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Almost all the steam and diesel power in my Run Room is MTH.  The performance of the MTH engines with Proto-Scale 3-2T 3-Rail/2-Rail Conversion capibilities is unacceptable and I won't be buying those engines.

 

After running my "new" #20-3383-1 (engineering edition) I discovered it will not creap through my Ross switches (Ross 220 #8 switch and Ross 101  11 degree switch).  I must run it through fast like I used to run my postwar engines (so I could blow the whistle).

 

Thorough investigation showed that the wipers on the engine rear axle are very fragile, and all wheels are insulated from the engine and tender housings causing a problem with conductivity with the outside rails.  The engine has only 3 wheels wired to act as common to the outside rails and one of those wheels has a rubber tire.

 

After extensive improvements to my 20-3383-1  2-3-1 Pacific Steam Engine, the engine is on probation.  See solutions here  MTH 20-3383-1 2-3-1 Pacific Steam Engine or  http://www.slsprr.net/features...0Pacific%20Steam.htm

Last edited by Susan Deats
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MTH 3/2 steam locomotives are set up like 2-rail locomotives (they kinda have to be to work in 2-rail. Basically, the wheelsets are all fully insulated. What's happening is you're losing your ground. The way around that on turnouts is to put a connection to common on the closure rails of your turnouts, especially larger ones, but to prevent shorting from the pickup rollers, these connections will have to be tied to a relay (or Tortoise motor contacts.) We had to do that on a #8 curved turnout. Not really hard to do.

 

What kind of turnout motors are you using?

Originally Posted by gftiv:

Why should the 3 railers have to rework their layout to accommodate the 2R/3R engines?

Most of us probably don't - for example I use only Fastrack switches even though I otherwise have all Atlas track - so I don't have these or any other problems sense they are bulletproof switches. 

 

So, I don't have the specific problem Susan Deats has but I had problems with them.  have noticed that MTH 2R/3R engines seem to be weak on picking up power from the outer rails as compared to toy loco made only for 3R.  I've had trouble with them quickly and firmly operating some block activated accessories, etc.  although so far they have activated the switches' auto-reversing features well enough. 

Almost all the steam and diesel power in my Run Room is MTH.  The performance of the MTH engines with Proto-Scale 3-2T 3-Rail/2-Rail Conversion capibilities is unacceptable and I won't be buying those engines.

 

Even some of the straight 3 rail engines will stall on a Ross #8 switch(a thing of beauty) without special wiring as alluded to. However I certainly agree  you.

 

We're not buying  anymore either. Why would you put wipers on a 3 rail engine to pick up the common, Rail-king seems a better deal to me.

 

I don't think turning a set of wheels around in the  tender would help much??

 

I don't have a engine and continuity meter handy.

gunrunnerjohn, there are 12 insulated wheels on my steam engine.  I didn't pull the wheels and I made some ASSumptions. 

 

The wipers on the rear axle are wired to the common bundle (I assume that is in contact with one rear wheel).

 

The driver wheels (one has a rubber tire) on one side appear to have wired contacts to wheel hubs that connect to the common bundle.  The front 4 wheels have no way to connect to the common wire.  I have no idea how the engine picks up positive and negative power when running on 2 rail.  One contact is obviously the common wire bundle.  There is no electrical contact/ground to the engine housing.

 

See instruction sheet page 9 for photo of wheels

http://mthtrains.com/sites/def...ction/20st15359i.pdf

I'd say add brass wipers and flex wire to the engines lead, trailing and drive wheels to better accomodate the ground p/u needs...attach all those to the main chassis via a single or mutiple leads- the removable center p/u should be well insulated and be fine on its own.

I always wondered how well a convertible engine...2r/3r...would adapt between venues...seems my question is answered.

I just saw some fine flex wire the other day and am struggling to remember just where that was, but there's other wire options too so long as you keep it thin and very flexible to keep lead and trailing truck binding at bay because of the added wire.

