# Aristo drivetrain design and it's ramifications



## Greg Elmassian (Jan 3, 2008)

Over on the Aristo forum, there seems to be a constant discussion about the problem with maintaining quartering on steam locomotives. (I am talking sparkies here) 

Since I got yet another nasty response from an Aristo employee (making a suggestion that there is a FAQ forum), I will post my Aristo opinions here. 

The Aristo design differs from "traditional" drivetrain design. 

One design is very analogous to a real steam loco, the power is transmitted among the drivers via the connecting rods on the drivers. 

Of course in a real steam locomotive, the power from the pistons, but typically in a model, one driver axle is geared to a motor. Then the rest of the drivers get "power" from the connecting rods. 

In order to do this, you need nice tight fits between the crankpins on the drivers and the connecting rods, and good synchronization between drivers on each side. You do not have to maintain "quarter" between the left and right side, but you do have to have all drivers in pretty good synchronization to transmit power. 

Now, if you are building something less expensive, you find a way to have looser manufacturing tolerances, which typically saves money. 

So Aristo had a very clever idea, power all axles via a modular gearbox system. Each gearbox has a female hex "socket" to drive the worm gear, and you can daisy chain them by hex driveshafts in any number you want. In most engines, the driveshafts are also brass flywheels. 

Very cool. The gearboxes also pick up power and have a LOT of side to side play in the axles. 

So now, you can negotiate tighter curves, because of the large amount of side to side play in every axle. 

Of course, now that the connecting rods do not transmit power, they have have nice sloppy fits, saving manufacturing money, and assembly time. They also have to be quite loose to accomodate the side to side motion of all the axles. 

Now, unfortunately there are downsides. To keep costs down, the drivers are not keyed to the axles. So they can slip if not well mated to the axles. Since they are a taper fit, if they were lapped to the axles a bit, they will not normally slip. But an additional problem surfaces: there is no way to adjust the gauge of the wheels. You could narrow the gauge by lapping the wheel "into" the axle a bit more, but all Aristo wheels are traditionally (as are many other manufacturers) gauged too narrow. 

The only real solution is to shim the metal "half" axles where they bolt up to the plastic gear in the center. 

So, it's a clever design, designed to be low cost, and allow the use in many different locos, but it also has downsides. 

There are other tips on this on my site, as there are other issues of power pickup problems and simple fixes. 

This post was prompted by repeated posts on the Aristo site as to why the drivers are not keyed, and why power cannot be transmitted by the side rods. 

Regards, Greg


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## Greg Vocks (Jan 2, 2008)

Here is Aristo-craft's explanation (from their website under model information for the Pacific): 
The new Pacific's six drivers are driven by the gearboxes, not by the drive rods like most model steam locomotives. In the model world, drive rods typically do not efficiently transmit power to the drive wheels. The drive rods are delicate and break easily. This results in low pulling power and poor performance of most steam locomotives. Gearbox driven motor blocks provide better pulling power and more reliable performance. With the new Pacific, the drive rod are along for the ride.


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## lownote (Jan 3, 2008)

I'm having that problem--my aristo Mikado fell off the track from about 1 foot and a half and stopped running right. I'm pretty sure something got out of what in the power block but I could not see it and I sent it back to Aristo 

I think their power train is really good--when it's working it's very strong and very smooth. 

The thing that bugs me about aristo is the train engineer system--I'm sorry I ever started down that road


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## Greg Elmassian (Jan 3, 2008)

Greg, I understand the explanation, my reason for posting is repeated questions on why the design. 

I have a Pacific made by Accucraft that will out pull the Aristo Pacific any time and it gets power through the side rods. 

It's just more expensive to do this way, and I cannot fault Aristo for inventing and using theis this clever modular concept design. 

But, as the thread is titled, there are RAMIFICATIONS of the design, which I have detailed out for discussion. 

Regards, Greg


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## markoles (Jan 2, 2008)

Greg, 

While your post is clear and concise, I have to ask "Yeah? So?". 

The issue of the Aristo steam engine wheel axle design 'feature' has been gone over again and again, pretty much since the Mikado was introduced in 2003. If someone is looking for info on this, that's one thing. But this seems to be just stirring up the pot. On the aristo board, the loco in question did not have quartering issues until the accident (as reiterated by Mike here). A bent connecting rod could be causing this problem as well as a driver could have been knocked loose. I don't think that qualifies as a design failure. Obviously, there was a problem electrically since the on board reciever died. 

