'll start spinning. SD90's are good on high speed intermodal freight..SD70 MAC's and the old SD40-2's are the loco's of choice on the hard slow pulling. 
The best record I've ever seen for a U.P. 4000 (that's a Big Boy) is 115,000 lbs. drawbar pull..and that was well documented.


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## SD90WLMT (Feb 16, 2010)

You picked a surprising person to vouch for MY loco, while several others on this site have seen it run first hand! 

Dennis - indeed has seen My loco. It has in fact run on his layout before!! 

I am discussing My SD70 Mac. 

nuff 'fer now tho! 

Dirk


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## Greg Elmassian (Jan 3, 2008)

I hope we give all brands a fair shake, and concentrate on fixes to improve them... now that will require being objective on problems and issues. 

I try very hard to be objective, and factual. For example I often comment on the ruggedness of the Aristo drive, but I've seen some examples here that I've never seen. 

Learn something new every day. 

P.s. could I have permission to use that "axle collection" on my site? 

Greg


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