Which Turnouts are the "most friendly" for 2 Rail Wheelsets

This is my personal opinion so keep that in mind as others may have different opinions.

While a few different turnouts may allow scale wheels to physically function over them, I personally don't know of any that do so in a way that meets my standards. I don't like seeing a wheel dip into the frog before being picked back up even though it may stay on track and not derail. I also don't like any switches that will do it but with the caveat that you not try to back up over it.

Can a switch be made to run both wheels reliably without looking a bit goofy in the process? Yes but no one makes one. I have a couple but I built them. If you decide to use wheels swapped into existing trucks such as those from Northwest Shortline, you can use the .172" profile wheels and the gauge them a bit narrower than NMRA standards and they'll work pretty well across 3 rail switches. This really is the only true compromise way to do things but no one does it this way. The wheels are an improvement in the looks department than 3 rail wheels but still wide. .145" profile is the standard but even then it's .115" that is truly scale. P:48 uses these. You'd better have some very good scale track work to run them. Even if you were to do this, MTH scale wheel engines I believe are or are very close to the .145" width wheels so that doesn't help them too much.

Again this is all my personal opinion.

The reason why 2 rail wheels will derail on your turnouts has to do with the back to back spacing of the guardrails. They are too close together to prevent your wheels from picking the frog point. You might get lucky or you might not. If we regauge these guardrails then we have the problem that the back to back spacing on 3R wheels is too close together and they ride up over the rails and will usually derail. Best case scenario is that they just look really stupid in the process.

So the other option would seem to regauge 2 rail wheels so their back to back spacing is close enough that the guardrails can prevent the wheel from picking the frog. Now they are too close together and may fall in between the rails. The compromise is to run the .172" wheel profile. It's nicer looking than 3 rail wheels but not as nice as narrower wheels and still doesn't work well on round tubular rail. Fortunately you don't have that issue. Since we have a wider wheel we can run the back to back spacing narrower than NMRA standards because we'll still have tread left to stay on the rails while back to back spacing can more easily be made to allow the 3R switch guardrails to prevent the wheels from picking the frog. The downside is that they may still fall into the frog a bit and bump through the switch.

If you want to try them, buy 1 set of wheels only to verify they'll work for you. That way if they don't work with your switches it was only a small investment to find out.

quote:

While a few different turnouts may allow scale wheels to physically function over them, I personally don't know of any that do so in a way that meets my standards. I don't like seeing a wheel dip into the frog before being picked back up even though it may stay on track and not derail. I also don't like any switches that will do it but with the caveat that you not try to back up over it.

Fred and I are of a similar opinion on this issue. As I see it, one of the great strengths of 3 rail scale is operational reliability and the potential for realistic operation. Anytime you intentionally mismatch wheels and track you are undermining the reliability of your railroad.

We have yet to have a derailment at a switch during an NWTL operating session. And we have even run some Atlas and MTH 2 rail freight cars in operating sessions. But those two rail cars were deliberately placed near the tail end of a train and were not switched by either road or yard crews. They just had to travel forward and wouldn't have see significant lateral forces even if they had to make an unplanned reverse move.

With that said, operations of 2 rail cars on the three rail track of the Northwest Trunk Lines have met with a with fair degree of success. But they are noticeably more prone to derail than 3 rail cars, especiall on reverse moves. The NWTL has Scaltrax O-72, #4 and #6 switches along with ten handlaid switches that I built to Ross #6 curved and #8 curved switch patters using Scaltrax rail and Ross frogs. I have a high regard for the shape of both Scaltrax and Ross frogs. Both offer excellent results with the three rail trains for which they were designed.

If you look at Rich Battista's diesels you will notice that most of them have 3 axle trucks. Three axle two rail trucks on locomotives or heavyweight passenger cars do much better on 3 rail switches than 2 axle trucks due to the fact that two axles remain supported while one passes over the frog. That reduces or eliminates the dipping. But you still have 2 potential problems if you are running 2 rail wheel sets. First, you lose traction tires on diesel locomotives. With 3% grades your locomotive tonnage ratings may get unrealistically small. If your freight car fleet contains many Atlas Master Line cars it will exacerbate the problem since they tend to be on the heavy side. What is your standard train/siding length? Second, 2 rail wheel sets are insulated so you lose the advantage of 3 rails easy track detection if your railroad will be signaled.