I have a mikado by aristo, and removed all the drivers for painting. Upon re-installation, I did not use the right loctite, and had problems. I have remedied that and installed the right loctite, and have not had subsequent problems. I didn't bother lapping the axles, why mess with something that is working? Granted, I don't try and overload the engine with more than 18-20 cars, either (on a 4%+ grade). 

Do I wish that Aristo would revise the current practice of attaching the wheel to the axle with a screw? Yes. 
Do I expect that to happen? No. 
Can I live with the current design? Yes. 

Other than that, why make this post? To tell us in a roundabout way that Aristo sent you a 'nasty' email? 

Mark


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## Torby (Jan 2, 2008)

But Greg likes to stirr pots


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## Greg Elmassian (Jan 3, 2008)

No I don't Tom, and I do not appreciate the remark. 

There is someone asking this question, and the Aristo forum is not the place to answer it. 
I was referring to the post by Sumison, not the thread originator. 

I thought that the question could be answered in an honest and objective way, there's reasons for the Aristo design, and they make sense; but the design has it's compromises if you realize cost is one of the primary goals. 

That's all. And if people want to discuss it, they can here. The design itself is interesting and has it's good and bad points. 
I can live with the design, I have a number of Aristo steamers and I'm a happy guy. 

Regards, Greg


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## Guest (Apr 1, 2008)

Mark, 
I think Greg is just pointing out a flaw that should be taken care of.. the wright way, not the aristo way whitch is to keep putting out flawed products with the same defects over and over again with put addressing them as usual no change there. some people in my opion are just gulable and will buy a product for its name and not its proformance and then will defend it to the end even though its defective????/DesktopModules/NTForums/themes/mls/emoticons/blink.gif but it seems like when you take your picture with POLK it automaticly make you defend there defective products... right .... seems that only certain people are allowed to have an opoin and not others/DesktopModules/NTForums/themes/mls/emoticons/crazy.gif also seems like those that are so called aristo supporters are the only ones that can say anything about aristocraft and kiss there butts/DesktopModules/NTForums/themes/mls/emoticons/whistling.gif. 
but anyway some things will never change,but as long as this site ispay as you go all opions count just not the one way street like over on the other forum../DesktopModules/NTForums/themes/mls/emoticons/blink.gif 
Nick


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## markoles (Jan 2, 2008)

Nick, 

That's really uncalled for, but I am defending the aristo product, and not because I am a kiss ass, as you so eloquently put it. I actually think they make a good product for my money, and feel that I can live with a certain amount of flawed equipment. Hey, its cheap compared with say, Marklin I gauge or Aster equipment or even some LGB product, all of which have their own flaws. I'll ask the question the other way, why are you so quick to crucify aristo? I have yet to see a locomotive from anyone get to the market place with 0 defects from any manufacturer. Many folks do not have problems with their equipment, and that goes for all makes, not just aristo. 

The issue of the wheel design on their steam engines has been beaten to death, and it was unprompted here. If someone has a question, let them ask it. And, if they are looking for info, why not let them do some searches first, then if there are still questions, post? There's a great post on the bachmann board about LGB vs ARisto mikados. If that guy can make it here, and do a search through the archives, he'll find lots and lots of info. Maybe even a picture or two.


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## Greg Elmassian (Jan 3, 2008)

I really do not think Nick was "aiming" at you Mark. 

I was talking about drivetrain design, not wheel design. I was mostly responding about the inability to put power through the siderods. 

I also wanted to discuss it, so I really think that "unprompted" is kind of a strange response, what are the rules to originate a thread? 

Anyway, mayby you should not take my post as putting down Aristo, but EXACTLY what I said, the design has ramifications. That is NOT a negative statement. 

Regards, Greg


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## Guest (Apr 1, 2008)

Mark, 
why are you so quick to defend them????? as far as aristo is concerned, i have more then most and less than some, i have been collecting for many years now and finally i have the chance to run some of the stuff within the last year and NOT one of there produts have run right out of the box so far, be it quartering problems on 3 locos ,all 15 locos i have tested so far have leaking smoke units , some locos wired wrong wheels out of guage and on and on and on with the same old problems from aristo. but the thing that got me the most was when you ask questions about defective items you get NASTY private emails from that joke of a customer service manager that knows nothing about TRAINS...so you can see i do have issues with aristo and there custmer service, by the way maybe its just me, me but when i spend over 400.00 for a loco i expect it to work period nothing less than that is ok. and it seems like for the most part NO other manufactures have these repeated problems, if they find one they fix it on the next production run and thats it, unlike aristo that keeps putting out defective product.. and it seems like the most issues are with aristo products,and all you have to is to search this forum and it will tell you that,, dont take it personal Mark,you replied to GREGS post in defence of aristo and i responded against there poor quality products, and until they fix them wright and learn how to talk to customers i will continue to do the same.. guess i struck a nerve with you han, truth HURTS sometimes.. 
oh well your young you'll ajust. HE HE JUST JOKING DONT GET YOUR PANTYS IN A BUNCH 
Nick....


