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I had 4 of them on my layout for over 20 years.    The gearboxes still had good grease when I opened them.  

The gears are mostly delrin in the top of the gearbox.    No lube necessary.    on the lower part of truck, you can open the bottom of the truck/gearbox by removing the bottom plate.     There are 4 screws, one at each end and 2 on the sides.    They are screw into plastic, so handle them with a gentle touch.    When I replace them, I gently turn them the wrong way, until I feel/hear a slight click when the threads on the screw match up with those in the hole.   Then screw it in by hand gently.    Don't over tighten and I strongly recommend not using any kind of power tool.

I reccommend just a tiny drop of oil on each axle near the brass bearing inside the gearbox.    And some plastic friendly grease on the worm and axle gear if it appears to need it.   

Remember if you put too much in, it will just drip out on the track when it gets warm.    

Thanks ... and btw the F9 has been used after all.

I gained access to each gearbox as you mentioned, and there seemed to be plenty of red grease. So I put a drop of oil on each wheel bearing as you described and fastened the screws gently.

Should I remove the shell and do anything near the motor and linkages? One of the truck side frames came off when I was messing in the gearbox, but it went back on easy enough.

It is a very clean and new looking unit. Mainly because of the body shell. (UP 1475A)

And one last thing. This unit shakes a little bit when it goes through my turnouts. And oddly, if you go fast through the turnout, it does not seem as bad. My layout has Atlas code 148 track and Custom Line turnouts.

But a wheel set with gears gets 44 bucks at P & D, which is more than I paid for this Roco F9. So I guess I am NOT sure if I should get a new wheel set.

I think the Atlas Roco F9 and the cars they made in that era had flanges larger than NMRA recommendation.     They do bottom out on switch frogs and such if the switches and rail are a smaller gauge.

If the unit runs smoothly and pulls well for it (it is light so 10 easy rolling cars is good),  The axle gears should be OK.    Sometimes as they get very old, the gear on the axle splits and then spins loose and will not turn the axle.

NWSL sells replacement wheel sets with gears.    I thought they were more like 40-50 for a set of 4 but it has been a long time since I looked.    These would have smaller flanges and good gears.      I don't see a need unless you have a broken gear or really can't stand the behavior on switches.     P&D may stock the wheelsets too.      They are not the same as Weaver replacement axles, which I know P&D also stocks.

Mine ran for years very well.   I never added weight but I did detail the shells as close to an F7 as I could get for PRR.     I shaved off the handrails and added wire ones.    I removed the steam generator and replaced the pilot, and moved the front portal.    I replaced them when I got P&D F3 kits.  

Thanks all!

The Atlas Roco F9's are sometimes an amazing value on Ebay. I am not going to modify mine. Even the larger couplers work with more modern variations from Atlas.

So I am happy, but I would like to remove the body shell. So is this simple to do? I would like to apply light oil to some of the mechanisms there. This engine makes more noise than my brand new Atlas U-23B (which is almost silent).

The shell is held on with 2 tabs on each side of the fuel tank.     If you look at the tank, you will see a slot at each end of the fuel tank skirts.    These tabs are on the frame.     To remove the shell, you carefully spread the shell at the fuel tank skirts and slide it up.    Once the skirt is clear of the tabs, lift the rear higher and slide the shell forward over the front coupler.    You might have to get almost to 90 degrees to get over that big coupler. 

Thanks PRRJIM, about the shell.

BTW, I just bought another Atlas Roco F9. It was the Chesapeake and Ohio and is brand new. Go figure.

Since I have a small point to point layout (20' x 2'), I decided to use these Atlas Roco engines in lash ups only. I will not need other cars. If a engine's motor becomes hosed, I will just turn it into a dummy.


My old Atlas Roco F9's would bump through turnouts laid to NMRA spec flange ways.  The cause was that the flanges were slightly thicker than the guardrail clearance.   Back before NWSL offered replacement geared axels, several members of our DC Area O scale group addressed the issue by thinning the backside of the wheels.  Not owning lathes, we'd put the units's upside down in a cradle, apply power, and  hold a file on the back side of a wheel as it turned.  We'd, periodically check progress with a NMRA flange gauge.   Pretty crude but it worked.  We learned the trick from John Armstrong.  John later published an MR article on how to sure foot the units so that under load they wouldn't rock off the railhead.  John ran his A-B-A set (kitbashed B unit) in heavy service on his Canandaiguia Southern railroad for at least 25 years.  

Last edited by Keystoned Ed

Thanks Keystoned. I observed the engine closely as it moved through the turnout, and your explanation seems correct.

But, I must ask. How long does it take to complete the task of filing that you have mentioned. What kind of file is required. I assume not a needle file. I have standard files like you get at Home Depot, and I have a pack of needle files like you get at Hobby Lobby.

Another poster mentioned gauge. Perhaps the wheel sets need their gauge widened a few one thousands of an inch. Is there any method for doing that?

And can you just test the engine through the turnouts, instead of using the NMRA flange gauge.

You will need to buy a NMRA  Standards gauge.   Beyond the F9 flanges, it comes in handy to check wheel gauge, coupler height, and track gauge - particularly at turnouts and rail joints on curves.  

you'll want a relatively wide fine single cut file so it is easily controlled when held against the back of the turning wheel.  You don't have to thin the entire wheel - just the flange  will do.  The Atlas/Roco wheel materal is relatively soft and the process  doesn't take too long if you have a sharp fine cut file (grain of the file running in only one direction).  Get one about 3/4" wide and  6" long or larger.  Invest in a good brand like Nicholson - cheap metal cutting tools don't last.  By checking progress with the NMRA gauge you can get a  fairly well matched set of flanges that will pass smoothly through through turnouts. As you get into the project you'll develop a feel as to how fast the locomotive should be running and how much pressure to apply with the file.  The good news is that the cost of this fix is minimal, and if you mess up, you always have the fallback option of replacing the wheels with NWSL geared axels.

