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@PRR Man posted:

Jim; most vertical drive motors have 'double lead' worms on them. (which you probably know) Changing to a single lead worm effectively reduces the ratio by doubling it, Some time ago I bought that spec worm and worm gear set from NWSL to experiment with. It works! Toughest part was getting the OEM worm off the motor shaft!



Hi Chris,

Can you supply a link or part number to this NWSL worm gear set?  This would be great if I could run my Atlas units back to parallel wiring and get good speed control.  What do you believe makes it so tough to get off of the motor shaft, e.g. do you think they used some type of Loctite or is it just some crazy-tight interference press fit?

Thanks.

Scott

While I've already commented on the top three items on my wish list to start operating in 2R if I'm looking at locomotives specific to true 2 rail it would be:

  1. CNJ Atlantic Camelback 592
  2. CNJ Pacific 831-835 with the correct Wooten firebox
  3. PRR K2 Pacific

I'd do a second list on passenger cars and a third on freight cars, but I have more than a lifetime of projects already for the ones on my wish list.  That was the gist of my original posting to this thread.

I'm sure I'm in the minority, but I want 2R steam with WowSound decoders and smoke units installed from the factory.

  • Erie K5 Pacific is at the top for me
  • Erie Heavy Mikado
  • EMD SW1 (Erie, EL, B&O, and Chessie)

What would I settle for? Any Erie, PRR, or B&O smaller steam. Also, diesel switchers from 25T up through MPs with LokSound decoders.

This msg is intended for everyone who wants to expand two-rail modeling, and that includes me.  For every one of you who "hates" the "China Drive", be aware that elimination of a "China Drive" on a diesel of any size would probably reduce the number of modelers who model in two rail "by about half", since a tower drive cannot accommodate the same minimum curve radius that two vertical and separate motors provide, and a smaller curve radius is almost mandatory for many two rail layouts due to space considerations.  The only advantage of a tower drive that I am aware of is that it permits a fully detailed cab. I am not aware that there are ANY advantages to the use of a tower drive on a diesel other than what I identified above.  For steam guys, this discussion is moot.  My opinion.

@Hudson5432 posted:

....For every one of you who "hates" the "China Drive", be aware that elimination of a "China Drive" on a diesel of any size would probably reduce the number of modelers who model in two rail "by about half", since a tower drive cannot accommodate the same minimum curve radius that two vertical and separate motors provide, and a smaller curve radius is almost mandatory for many two rail layouts due to space considerations.  The only advantage of a tower drive that I am aware of is that it permits a fully detailed cab. I am not aware that there are ANY advantages to the use of a tower drive on a diesel other than what I identified above.  For steam guys, this discussion is moot.  My opinion.

Sorry but in my opinion your post seems like pure speculation, and you do say "probably". The huge advantage of a single motor tower drive over twin motors is smoothness of drive at crawling speeds; pretty essential for a smaller layout with emphasis on switching.

My Weaver Geeps with tower drive take 36" radius curves just fine, as does my Red Caboose GP9 (early Atlas/Roco tower drive) and my Atlas SW1200RS, with central motor etc.

Does this issue arise in HO & N Scales? As far as I know, all diesel locos in those scales are central motor/tower drive, and in HO they take 18" curves ok, even if it's usually in hidden staging. Minimum radius is just a non-issue.

Honestly, some of the fretting that goes on in American O - both 2- & 3-rail - anyone would think that smaller scales had never been invented or run successfully!!!

Last edited by SundayShunter

The funny part is I just received a MTH 2 rail NH GP9 from the last run by the current owner.  It has the latest MTH DCC decoder software and I was amazed that even with the so-called China drive, it creeps perfectly starting at one speed step and and is extremely smooth. I have used it for yard switching and it is at least as good as the Atlas switcher and far superior to the Weaver single motor drives.  So maybe the issue is not a single cause but relates to DCC decoder software, motor quality and drive components.  I rate the Pittman motor in the Weaver model as the best motor but the other variables do play a part such as plastic chain and cheap gears in the Weaver model (and no they aren't cracked which is common). 

Just saying that there are several variables and common issues with some early DCC decoder's software.