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## Cougar Rock Rail (Jan 2, 2008)

Hi guys, 
I would like to add my $.02 to the discussion. First, regarding putting power through side rods, it's similar to putting power through axle bearings--a very bad idea. Putting power through bearings causes arching and eventually pitting and loss of conductivity. At low current it isn't such a problem, but modern locos with multiple motors pull horrendous current through them. Similarly, there would be arching/pitting between the moving parts of the siderods. Regarding the tapered axle assembly method, where Aristo went wrong was on the angle of the taper. If they would have used a Morse taper with a smaller (less steep) angle, it would be self locking and actually require very little to keep the wheel from turning on the shaft. In fact it would take considerable pressure to pull the wheel off the shaft with a self-locking taper. That is actually something they could still pretty easily fix since it just means a slightly different taper on the wheel bore and on the axle stub ends. 

Keith


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## Dougald (Jan 2, 2008)

Guys 

This is a matter of debate and opinion ... and you are free to express it ON THE SUBJECT. Let's end the name calling and personal attacks ... 

Regards ... Doug


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## vsmith (Jan 2, 2008)

This has been a known problem ever since Aristo introduced the "new and improved" driveblock a few years ago, its important to discuss and be aware of since it powers almost every steamer, including the not yet released C-16 and standard gauge Connie. So its something worth discussing, lest if there is some glitch like something coming out with loose drivers and the gnashing of teeth that will come with it.  

To me, the BIGGEST problem isnt in our discussion of it, its the dog-gone "thou shall speak no evil" attitude on the Aristo forum, the fact that Greg had to post here, says alot about how responsive Aristo can and has been in the past to concerns about product issues. /DesktopModules/NTForums/themes/mls/emoticons/pinch.gif 

What I would ike to know is, what are the fixes, proactive or otherwise, so if I buy one I know how to make it work right out of the box, just like us being Bachmann's Beta testers, if Aristo will not answer on their forum, its up to the modelers to figure out the fixes. Like those discussed here, so keep at it, its good to discuss problems, even if Lewis says there isnt one []


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## Curmudgeon (Jan 11, 2008)

This is part of the "patented" design by just that....design. 
The gearboxes only come apart at leats on diseasemals with screws in from the sides. 
If the wheels were part of the axles, you could not get to them. 
IF you super-lock-tite the wheels to the axles, you may need a torch to do normal maintenance. 
Walthers had a drive similar to this in the pre and just post-war years. 
Called "Polydrive". 
I have one. Or, I should say, the remains of one. 
The 0-6-0 in "0" scale has a totally new chassis. 
To work on it, if you didn't get every last gear meshed right, and the axles in the correct order, you would never get quartering to match up. 

To make up for that deficiency, they allow you to put the drivers on any way you can. 
They cannot be keyed.


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## Cougar Rock Rail (Jan 2, 2008)

TOC's reply reminded me of some other issues with the new gearbox design: heat transfer and difficulty in maintenance/greasing. Now I know they will claim they are 'lifetime lubricated', but what I've seen happen is that the heat from the motor transfers down the shaft to the gear end which then melts the grease which then runs in a pool to the bottom which then results in premature wear. In fact the very early versions had a plastic worm gear and the heat caused them to have a complete meltdown! I believe the worm gears are at least all brass now. The new Pacific design is actually better with one big motor at the back end and then a driveshaft connecting the rest. That way the heat is kept separate. I've noticed the latest ones are 'vented' with cutouts. If they would use a Buhler or Maxon motor instead of the Mitsubishi (or whatever they are), that would help too with both power consumption, longevity and heat transfer. 
So Vic, to answer your question about what can you do right out of the box? I guess the best you can do is put low strength locktite on the tapered connection, and possibly even shim the sloppier ones. As far as lubrication.../DesktopModules/NTForums/themes/mls/emoticons/whistling.gif good luck! There's a reason I'll never own an Aristo engine../DesktopModules/NTForums/themes/mls/emoticons/tongue.gif 

Keith


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## vsmith (Jan 2, 2008)

So far I've been using mostly the centercab bricks on my bashes, which like Dave points out, have to remove the wheels before you can crack it open, but at least I dont have to piddle with quartering the darn things.


