NMRA Bone-headed move to RP25


T

TomR

Member
Well, I just got off the phone with a manufacturer and found out why my new engines and cars derail all the time.

According to the manufacturer, the problem is the RP25 wheel standard by NMRA. They said they get returns all the time now because the RP25 standard has the wheel flanges too shallow.

The manufacturer told me they warned NMRA about this, and NMRA went ahead and changed to the RP25 anyway.

My choice is to rip out all my code 100 track and go to a code 83, and to pay particular attention to the types of turnouts I buy, or just not buy newer rolling stock and engines. The fellow on the phone said the new RP25 stuff is a headache no matter how careful the layout when it is code 100 rail.

What a bone-headed move by NMRA. I'll have a garage sale and go find something else to do before I spend hours on end machining my own wheels. What the heck were they thinking?

So now I know. With code 100 track and Atlas turnouts, I'm just shafted for ever buying something new if the wheels are made to NMRA RP25 standards. At least that is what the manufacturer says, and that is what my own measurements and test on my track also show.

In a small market like this, a bone-headed move like RP25 is a big problem. I wonder how many people were working like crazy to fix problems caused by new wheels?

Where can I buy old wheels with taller flanges in a 1 inch axle width?? Anyone know??

Tom
 
I though RP25 has been the standard for a long time. The current version of the standard was written almost 14 years ago (July, 1997). I also doubt that the NMRA can tell manufacturers what to do.

I hope you get things running properly without having to replace all your rail. That would be terrible.
 
TomR said:
Well, I just got off the phone with a manufacturer and found out why my new engines and cars derail all the time.

According to the manufacturer, the problem is the RP25 wheel standard by NMRA. They said they get returns all the time now because the RP25 standard has the wheel flanges too shallow.

The manufacturer told me they warned NMRA about this, and NMRA went ahead and changed to the RP25 anyway.

My choice is to rip out all my code 100 track and go to a code 83, and to pay particular attention to the types of turnouts I buy, or just not buy newer rolling stock and engines. The fellow on the phone said the new RP25 stuff is a headache no matter how careful the layout when it is code 100 rail.

What a bone-headed move by NMRA. I'll have a garage sale and go find something else to do before I spend hours on end machining my own wheels. What the heck were they thinking?

So now I know. With code 100 track and Atlas turnouts, I'm just shafted for ever buying something new if the wheels are made to NMRA RP25 standards. At least that is what the manufacturer says, and that is what my own measurements and test on my track also show.

In a small market like this, a bone-headed move like RP25 is a big problem. I wonder how many people were working like crazy to fix problems caused by new wheels?

Where can I buy old wheels with taller flanges in a 1 inch axle width?? Anyone know??

Tom
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Tom;

Very interesting that a manufacturer would complain about RP-25 flanges now, esp. since that RP has been in place since the early 1960's, if not before then. I remember seeing ads from that time for Lindberg Trucks, stating that they now come with the RP-25 wheels.

He's gotta be blowing air up your skirt. I use code 83 and code 70 rail now, and in the past even had some code 40 rail on a couple of earlier layouts. Even on that very small rail, I have no problem with derailments, AT ALL! 99.9% of my cars and all of my locos have RP-25 flanges.

In fact, except for older used equipment, or some European made equipment made to the older NEM standards, it's almost impossible to buy anything with RP-25 wheels or its equivalent.

It was proven many years ago, that its not the flange depth that determines trackability. Its the fillet between the flange and the wheel, and the quality of the trackwork.

To make a long story even longer, its your trackwork, and not your flanges.
 
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Heck if you're going that far back based on what one person said, why not get some track w/ brass rails & fiber ties. LOL Best advice for you is get other opinions & do more reading on the subject. The whole purpose of those "flange cutter" wheels was to keep rolling stock on very bad laid track
 
cajon said:
Heck if you're going that far back based on what one person said, why not get some track w/ brass rails & fiber ties. LOL Best advice for you is get other opinions & do more reading on the subject. The whole purpose of those "flange cutter" wheels was to keep rolling stock on very bad laid track
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Well, if the manufacturer is wrong I'd sure like to know about it.

I can't trace the history because the old pdf data is gone from the NMRA site, and stuff more recently written or revised is up. I have no idea what was there 5 or 10 years ago, but it obviously has been revised several times.

If he is wrong then a second manufacturer is also wrong, because I just measured the wheels on a new Bachman locomotive and they are shallow flanges also. They are about .015 inches flange height with a radius from the running surface onto the flange.