Give your Ferdinand Magellan a try. You might find that those 3 axle trucks do pretty well.

I may have mislead you...in fact I know I did. I was looking at wheels that I have under the impression that they were .172 and .145 wheels when in fact they were very old .205 and .175 wheels. That changes things quite a bit considering my old .205 wheels are scale in appearance but with a tread that is .140 across. Their flanges are also a little bit taller. These wheels actually do work on tubular track. Most old wheels are not like these. I only have 2 sets of them.

I compared some of my old .175 wheels to NWSL .172 wheels and even though they are extremely close in appearance and size, the NWSL flanges are a bit thicker which means they have a little less tread. The difference isn't going to help much though.

I ran a properly gauged .172 wheel set across some MTH #4 switches I have and it is hit or miss. I do have 1 set of .145 wheels though and found that due to MTH grinding away a little bit of the inside rails for points fitment and a combination of the gauge going a bit wide, the .145 wheels can physically fall in between the rails. Again it's not saying they will but they certainly can.

So... .172 wheels "might" be able to be made to work but I'm not as confident as I was since I have now actually checked and measured them. They still won't work like I'd like them too though.

Bunch of videos at link of scale wheeled and 3 rail wheeled trains going through the switches, forwards , backwards and at speed.
Click on the thumbnail...



I run a combination of 2 and 3 rail on my Atlas tracked layout. o-54 and o-72 switches in the yard. O-72 and larger on the mains. All guardrails replaced with same height track set flange to flange spacing. Guardrails cut as short as possible should allow multi axles like steam engines and 3 axle cars and diesels to pass without binding.

Started out with NWSL wheel sets but these proved to be to unreliable. They had to be re gauged perfectly. Some cars never de railed and still have the narrow wheels. Was like running HO. All others were changed to Atlas 2 rail wheels that run perfectly all the time.

Have 4 Atlas GP9s converted to scale wheels and a Lionel E-7AA with P&D scale wheels get alot of run time. Even a Westside brass 2-8-2 converted to 3 rail tracks well when it runs.

http://rides.webshots.com/vide...88BBhsjO?vhost=rides

Are the guardrails on standard Atlas O switches not the same height as the running rails? They aren't on Ross switches either but they will build them that way if requested.

It looks like you've made it all work pretty well with Atlas switches and this may very well be what Bill needs to do.

All my Atlas switch were old and had the low guardrails. Too low to catch the scale flange. The whole process was trial and error testing engines and cars to make sure they all worked. It was fix the car or fix the switch.


The Lionel PS-4 flat cars would short out on a couple of the standard Atlas switches. Out of gauge wheels was the cause. They didn't like my converted switches either. They all get Atlas trucks and scale wheels. Have a variety of manufacturers coal hoppers. They were never a problem. They got Kadee couplers but kept the standard wheels mostly because of cost of converting. Same for the passenger cars.

Joe

Just curious and for reference, what is the width of the scale wheel sets offered by MTH, frieght and passenger ?

The problem you'll have with scale wheels is with two types of turnouts -- those with long frogs (#8) and those with through-curve frogs (O-72.) The #8 frog is very long so the gap is wide enough for the whole wheel to drop into and derail. Curved frog turnouts (O-72, etc.) have an arc and will derail scale-wheeled cars during backing moves as the wheels want to push straight. We've had very good success with Ross 11-degree turnouts (#5) and Atlas #5's.

My initial tests with MTH ScaleTrax #4's has indicated they'll work with scale-wheeled engines and rolling stock. I haven't tested the #6's yet, but MTH puts a bevel on the center of the frog which makes it more difficult for a wheel to pick the frog and derail.

I run several scale-wheeled cars and locomotives through the mainline turnouts on the club layout and they work fine. I keep them out of the harbor area as the curves are industrial sharp (O-54) and there are O-54 turnouts.

In the video below, a pair of scale-wheeled MTH U25's push a pair of scale-wheeled Atlas Trainman stock cars into a siding. You'll note the slight wobble of the car closest to the locomotives. That's typical of what I get with #5 turnouts.