Yes, my post does contain speculation, since I do not know how many operators of smaller scale layouts with relatively sharp curves use diesels.  My comments regarding the ability of a two rail "China drive" locomotive to negotiate a sharper curve than a single motor locomotive with universal joints is not speculation, it is fact based on the engineering mechanics of the driveline.  Design guides for universal joints state that, for non-slip joints, the max misalignment of a universal should be limited to ten degrees or less to avoid vibration and generally poor performance..  For a vertical motor not connected to another vertical motor, the rotational misalignment can be "just about anything you want" and whatever the flanges and track will permit.  I am still wondering why the two vertical motor arrangement is called a "China drive".  My understanding is that it was first used by Lionel, and is thus afflicted with the "cannot operate at low speed" claim?

As for the ability of a locomotive to operate smoothly at a very low speed, it does depend on the motor and the driveline, and also the control system used.  I have heard that the models of the MTH 44 ton locomotive have a carbody hood width that is prototypical, and that previous and more expensive models of this locomotive required wider hoods due to the power arrangement.  I do know that MTH locomotives will operate at a minimum speed of 3 smph, and run-in locomotives will operate at 2 smph using the MTH DCS system.  I suspect that any DCC system can do as well.  I have switchers with a single motor and a chain drive, and their low speed performance isn't even close, although these engines have no electronics.

Bottom line, their is a much greater chance that 2 rail scale will survive and perhaps even expand if a major player's products are also available.  If that doesn't happen, we will be as limited with regard to motive power as we are now to track and turnouts.  Again, my opinion.

Hudson5432, my layout has 2 areas where the radii is 36”.  While I mainly run steam, largest being a large SP 2-8-0 I do have a number of Diesel engines. A GP 10, a CF 7, a BL2, a couple of SW 1s and a Whitcomb switcher. All are 4 axle and will easily handle the 36" radii.  I’d guess a 6 axle unit might have trouble.  My layout is posted in the 2 rail layout video thread.

Peter

@Hudson5432 posted:

Yes, my post does contain speculation, since I do not know how many operators of smaller scale layouts with relatively sharp curves use diesels.  My comments regarding the ability of a two rail "China drive" locomotive to negotiate a sharper curve than a single motor locomotive with universal joints is not speculation, it is fact based on the engineering mechanics of the driveline.  Design guides for universal joints state that, for non-slip joints, the max misalignment of a universal should be limited to ten degrees or less to avoid vibration and generally poor performance..  For a vertical motor not connected to another vertical motor, the rotational misalignment can be "just about anything you want" and whatever the flanges and track will permit.  I am still wondering why the two vertical motor arrangement is called a "China drive".  My understanding is that it was first used by Lionel, and is thus afflicted with the "cannot operate at low speed" claim?

As for the ability of a locomotive to operate smoothly at a very low speed, it does depend on the motor and the driveline, and also the control system used.  I have heard that the models of the MTH 44 ton locomotive have a carbody hood width that is prototypical, and that previous and more expensive models of this locomotive required wider hoods due to the power arrangement.  I do know that MTH locomotives will operate at a minimum speed of 3 smph, and run-in locomotives will operate at 2 smph using the MTH DCS system.  I suspect that any DCC system can do as well.  I have switchers with a single motor and a chain drive, and their low speed performance isn't even close, although these engines have no electronics.

Bottom line, their is a much greater chance that 2 rail scale will survive and perhaps even expand if a major player's products are also available.  If that doesn't happen, we will be as limited with regard to motive power as we are now to track and turnouts.  Again, my opinion.

Yes China-drives will take silly-radius 3-rail curves, I grant that, but the generally accepted minimum radius in 2-rail is 36", and tower drives will take that quite easily, at least with 4-axle diesels. My 6-axle Atlas SD40 also can take 36" radius, but it's a China drive, I don't have experience of 6-axle tower drives, but I suspect that if space is tight (my layout is 17ft x 8ft) the owner won't be looking to use huge engines anyway.

Where I do agree with you totally is that there needs to be a major manufacturer of decent 2-rail stuff at sensible prices.