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## Bill Swindell (Jan 2, 2008)

I have done some work on Aristo power trucks and have an idea (which may not be new). I don't believe that taper is the real problem. I think the real problem is that the pointed part of the taper on the shaft may be too long. It MUST be below the flat place in the wheel where the star washer seats. Otherwise, the screw will not hold the wheel tight to the axle.


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## Cougar Rock Rail (Jan 2, 2008)

The problem you describe, Bill, is definitely true of some of the tapers--I've seen that issue too. But if you machine a little off the shaft so the screw seats against the wheel then it goes out of gauge so you're left with the same issue of having to shim it up. As I said, in my opinion the simplest (and cheapest by far) fix for Aristo would be to change the taper angle so they are self locking like a Morse taper. I suppose they could put a roll pin in too, but they're probably reluctant to do that because it means that the rest of the drivetrain would have to be 'right'.  

Keith


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## Bill Swindell (Jan 2, 2008)

Shortening the end of the shaft will not change the gauge since the taper is unchanged. Adjusting the wheel gauge really is a pain with this design.


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## lownote (Jan 3, 2008)

As a newbie to this hobby I'm in some ways really impressed with aristo and in some ways pretty dismayed. Theyre' good on price--frankly, I'm just not willing or able to pay much more than what aristo charges. I'd love to get an Accucraft K4 but they're just out of the range I'm willing to pay. That's not meant as a complaint, it's just that it seems like Aristo is aiming at people like me, and they make some price compromises to get there. If the only things available were all $700 and up, I'd be doing some other hobby. 

So I expect some compromises to get the price down. The Prime mover power block seems great for diesels, but a little problematic for steam models. I noticed, even before mine fell, that some of the wheels could be turned on the axles without moving the gearbox. It seems like it'd be fairly easy to fix, but I'm not in manufacturing and don't want the price to go up any more. 

The train engineer thing is driving me nuts. The documentation is comically bad. The 75 mhz.system is very fragile in my experience and I'm ready to go to some other system, but on the other hand customer service and repair is very good with aristo. Then again, it would not have to be if the products had less problems. Ilike it that the President of the company answers my emails and posts on the forum


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## Mike Reilley (Jan 2, 2008)

This is a particularly good post for newbies to MLS. Greg and others have done a good job explaining why there are some operations issues with the Aristo steamers from the drive train design...and our newer members need to understand them. Further, as Lownote expresses above...there's a substantial cost difference between the Aristo and Accucraft engines...and THAT is important to a HUGE part of the membership here...and Greg explained one aspect of how Aristo was able to produce the Pacific at a lower price. The same could be said for the Bachmann K27 and an Accucraft K27...price makes a DIFFERENCE. 

Cost and performance are always a tradeoff...and I hope that we MORE threads like this. Even though the performance aspects were discussed in the past, I don't recall EVER reading an explanation that included cost as a parameter. 

Lastly...while us old timers here know this was discussed in the past...new folks don't. And given the difficulty one has finding any information using the search processes here (something I DEARLY wish were improved DRAMATICALLY)...I wouldn't expect newbies to have a level of MLS sophistication to be able to find anything of meaning with the search. 

I commend everyone on this post...we need MORE like it.


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## Guest (Apr 2, 2008)

Posted By Mike Reilley on 04/01/2008 8:16 PM
This is a particularly good post for newbies to MLS. Greg and others have done a good job explaining why there are some operations issues with the Aristo steamers from the drive train design...and our newer members need to understand them. Further, as Lownote expresses above...there's a substantial cost difference between the Aristo and Accucraft engines...and THAT is important to a HUGE part of the membership here...and Greg explained one aspect of how Aristo was able to produce the Pacific at a lower price. The same could be said for the Bachmann K27 and an Accucraft K27...price makes a DIFFERENCE. 
Cost and performance are always a tradeoff...and I hope that we MORE threads like this. Even though the performance aspects were discussed in the past, I don't recall EVER reading an explanation that included cost as a parameter. 
Lastly...while us old timers here know this was discussed in the past...new folks don't. And given the difficulty one has finding any information using the search processes here (something I DEARLY wish were improved DRAMATICALLY)...I wouldn't expect newbies to have a level of MLS sophistication to be able to find anything of meaning with the search. 
I commend everyone on this post...we need MORE like it.