Originally Posted by gftiv:

Why should the 3 railers have to rework their layout to accommodate the 2R/3R engines?

You have to rework your layout so that all of the engines you choose to run on it work. I had to re-wire the Ross #8 curved turnout because short-wheelbase 3-rail engines or those with only two pickup rollers closely spaced (Atlas SW's, early Lionel Geeps, early MTH Geeps, small Box Cabs, etc.) would stall at low speed and lose their ground connections.

 

At some point in time, you'll have to rework something on your infrastructure to support a new purchase, even if you don't come anywhere near a 3/2 locomotive.

 

Clem:

 

I think the diesels are wired differently from steam and use double-insulated wheelsets. Steam gets complicated because there are so many moving parts that may directly or indirectly contact the locomotive frame, even if you double-insulated the wheelsets.

Originally Posted by AGHRMatt:
Originally Posted by gftiv:

Why should the 3 railers have to rework their layout to accommodate the 2R/3R engines?

You have to rework your layout so that all of the engines you choose to run on it work. I had to re-wire the Ross *3 curved turnout because short-wheelbase 3-rail engines or those with only two pickup rollers closely spaced (Atlas SW's, early Lionel Geeps, early MTH Geeps, small Box Cabs, etc.) would stall at low speed and lose their ground connections.

 

At some point in time, you'll have to rework something on your infrastructure to support a new purchase, even if you don't come anywhere near a 3/2 locomotive.

 

Clem:

 

I think the diesels are wired differently from steam and use double-insulated wheelsets. Steam gets complicated because there are so many moving parts that may directly or indirectly contact the locomotive frame, even if you double-insulated the wheelsets.

Hi Matt

Your probably correct. My thinking was with three axles the center wheels sometimes don't touch the rails and a traction tire on one wheel only leaves one wheel for contact. Just a thought.

Oh by the way I could use three rail wheelset's.

Clem  

I only have one 3/2 steam engine. PS&N Russian decapod.  Just some information about how it is assemble to achieve the 3/2 configuration.   Keep in mind three rail allows for common from both outside rails. 
Locomotive is split down the middle each left wheel is electrically isolated from the right wheel including the pilot. All left wheels are common and show continuity through to the frame.  All right wheels are isolated. 

The tender is designed for two rail pickup with the (4) axles as pickup.  (2) Axles, front truck, are power right rail. The front axles are isolated from the frame with plastic inserts in both side frames. The (2) axles, rear truck, are common left rail with the right wheels isolated. One of the truck side frames has brass inserts for the axle. Common pick-up through the truck frame and the frame of the tender.
Three rail pick-up center rail is via the two installed third rail pick ups.  A wiper assembly was add to the front tender truck to increase outside rail pickup via the other rail.  A couple of pictures.
Rear tender truck notice the brass inserts in the truck side frame. the wheels, bottom of the picture, are isolated from the axle.   Common pick-up (left) (Two rail).

The front tender truck is designed, (two rail), for pick up of power on the (right) rail. The isolated wipers are added to allow for Common pick-up via the (right) rail when the third rail pick-ups are added. Therefore you have Common from either the left or right outside rail.  
Noted difference front truck is the axle wipers and the plastic axle bearings.
Plastic axle bearings are both sides isolating the axle from the truck frame.

Remove the thirdrail pick-ups, leave the wiper, switch the three/two rail switch and it should be ready for two rail operation.

The wiper assembly on this axle appears to allow for common pick-up from both outside rails when the third rail pick-ups are added. Tender switch in the three rail position.

The Tender if all wheel/axles are assembled properly with the wipers should allow for common pick-up off both outside rails.  Locomotive only allows for one side common rail pick-up. 

 

Susan should check the tender for the brass insert bearings that allows for the two outside rail pick-up as it moves through a switch.  If all axles are have plastic bearings the only outside rail pick-up is via the wipers shown.  Limited outside rail pick-up as she indicated.   I could be wrong and often. 

 

Best wishes with your project.

Mike.    

Last edited by Mike CT
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