@Hudson5432 posted:

Yes, my post does contain speculation, since I do not know how many operators of smaller scale layouts with relatively sharp curves use diesels.  My comments regarding the ability of a two rail "China drive" locomotive to negotiate a sharper curve than a single motor locomotive with universal joints is not speculation, it is fact based on the engineering mechanics of the driveline.  Design guides for universal joints state that, for non-slip joints, the max misalignment of a universal should be limited to ten degrees or less to avoid vibration and generally poor performance..  For a vertical motor not connected to another vertical motor, the rotational misalignment can be "just about anything you want" and whatever the flanges and track will permit.  I am still wondering why the two vertical motor arrangement is called a "China drive".  My understanding is that it was first used by Lionel, and is thus afflicted with the "cannot operate at low speed" claim?

As for the ability of a locomotive to operate smoothly at a very low speed, it does depend on the motor and the driveline, and also the control system used.  I have heard that the models of the MTH 44 ton locomotive have a carbody hood width that is prototypical, and that previous and more expensive models of this locomotive required wider hoods due to the power arrangement.  I do know that MTH locomotives will operate at a minimum speed of 3 smph, and run-in locomotives will operate at 2 smph using the MTH DCS system.  I suspect that any DCC system can do as well.  I have switchers with a single motor and a chain drive, and their low speed performance isn't even close, although these engines have no electronics.

Bottom line, their is a much greater chance that 2 rail scale will survive and perhaps even expand if a major player's products are also available.  If that doesn't happen, we will be as limited with regard to motive power as we are now to track and turnouts.  Again, my opinion.

I think the big complaint with the 'China Drive' is not so much the slow speed performance but the jack rabbit start from 0 to 2 MPH mostly caused by the slot car gearing of the drives.  In my experience China Drives run at around 200 Scale MPH.  With a more favorable gear ratio you will see the start up performance improve.  Perhaps someone like Atlas will get the message to offer an optional gear set (extra purchase, but "screwdriver bolt in") with a 20:1 or 25:1 ratio over the 10:1 ratio currently supplied.   I attempted to work with NWSL's previous owner on a scheme to do this but he had no real interest and wanted $22,000 to begin looking at the problem.  

'Can you supply a link or part number to this NWSL worm gear set?'

Scott, after a long technical conversation via email with NWSL (this was years ago), they suggested their set for the G scale 'Delton Doozie' would do the job. Their part # is 2119-6. It contains the worm and axle worm gear. The worm is a single lead.

Getting the OEM worm off the motor shaft was a major undertaking. I tried a gear/wheel puller. Nope. Then heat. No good either. I was very concerned about ruining the motor with too much effort or heat. I finally used a cutting wheel to slice the worm lengthwise.

The axle gear was a perfect friction fit. The worm needed Loctite to stay on the shaft snugly. The operational result was pleasing. However I declined to do  three more trucks for the A-A set I was working on.

I believe the worm is highly heated at the factory, then press fit onto the motor shaft. You'd be best to start with a motor without a worm installed.

I'm with Jim. We have been asking for single lead worm vertical drives for years. It's one small change that has a significant impact.



As an aside. I've changed most of my road units to vertical drives. They last longer at the club for open house running, which lasts hours. With proper lubrication, truck/frame interface mount mods, and decoder adjustment. I get very good starts and slow speed operation.

Last edited by PRR Man
@PRR Man posted:
I believe the worm is highly heated at the factory, then press fit onto the motor shaft. You'd be best to start with a motor without a worm installed.

They probably 'sweat' the gears on with inductive heating.  You can actually build one yourself if you are handy with electronics.

A couple of how-to links:

https://www.instructables.com/DIY-Induction-Heater/

Ebay also has a ready to go unit for about $200

https://www.ebay.com/itm/Mini-...3:g:ZzUAAOSwokNgM1eB

Last edited by Jim Scorse

I wouldn’t mind either “dummy” steam locomotives In 1:48 like the armor guys have in 1:35 or smaller-flanged “Dummy” wheelsets for us narrow-gaugers to convert something like a Lionel/K-Line 0-4-0 into a static locomotive to represent the broad gauge.

i fear that idea wouldn’t appeal to the designers who put up their stuff on what I call “Haystack Central” 3-D market place.