All of the other older wheels I have are about .026 inches flange height with a visually sharper turn from the running surface onto the flange. They stay on the track fine. I can run through turnouts full speed, and back through curves and turnouts with no problem with the .025 inch flange height wheels. These new soft radius low height flanges derail when backing through a 24 inch radius curve, and NOT at the joints. They derail on smooth level areas even with slow careful backing of short trains.

They also bounce more going across frogs.

Tom
 
Have you checked your track w/ an NMRA track gauge or did that same manufacturer say those were no good also? Like others have said bad track work can cause all kinds of problems.
 
Wheels

All of my rolling stock and engines have metal RP25 wheels and I have no problem what-so-ever on code 100 track. I try to run my equipment at what I consider scale speed and even in some tight short turnouts everything works fine.

The fillet between the wheel and the flange is to allow the wheel to adjust for track irregularities. All track has irregularities, no mater how well laid. Older deep sharp flanged wheels didn't allow for that adjustment by the wheels.

One thing that will cause any wheel to derail is irregular trackwork and I'm not just talking about rail joins. Track must be level and transitions to grades must be gentle. Even curves can be level, and even super-elevated, without equipment coming off the rails. But, never, never allow the outer rail of a curve to be lower, even by a fraction, than the inner rail. You'll be calling for the wrecker.

Hold off on the garage sale. Try to find someone in your area to help determine the root cause of your problem. I'm sure it's not the wheels.

Just my thoughts.

Roy
 
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cajon said:
Have you checked your track w/ an NMRA track gauge or did that same manufacturer say those were no good also? Like others have said bad track work can cause all kinds of problems.
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Yes. I have an NMRA template and all is fine. I even built my own radius measuring truck to check for flaws in curve radius.

The difference between the newer wheels and older wheels is phenomenal. If I place a weighted truck from one of my new cars on a straight section of track and push sideways with a gauge that measures pressure, 1/4 oz or so will derail the newer wheels. A couple older spare trucks I have using old wheels with .025 inch flanges, with the same weight on them, require over 2 oz of side thrust to derail!!


I'm not sure how linear or repeatable the test is, but that's a huge difference in side force required to derail a stationary truck with the same weight. I see now why the newer wheels derail when backing through curves.

By the way, the curve I'm testing backing on is a nominal 24 inch radius made from flex track. The effective radius measures between 23 and 25 inches all around the curve, except the end transitions blend with increasing radius until straight.

So they are not lumpy, and do not change angles. The cars don't derail at joints (I use staggered joints and they are soldered). They derail in the smooth 24 inch areas as soon as there is any back-pressure from pushing cars through the curve. The new wheels bounce more in frogs, and derail there too at times.

I can run backwards through the same curve and turnouts and never have a problem with older wheels. All my stuff is code 100.

Tom
 
Couplers

Tom, one of the easiest way to derail is to have truck mounted couplers. Not sure if this is your situation, but I thought it might be worth mentioning. Body mounted couplers allow the trucks to move freely. Truck mounted couplers should only be used on very long equipment like 80' passenger cars.

Roy
 
Roy is correct here. Truck mounted couplers are extremely bad for backing.

As for the "dropping" in the frog, (bet they are Atlas turnouts. That's OK, I use them in my staging yards), the flangeways in all but a few commercial turnouts are a compromise. They not only have to accommodate RP-25 wheels, but they also have to work with the old obsolete pizza cutter wheels as well. Its these compromises that can cause the derailments. There are ways to correct these faults, easily too.

You live around Macon. I wish there was a way for you to come to B'ham to see my set up. I believe that a few hours with me would benefit you immensely.

Just ask Rex! (Rexhea)
 
It's not the RP-25 that people usually have problem with but the narrow width wheels. They look more prototypial but the tread is much thinner. Those tend to fall in frogs.
 
hamltnblue said:
It's not the RP-25 that people usually have problem with but the narrow width wheels. They look more prototypial but the tread is much thinner. Those tend to fall in frogs.
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There was a new standard created a year ago to better replicate prototype dimensions, it was thought it would replace RP25 but never did. I believe what you have issues with are NOT RP25 but this new design, called Proto87. http://www.proto87.org/d/
 
I believe Tom was mistaken as well, confusing semi-scale .088" wheelsets for RP-25 sets which have been the standard for years. I know Athearn used the finer wheelsets on some early genesis cars that cause me trouble, and they have since reverted back to the RP-25 wheelsets. I'm not sure which other manufactures have included the finer wheelsets on their equipment.
 
I thought about Proto87 when this discussion started, but I'm not aware of anyone using them these days. They would definitely be a problem on older code 100 turnouts.
 
