China Drive Question

So as I move closer to getting some P48 gear together I was wondering if anyone out there is using Atlas O "China drive" equipped locomotives in scale switching type operations?  I see NWSL offers P48 wheelsets for my existing Atlas GP's which seems like an easy way to convert some locomotives rather than selling them and starting over.  Any opinions out there on this, can I get them to crawl?  I realize there is no substitute for the good old fashioned horizontal motor but $45 to convert vs. hundreds to buy new equipment seems like a no brainer?



Original Post

I have a number of them.  They are geared high for tinplate speeds.  Changing the gears is a bit technical, and requires heat and special tools.  And that’s assuming you can get the proper gear set.

The mis-conception is that motor orientation has something to do with it.  

Do what I do, and use China drives to pull trains round and round.  If you want high performance switching, send your Diesel to Jay.  That is his specialty.

Wiring in series cuts the voltage and speed in half at the motors.    The Atlas drives seem smoother than the Weaver or MTH.    I think they are not as smooth as a good single motor, but good enough for operations in most cases.   I think the Atlas gears and components are machined a little finer.    Also the mounting brackets have less play.

My suggestion is to get a set of axles and try it.   Like you say the price is so much better.   You could even try it on some regular wide O scale track to see how you like it.   

Nothing on my layout runs round and round, so all my stuff has to do some work, the through trains just a little.    I have some 2 motor  units from all 3 mfg that have done 2 rail.    Mostly because they were all that were available at the time at a reasonable price.    I don't recommend seeking them out but if you have some, give it a try.

Good advice above re wiring in series to slow things down. The only issue there is that if one truck loses traction it will spin up fast while the other one stops. You lose the "limited slip diff" kind of effect of having the motors wired in parallel. But worth the trade-off for me.

I have been experimenting to try and get the smoothest starting off and slow running on DCC. My observation is that the motors are the weakest link. There's a lot of end float in the motor shafts so when you first apply power, instead of the loco creeping forward, one or both of the motor shafts will climb up or pull down inside the motor and take up the slack before the loco jerks forward. And the motors seems to vary quite a bit so it's hard for the decoder back-EMF to manage the different loads.

The closest I've come to good starting and low running is by removing one motor. But you lose a lot of tractive effort this way so probably not worth it unless you run consists and don't have grades. Here's a clip of today's experiment with a single motor, I took the motor out of the front truck so it can free wheel. It's a Loksound Select HO with as much fine-tuning as I can do. You can hear how the decoder tries to manage the variable load of the cheap motor. I did try removing the flywheel which usually helps with starting off, but the slow running is worse as these motors cog badly without the flywheel. 

Here's a clip of a 3-unit consist all still with both motors in and Tsunami 1 decoders. Not such good starting and slow running control, but probably OK for mainline and long trains.

And for contrast, here's a clip showing the almost imperceptible starting off achievable with single motor drives without flywheels but with good quality decoders. The P&D F Unit has Pittman and Loksound Select L, the Red Caboose GP9 has a Maxon coreless motor and a Loksound Select HO decoder. Both have Finescale360 driveline upgrades. However, at any speeds higher than this, they shake, rattle and roll because of the chain drive. So I have a major upgrade coming from Jay C  which will finally deliver the performance I want under all condtions.   



Pete M

Frying decoders since 1994

Ed Kelly posted:

You can always rewire the motors and wire them in series instead of parallel.  This slows down the motors and should enhance low speed performance.  

DCC also seems to provide for better low speed performance.


They are badly engineered for slow running right from the start I think the term some of you blokes use is "Jack Rabbit".

I have 26 Atlas SW switchers which are designed for slow switching moves they have a single motor and the drive  is horizontal they keep me happy.

If you want the slow running for switching, the drive should be  designed for it not the Electrics, go to engineers like Jay C it would be worth the cost.

This has been talked about and thrashed out on all the O scale forums for years. Roo.




Photos (1)

I have a couple MTH diesels (2 railed)  with vertical motors.  With their factory electronics on DC  they were a little noisy but slow speed operation was great.  If I by passed the factory electronics and delivered DC directly to the motors, they ran too fast and jack rabbit starts, even with a good DC power pack.  They now are DCC and  they crawl so that you can barely see the wheels move. 

I have a 2008 Atlas F with vertical motors.  It ran pretty slow , quietly and smooth with just DC  and it runs as well as my Sunset FT with DCC.   And the Sunset FT is perfect.

So not all vertical mounts are the same and how they are powered makes all the difference in the world.   Both the Atlas and MTH I have encountered are engineered to run a couple life times, but I have found the MTH to be built with more slack in the parts and they are definitely noiser than my Atlas Fs.  

Good luck

John, remind me to name my son after you should I ever have a son! You seem to be the patron saint of P48 and I greatly thank you for all your help!

To all others, thanks for the awesome response, advice and great videos. Guess I will convert a couple of these and see where it leads.  Looks like a good decoder set for 128 speed steps may help as well as rewiring the motors.  The nice thing about the Atlas models is I can re-cycle my 3 rail stuff by 86'ing the current electronics, adding DCC and wheel pickups, rewiring the motors and changing out the wheelsets. I enjoy this type of tinkering PLUS I get to keep some old faves not to mention I am just an average guy making an average wage so laying out big $$ to get up and running isn't really in the cards.  

Happy Railroading!



I think most of us here are average guys on average wages sure I own 26 SW's but I went without a lot of other material things to get this far and I am now approaching 40 years in American DC O scale and half of what I have outlaid in money terms has been in shipping and custom's costs (fancy name for Govt Tax)

I like O scale and have stuck with it if you want something bad enough you find a way if you don't, you don't want it in the first place..

Use DCC you might find it suits your needs and your budget, good luck for the future.  

Roo in West Australia.

I cured DC "jackrabbit" starts in a 2 rail China drive Atlas F7 by pulling the bushing on the worm in the truck and polishing/opening it up a few thousandths. From the factory tolerances were way too tight. There was uneven wear on the worm where it runs on the bushing. I could also feel resistance spinning the flywheel by hand. Before polishing I did an experiment and simply removed the bushings....immediate improvement.

In DC the engine now starts rolling at 1.5-1.6v, before is was 2.2-2.4v and was not all.

To be honest, I don't know that those bushings are even needed, IMO you'll loose traction on the rail WAY before you generate enough torque to bend the motor shaft and/or damage the worm.

Add Reply

Likes (0)

OGR Publishing, Inc. PO Box 218, Hilliard, OH 43026 330-757-3020