# Aristo 4-6-2 problems



## Robbie Hanson (Jan 4, 2008)

So I ended up with a first gen Aristo 4-6-2 through some trading....

From time to time it runs smoothly, but it tends to run as though it has a serious bind in it somewhere, though side rods are fairly loose (still the plastic ones). Front gearbox may or may not be the issue. Tracks extremely poorly on LGB R3 (derails on any switch, forward or reverse, all wheels). It wobbles a LOT on straights (though with the front gearbox pivoting around the driveshaft, and the middle axle basically free floating about ten scale feet up and down, I'm not surprised). And the best part is that this was given to the guy from Aristo as a "repair" of a newer "Prime Mover" one.

Suggestions as to what I do with this dog? I've opened it once or twice and reseated the gears, which seems to help for a while, before they seat in or something and it returns to jerk-mobile status. It's a seriously strong puller, as it'll yank my Bachmann K-27 backwards(had to try). Power pickups are fine even with the older wheels. It even runs quietly--but I'm at my wit's end after six months with this. Any recommendations? I'm assuming Aristo doesn't want to touch it and frankly I'm not totally sure I'd trust them with it anyway.


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## W3NZL (Jan 2, 2008)

I have in years past rebuilt those things succesfully, but they still "weren't much"... These days the 
thing to do, would be to fit one of the new drive units to it... If Ur into kit-bashing like me, I got 3-4 
of them up in my junkplile that I cut pieces an parts from all the time...
Paul R...


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## Pete Thornton (Jan 2, 2008)

It wobbles a LOT on straights 
That sounds like the wheels are not properly seated on the axles - a wobbly wheel leads to wobbly running every time. 

I lost a few screws from my axle ends - the ones that hold the wheels to the axles. I'd check that your wheels are solidly fixed and at a true 90 degrees. Try to find some way to support the loco so the power can be applied and you can watch the wheels rotate while it is stationary. (Wooden blocks under the axles often work - or rolling wheels stands if you have some.)


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## George Schreyer (Jan 16, 2009)

Loose axle end screws will cause it to wobble every time, but there are other possible sources as well. 

Tighten all the axle screws first. Then flip it over and run it with clip leads to the pilot truck. The wheels should run true. If not, you need to figure out where the problem is. 

Run it at low speed to check for binding. The first place I'd look is to the universal joint. It runs off angle and is a natural bind point.


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## aceinspp (Jan 2, 2008)

You will also find that the wheels get dirty easily and cause poor running of the loco as you describe. Also look for any wires that may have shorted and burned if you have derailed the loco. You will have some wobble on the drivers but it should not be exstream. Worse case senerio as mentioned buy the newer power brick and install. Not to much of a project to do and there have been post of folks doing this. Later RJD


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## Michael Glavin (Jan 2, 2009)

Robbie, 

The screws that retain the driver to the axle halve is a common problem, note that when the drivers are removed the axles halves are machined in a square pattern where the driver engages the axle, if debris is present you'll not likely get them to seat squarely on the machined surfaces, wobbles will follow. So remove the driver completely and clean inside the driver and the axle halve. I replace the retaining screws with new phillips head or SHCS (allen head cap screws) with a dab of SMALL screw "Loctite” or similar thread locking adhesives. 

Also look closely at the axle halve-gear couplings when inside the gear box; they have been known to crack. Also note if there is play in axle halves and couplings, even though are pinned they still can wobble here. 

I suspect your back to back spacing is somewhat narrow, seems to be a common problem on the "OLDER" Pacific drives. It's can be issue to remedy this as the axles halves are pinned, thus eliminating the ability to easily correct the spacing. NoelW suggested its possible to space the drivers away from the machined square axle halve ends, to increase the back to back spacing, perhaps the appropriate sized washer or shim can be inserted into the driver’s squared female pocket. 

Can you explain “reseated the gears”? 

Michael


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## Robbie Hanson (Jan 4, 2008)

Pete: The wheels appear to be seated on the axles at 90 degrees--the screws ARE tight (that was my first thought, but nope). Wheels rotate (relatively) smoothly with little or no weight on them (the center axle prevents it from running well upside down). Front truck doesn't appear to sit evenly front to back, but tracks better than the rest of the engine. 

George: The wheels appear to run true. The universal joint may or may not be binding--I'm not sure how to tell with it together. The motor rests above the ashpan, between a plastic "firewall"(what else to call it?) in front and a second plastic "shim" on the back side. It seems like it can move around a lot, but taping it in with electrical tape just made it seem to run even worse. There's no side rod binding. 

aceinspp: The wheels aren't dirty enough to cause issues--I cleaned them with the Kadee wheel cleaner and they're as good as they're going to get. This thing'll run where an LGB 2-6-0 or my K-27 have issues. No wires have shorted--been there done that, I know to watch out. 
As to wobble from the drivers, the front gearbox rides ONLY on the driveshaft from the rear gearing. It tends to wobble to the side to the point of nearly twisting the inner wheel off the track on curves. It also "humps" up and down front to back--no idea where that'd be coming from, unless the wheels aren't perfectly round. Power block's out of the question for the moment--my experience with Prime Movers does NOT tempt me to acquire anything with them in the near or distant future. 

Michael: 
The screws are tight and the wheels appear to be solidly on the axles. I haven't taken them off yet, though. 