Last edited by Keystoned Ed

All of my many Atlas Locomotives from the 1970's eventually developed split axle gears. When I acquire additonal locomotives, I routinely change the axle gears with NWSL replacements and that tales care of the problem. I ordered a whole bag of those gears. Additionally these units often resonate through their shells when running making a "grating" sound. I solved that problem by drilling and taping a small screw through the shell into the fuel tank.  I still have my original F-9 in operation which I purchased at a hobby shop in Brooklyn,NY in 1970 or 71 when Atlas first brought the sets out. They were universally "bad mouthed" by the old guard O gaugers but , amazingly, they encouraged many train folks to try 2-rail O!

Thanks to all for the advice. I am very new to the hobby.  So, I know nothing.

But the first issue I had to address was a busted side frame mounting boss. When I received my first F9, I knocked the truck side frame from the truck, with the slightest of touch. The seller did not mention that in his E-bay listing.

Then, I found the 2003 Nov-Dec issue of O Scale Trains online. This publication had an article that discussed using an Atlas/Roco F9 to make a GP-9. The article gave instructions to repair a broken side frame mounting boss.

This part is now fixed, but in the process I had to remove the wheels from the affected truck. Now the engine runs well and looks good, but in reverse it sounds like a helicopter engine. So, back to the drawing board

Sideframe Mounting Boss


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  • Sideframe Mounting Boss

Today I tried to fix the noise of the F9 loco in reverse.  I checked. the rear truck and nothing noteworthy there, just lots of grease. Then I took the body shell off and loosened the screws holding the motor in place. Then I thumped to loco on the work bench several times and tightened the screws. During testing, I concluded the reverse noise was much reduced.

My brand new in box F9 has departed Phoenix today, so I may have it by tomorrow. For every Atlas U23B, I can have 4-5 of these Atlas/Roco F9s.

Thumping any kind of model seems like NOT a good idea to me!    However, it used to work with old Tube style TVs.

My guess is that one or more Axle gears may be split.     PUt the loco in a cradle upside down and hook leads to it.   run it slowly and see if one truck or the other jerks every revolution.     Another the would be to put you finger on a wheelset to see if you can stop it.    The one you can stop pretty easily with your finger has a broken gear.

Thanks all. Check! Do NOT thump Atlas locos.

My most recently purchased F9 was not delivered today. It went to FedEx Smart Post instead. Not smart.

And I did check each gear. They all look fine. The motor and all of its drive linkages perhaps contribute to unwanted noise. It is not that bad but the engine does make more noise (in both directions) than my Atlas U23B purchased earlier this year.

So, I decided to hit the wheel sets of the F9 with a wire brush. Only problem was, the flex coupling on my Dremel tool has disintegrated. I ordered another one, but it originated from Florida. Thank goodness the shipping was free.

When the coupling arrives, I will buff each wheel front and back, because they do look messed up. They have not been blackened. They just have 40 years of goo on them.



So will using a file on the wheels remove the plating as well? just wondering because someone mentioned using a file on the backside of the wheel flanges.

Also, in the article from O Scale Trains they were using a wire brush to remove the blackening on the wheel tread. So does a wire brush just remove the blackening material, but leaves the plating in place?

Last edited by Stwa

I was really hoping I could remove material from the original wheel sets, so that traversing a turnout would not cause an issue. I would rather not purchase NWSL replacement wheel sets.

The article in O Scale trains recommends using the NWSL wheel sets and the author's prefer the .172 rather than the .145 wheel set. The dimensions refer the width of the wheels. Any comments?

I have provided an attachment where the authors explain using a wire brush. Now these are Dremel wire brushes. Me thinks they will be ok to use on card board much less plated steel. Am I wrong? I was also thinking I might use a stone grinding tool on the back of the wheel flanges since I might have to go just a few thousands of an inch.

NWSL Wheel Sets




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  • NWSL Wheel Sets
Last edited by Stwa

So, my brand new in box Roco F9 arrived last week. The seller lied, it was hardly brand new, but we worked out an alternate deal.

Then I took off a few wheel sets, and I thought I would mention, most of the wheel sets are already pitted, have rough areas, and plenty of other discolorations and flaws. The flex coupling for my Dremel arrived the day before Xmas, so I spent Xmas day using the wire brush on the wheels and many of the blemishes and discolorations were removed.

I did not buy an O track gauge thingy because Micro Mark wanted 24 bucks & shipping for one. After I buffed each wheel set, I would just roll it through some turnouts as a test. The wheel sets would go through half of my turnouts without problems. 

Plated wheels are actually problematic.  They are ok for a while, then the plating wears off.  We have found that traction improves with the plating gone.

But then you have corrosion control - keep them coated once you have bare steel.

The blue/black steel wheels are not plated.  That is either gun- blue or " Parkerized".  It, too, will wear off the treads rapidly.  These are generally the preferred O Scale wheels.

Plating is done so the steel will survive the trip over the salty Pacific Ocean, usually.  I don't know why the older Atlas/AHM models were plated.

Try the file trick - a brand-new Nicholson will be best.  The grind stone will get grit in all your bearings, resulting in premature bearing failure.  Keep the filings away from the motor.

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