Because other members also run scale-wheeled rolling stock, we put a "frog point" into a #8 curved turnout which fills the frog gap and moves with the points to provide a solid rail. It turns the frog issue into a non-issue. Here are two videos showing how it works.



Here it is in action:

A moving point or closed point frog is the only way to truly eliminate any problems. That one looks pretty nice.

Thanks Matt for the valuable info. Along with the info from the others I'm starting to "get it" as to what the issues are.

That moving point frog is simply amazing. How difficult was it to fabricate and install and whose switch machine do you use?

Fred or Matt is a "closed point" frog just another term for a "moving point" frog or is it another type? I've clearly never heard either of these terms before.

Thanks,
Austin Bill

The Atlas #5 double slip is NOT compatible with 2 rail wheel sets.

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But I also have a 2 rail Overland Ferdinand Magellan Presidential Ca

Did you check with Overland to see if they might have a pair of 3 rail trucks?

A movable point or swing point frog and a closed point frog are technically different. The movable point is like that one above where the frog point itself moves. A standard closed frog has a stationary frog point but the wing rails close up to it to eliminate the gap. Either way the result is the same. No gap. Closed point frogs are becoming more and more popular on prototype railroads. Another variation is the spring frog where the wing rails move but stay closed normally. They are opened only by the force of the wheel flanges moving through them. Some are buffered so that they close again slowly over a few minutes so they don't actually just spring back into place. There are lots of different switch designs out there. Everyone just concentrates on only 1.

Where in Austin are you? I'm in Houston but have family in Round Rock so I get out there several times a year. I'd love to see what you've got.

Hi Fred,

Suggest you email me at 844bill@gmail.com and I'll give you my address and mobile phone number.

Austin Bill

Hello,

Am I correct when I say that if one somehow retrofits a switch so that it is of a "closed" frog design that one can now run both 2 and 3 rail equipment on these switches? And that guard rails are not needed except for appearances sake?

And that the smallest rail that can be used that will accomodate 3 rail equipment is code 172 rail?

Thanks in advance,
Steve

Gentlemen:
I am a 3RS man. I have been running 2 rail equipment on Atlas 3 rail track for 8 to 10 years. Turnouts are #7.5 crossovers and #5 in the yard. If you chamfer the point of the frog and build up the guard rails on the #5 turnouts back up moves become derailment free. You only need to build up the guard rail on the curved part of the turnout.
My freight cars have Athearn, Atlas, Intermountain, MTH,and Weaver wheelsets and I don't have a problem with any of them. I also have a 80' combine with Walthers 6 wheel trucks that is derailment free.

George

Steam guy: assuming of course that it's built properly the answer would be yes to that. Guardrails aren't needed anymore. The trick to it is to somehow make the points rails insulated in the middle so that the pickup rollers don't short out crossing over them. There are a number of ways to do this but it's a bit tricky. Everything has a compromise.

Soo Nut:

Do you have photos of the turnout modifications? I'd be interested in that option for some of our turnouts.

quote:

Soo Nut:

Do you have photos of the turnout modifications? I'd be interested in that option for some of our turnouts.

I second that request!

George (Soo Nut)- It looks like you have a fan club. I'd like to see your mods if possible.

Hello Matt and fellow modelers:
Following are a couple of photos of my modifications to Atlas 3 rail turnouts inorder for two rail equipment to operate. It may be a little hard to see, but I super glue a piece of .010X.0625 plastic to the top of the guard rails on the curved part of the turnout.

Thanks. Up until this point, I hadn't seen a reliable way to deal with a frog that large. Looks like the guard rail extension keeps the smaller flanges from riding over the guard rail, while the tapered tip of the frog keeps the wheel going the right way during the "wheel drop." Good work.

Soo Nut - Thank you, great Tip! Thanks for taking the time.

I'm slooowly starting my new layout and am trying to iron out all the Atlas issues I and before I get too permanent. I don't want to go back again after ballasting.

I know it isn't true on all track but there are many prototype switches here that have a taller guardrail than running rail.

Great thread! Thanks for all the info.

The question that I have about modifying the Atlas switches in this way is whether or not scale wheels can still fall into the frog gap? Just because it doesn't derail doesn't mean it still doesn't fall into the frog. Chamfering the frog point would only leave a larger distance for the wheels to go before being fully supported again.