Thanks Chris and Jim.  That info was very helpful.  Let me see if I can find a junker Atlas motor or powered unit and play around with it to start.  I have a very fine point Oxy/Propane jewelers torch (the torch nozzle orifice is so small that it needs to be drilled in a ruby with a laser since drills don't go down to that small) so it can produce a very fine concentrated flame that I can try.  Obviously have to watch and not overheat and distort the motor shaft.  I also have a 13 x 30 lathe that I can potentially either hold the motor rotor in my smaller 5" 6-jaw Set True chuck or, if small enough, use a 5C collet (may have to bore out an emergency collet if the rotor comes out to be an odd size).  Then I can just gently turn down the old gear with a real sharp high speed steel tool in the lathe and slip on the new one with some Loctite 603, if it is not a press fit.

Jim,

Thanks for the links.  I am familiar with the induction heating units as they use those in CNC machine shrink-fit style end mill holders since these holders produce very little runout.

Thanks again for taking the time to look up that info.

Scott

I have replaced a number of the MTH gears - they actually fail at the ten year point if you run continuously (like in a museum).

It takes two special steel plates with milled space to go between the worm and motor, bolted together for no chance at slippage, and torch heat.

Also, when you tap the shaft, you need a rag to catch the motor as it falls - motors hate shocks.

Still searching for a really good set of Dalman trucks that don't cost a fortune (or at least more than the car they support).

Bob, you might recall my Dalman 2-level truck project of a very long time ago; I slipped off the radar following heart surgery and marriage break-up that knocked me around quite a bit.  Well, having beaten the odds and escaped the ex-wife's constant disapproval of my modeling, I am working on finishing that truck at long last!

My wish-list for O-scale in order of preference:
1 - A USRA Light Mike made with injection-moulded styrene, so that we can chop and mod and upgrade to our hearts' content.

2 - Core kits for heavyweight cars, or at least inj-mlded roofs.  I can scratch streamliner roofs without too much effort but clerestory roofs are a complete pain in the rear.

3 - A USRA 0-8-0 switcher made in the same way as the light mike.

@Tom D. posted:

Couldn’t the early Weaver engines take pretty tight curves?  The 2 and 3 rail drives were identical.

The older Weaver, Red Caboose Geep  and the Austrian Roco-Atlas F9 will all run on the original Atlas 24"R track. Of course, the F was designed for that radius, and the Geep has pretty much the same chassis. The only "modification" I had to do was to not completely tighten the coupler box screw, to allow it to pivot slightly. Having said that, I suspect they are much happier on the wider curves I'm now using!  🙂

Mark in Oregon

1. Kadee offer a variety of trucks...freight and passenger...in keeping with their quality of the same in HO and large scale.

2. Aftermarket roof walks for 40' and 50' boxcars...et alia...that are see-through, prototypical to various steel/grid styles used up to the time they were ruled out by the FRA.  Like the ones on premium cars by Atlas, MTH, Lionel, Intermountain, to name a few.   Most of our (1:48) train viewing is bird/drone/plane vantage.  Rolling stock, even-or-especially the crummiest, most weathered, graffiti'd, or derelict of all, deserves this bit of celebratory respect!  (IMHO, of course)

3. Extruded plastic (Styrene or ABS) code rail molded in a 'rust' color with which to add track guard rails on bridges and trestles, be cut to 39' lengths for stationary or MOW rolling stock rail racks, to lie in l-o-n-g lengths along existing right-of-way in mock anticipation of installation by the MOW crew, to be made into welded-rail bumpers that don't short circuit sidings, to be easily fashioned into dummy turnouts to justify that permanently-parked rolling stock on the siding (ala, Roadside America layout, et al.), ....etc., etc., etc..

--------------------

I can't help myself...these additional two are bunched too close to "the top 3 items"...

4. A variety of scale, operating, lighted wig-wag crossing signals as were so popular throughout this country, more so within the haunts of certain flags.

5. Serious focus on 'Dead Rail'...All areas...from components, packaging, installations, DIY's, to encouragement and intellectual/emotional support.   It will be very embarrassing to have this concept take firm root and find lasting success in the HO branch of the hobby before the next logical application...O scale...has led in its further development.  (again....IMHO, of course)

Break time....'nuf said.

KD

Last edited by dkdkrd

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