The NMRA does not dictate to manufacturers what they must do. Conformance is voluntary and there is plenty of stuff out there that does not comply with standards. As has already been said, RP-25 has been around for a long time. Backing long trains is an acid test. Truck mounted couplers will make this near impossible. Also, consider that if your wheels were the problem, it wouldn't matter which direction the train was moving. If you'd share what cars we're talking about, maybe we could help a little more. Also check weight. Under weight cars will derail more easily that properly weighted ones. That guy on the phone was shining you on!
 
Espeefan said:
The NMRA does not dictate to manufacturers what they must do. Conformance is voluntary and there is plenty of stuff out there that does not comply with standards. As has already been said, RP-25 has been around for a long time. Backing long trains is an acid test. Truck mounted couplers will make this near impossible. Also, consider that if your wheels were the problem, it wouldn't matter which direction the train was moving. If you'd share what cars we're talking about, maybe we could help a little more. Also check weight. Under weight cars will derail more easily that properly weighted ones. That guy on the phone was shining you on!
Click to expand...

I appreciate all this constructive feedback. I must admit the person on the phone got me all wound up:

1.) My tracks are fine. They measure good and the radius is large, I can back a four foot long train with truck mounted couplers through with no problems.

2.) I was backing a fairly short train. Just three brand new cars and a free-rolling caboose. The cars are pretty heavy, and the couplings are on the frame not the truck.

3.) RP25 might have been around a long time, but it looks to me like the dimensions are subject to picking one out from a bunch of codes. :)

Soooo....... here is my question.

If I change the wheels to wheels with .025 inch flange height above the rail contact surface of the wheel, problems vanish.

These wheels have a flange height above the running surface of .015 inches.

NMRA has this dated July 2009:

http://www.nmra.org/standards/sandrp/pdf/RP-25 2009.07.pdf


and they have this dated 1997:

http://www.nmra.org/standards/sandrp/rp25.html

Both seem to agree. However, all my wheels that work well have a .025 flange depth, which would imply code 110 in both.

The new wheels that derail look like they are code 54 in both.

Did NMRA change and encourage the use of code 54 on HO layouts??? Or do they use 110??? Or what??

Things I measure that appear to be code 110 work great.

Tom
 
are you sure the trucks are not warped? are the wheelsets all metal? are the cars jumping across or sliding across the rail when they derail? you may not have a wheel or track problem. bigger wheel flanges might help, but probably wont fix the underlying problem.
 
As noted earlier your problem is probably with the truck mounted couplers. If you hook a truck mounted coupler to a body mounted one, derailments can easily happen. The body mounted coupler is going to pull the truck mounted off the the side and possible right off the track in turns.
 
wright2626 said:
are you sure the trucks are not warped? are the wheelsets all metal? are the cars jumping across or sliding across the rail when they derail? you may not have a wheel or track problem. bigger wheel flanges might help, but probably wont fix the underlying problem.
Click to expand...

These .015 inch tall flange wheels push sideways off the track much easier than wheels with .025 inch tall flanges. I don't mean a little bit, I mean a whole lot easier.

They are plastic wheels. The trucks all sit flat. The cars feel like they are about the right weight, they are pretty heavy for the size.

The manufacturer says "we have a lot of complaints since the standards changed and we can't get taller flanges".

and once again....the cars don't have truck mounted couplers.

The tracks are probably about as as perfect as anyone can lay. The leading wheelset on a leading truck just suddenly pops over the rail. It does this at random spots (or when hitting the frog in turnouts).

Tom
 
Here is my real question again that has me stumped. This is what I think will help me out, if I can get answers to this.......

If I rob other cars of wheelsets (metal or plastic) that are 1.00 inches wide axel point-to-axel point and swap in wheels with .025 inch flange height above the rail contact surface of the wheel, all problems vanish. These new cars are impossible to make derail. I can run backwards through turnouts and curves full speed.

With the brand new plastic OEM wheels that have a flange height above the running surface of .015 inches, I have the headaches.

NMRA has this dated July 2009:

http://www.nmra.org/standards/sandrp...%202009.07.pdf

and they have this dated 1997:

http://www.nmra.org/standards/sandrp/rp25.html

Both seem to agree. However, using that NMRA chart all my wheels that work well have a .025 flange depth, which would imply code 110 in both.

The new wheels that derail look like they are code 54 in both, based on my measurement of flange height with calipers.

Did NMRA change and encourage the use of code 54 on HO layouts??? Or do they use 110??? Or what??

Things I measure that appear to be code 110 work great.

Tom
 
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