Axle halves aren't loose. 

Back to back spacing may be narrow, but so is the inner gauge on my (well-worn) LGB R3 switches. They don't appear to be rubbing on the inside guardrails. 

By reseating the gears I mean lifting the back axle out, aligning it with the front axle's gearbox, and placing it back in the frame. It makes the loco infinitely smoother for about two laps around my 8x15 foot oval before it returns to its former rough state.


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## Michael Glavin (Jan 2, 2009)

Robbie,

Have you been inside the front gearbox for a look see? 

FWIW: Every driver on an older Pacific drive I'm rebuilding was out of round some-what all required truing on a lathe. I indexed each axle halve to a driver, seated the drivers and chucked up each axle with driver and turned them round...

It sounds like your suggesting there is excessive play in the front gearbox, with regard to how it’s fixed or suspended in the motor block? I've seen many of these old drives and haven't noted any wear in this area to date; perhaps if you snug up the gear-boxes pivoting interference with the motor block it would create a little drag and stiffen up the suspension.

Is there notable play between the axle halves and brass washer/bearings? The early drives I’ve seen with some time on them wear a nice groove in the brass axle halve from carrying the weight of the loco predominantly because IMO the brass washer used to support the axles are poor excuses for bearings especially due to their narrow width with basically machines a grove in the axle. Most soft bearings have substantial surface area to support the loads. 
Pictured below is of a cut down Pacific drive I modified for an Atlantic, I’m rebuilding a Pacifc drive for a freind too. I fitted bearings to all axles and later did the same for the drive shaft. I also added a flywheel to the center of the motor block.



Michael


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## Robbie Hanson (Jan 4, 2008)

Michael, 

I haven't torn apart the front gearbox yet--I've been kindof scared to. Any small electrical components I should be concerned about? 

I'll check the wheels on a lathe--I work in the engineering machine shop at the school I go to and can try as early as Monday to see how the wheels run and, if necessary, turn them. 

if anything I'm suggesting that the front gearbox is too tight on the driveshaft--it seems to be rotating around it from lateral force on curves, lifting the inside wheel up. 

I'll check the axle bearings soon, when I have time--the next week or so is relatively rough, but then life should get a tad easier. I may end up doing your bearing modification--having torn apart a few mills and replaced dried up bearings, I definitely know the frictional difference between a dried up/friction bearing and a good roller or ball bearing. 

Thank you immensely for your help!


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## Greg Elmassian (Jan 3, 2008)

Michael, do you have any pictures of the stock gearbox opened? Have never seen the old style open. 

Thanks, Greg


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## Michael Glavin (Jan 2, 2009)

Greg, 

Yes, I can take some pictures of a stock original Pacific drive. As far as I know there are two early iterations one with brass axles and one with steel axles and then there is the current or new drive… 

I’ll post pictures later today, off to play in Hangar for a while. 

Michael


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## Greg Elmassian (Jan 3, 2008)

Yep, not interested in the new "prime mover" ones, just the way the older ones went together, and how the axles, gears etc were designed. 

Thanks! 

Greg


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## jgallaway81 (Jan 5, 2009)

The first line in the original post, he has a 1st gen pacific....

There are no prime mover components in the first generation pacifics. 
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## George Schreyer (Jan 16, 2009)

apparently, I never took any pics of the inside of the original Pacific block. As I recall, it is driven from the rear by a large motor canted upward into the firebox. There is a U-joint right off the motor. The other end of the U-joint drives a shaft going forward, geared to the 3rd and 1st axles. The center axle is driven from the rods. The rear axle is more or less fixed to the block, the other two are allowed a considerable amount of rocking motion. I do not recall what kind of bearings that this shaft rides in, but I don't think that they were ball bearings. 

Aristo has an exploded diagram posted at

http://www.aristocraft.com/techinfo/pdf/pacific.pdf


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## Greg Elmassian (Jan 3, 2008)

Hmm, the electrical pickup done with eyelets on the axles. 

Greg


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## noelw (Jan 2, 2008)

Posted By Greg Elmassian on 01 Jan 2011 11:45 AM 
Yep, not interested in the new "prime mover" ones, just the way the older ones went together, and how the axles, gears etc were designed. 

Thanks! 

Greg 
Greg... Really the org. designer is very good in a way that all drivers are equal presser to the track.. Like some good brass ho Eng's. The Center Driver is spring loaded and the front axle can swivel side to side for uneven track. This keep the motor block drivers even. Back driver are fixed due to the Bull gear to seat on the Warm gear. Only problem is, the darn brass bushing on the axles ware out and will slot the axle. This make the Eng. go sideways due to lone time running and waring on the axles. Then ends up with no side axle play..
Michael is instilling bearings , Not bushing again in mine and shave down the dr.wheel flange and tires. The other thing the darn Pacific first gen. is so under powered. So he is changing out the motor to. We are still work on the mounting of the motor.. One way might be, instead of end driver the block with a coupling, maybe go pulley/ belt drive and mount the motor back wards over the motor block.. Just have move the counter wt. and relocate maybe in two pc. 
One thing if it gets done the way we are going. It should last for ever and be one fanatic puller due to drivers are geared except the center axle kind of goes for the ride. 
Plastic side rods are not problem and will shim them up with brass tubing. Hope this help after Michael post a photo of the old dr. later guy.. Noel


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