THANK YOU....... could not have said it better myself


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## Greg Vocks (Jan 2, 2008)

I am not trying to stir the pot here (although I do love to cook); I really don't know the answer... 
How much is the Accucraft Pacific compared to the Aristocraft Pacific? 

I have Bachmann, a few Aristocraft, and some lower-end LGB. 
Would I love to have Accucraft, Aster, or some of the other higher priced locos? Sure. 

Reportedly someone once told Van Cliburn that they wished they could play the piano like he did, do which he replied "Do you want to bad enough to practice 10 hours a day?" 
You get out what you put in. That's why I don't have Accucraft or Aster (and why I don't play the piano like Van Cliburn.)


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## aceinspp (Jan 2, 2008)

As some have said this issue has been around for some time. Its good to get fresh input and Ideas. I know My Mike had one driver that always wanted to work loose from the day I got it. I solved the problem with a little better holding lock tight. Not the best answer but it did work. So after all the discussions from various folks here and on the AC forum how come they choose not to correct. I have had a issue with there so called new and improved smoke units. Ha what a joke and I have been harping to them for over 18 months with no improvements or reason why the things do not work. Anyway thats another topic of discussion some time. later RJD


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## markoles (Jan 2, 2008)

Greg, 

I have taken a step back and re read your first post again. 

I agree that technically, the modular gearbox design is a novel approach, and that the price of locomotives has stayed within the reach of many users is great. 

I think the ramifications of the design are improved performance of steam engine models and overall better running locomotives, steam and diesel, and MORE people getting involved with the hobby due to the lower cost of admission. The design that aristo has come up with is cost effective and works, within some given limits. The weak point is the attachment of the wheel to the axle. Some alternative methods (other than sending the unit back to Aristo for repair) have been to that has been suggested by you and others. With care given to paying attention to operation of the train, it is easy to get many hours out of these units before they require attention. 

I tend to overload my trains, just for the fun of seeing how many cars a given engine will pull. Unfortunately, I have more than once slipped driver #1 and the loctite just didn't handle it. Maybe I didn't tighten the screw enough. How many of those crappy chinese screws have you stripped? The heads seem to be prone to stripping. That's something Aristo should look at improving, as well. After the latest wheel slip - resulting in locking the side rods, I applied some red loctite and really tightened the screw. So far, that seems to be holding. Of course, that happened on the day of an open house, so it was kind of annoying. Luckily, Jim Miller had his E8s and aristo Mallet with him and we ran them no problem, all day. They were mixed in with other makers locos, but the longest and heaviest trains were handled by the aristo units, at lower amp draw. 

In thinking about this topic, I went to the MLS archives (you can get there by navigating to the main Public Forum, look for dwight's sticky at the top, then go to the old MLS and do a seach in Public Forum, Rolling Stock, or reviews and type in Mikado, and tons of posts pop up. Here's one example that you might have added on to, had there been a way to revive old posts: 

http://archive.mylargescale.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=16097&SearchTerms=mikado 

For the newbies: this design is a vast improvement over anything made previously in this price range. If you want power, these gearboxes are hard to beat. Greg has correctly pointed out the achilies heel of this system.


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## Greg Elmassian (Jan 3, 2008)

Thanks Mark for taking a step back. The wheel fitting issue has been one where it was a learning experience for many. 

I will submit though, I do not believe that the BIGGEST weak point is the wheel attachment, in the case of coming loose. You can fix this problem yourself easily, by removing the wheel, cleaning any loctite off the axle, wheel taper, lock washer and screw. You need to make sure the axle is not protruding through the wheel, so that the screw and lockwasher can be effective (a few swipes with a file fixes this). You can work the wheel around on the axle a bit, with a mild abrasive like toothpaste, to ensure you have a nice fit between the wheel and the axle. Once clean and the screw seats right, I have NEVER seen a driver get loose. (a little blue loctitie can be used on the screw, my opinion is that red is more than what is needed) 

But other problems, like the little finger in the metal clip that touches the spring to transmit power, and the rocking of the gearboxes longitudinally and poor back to back wheel gauge are problems that take a lot more effort to fix, and may be beyond most users. 

Here's my page on it: http://www.elmassian.com/index.php?option=com_content&view=article&id=215&Itemid=256 

I'm going through my Northern (bashed from 2 Pacifics) and am correcting these issues as I go. It's been fun really understanding how all this works. I started because I had smoke coming from a crankpin! 

Regards, Greg


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