Code 88 wheels?


Mike Brock <brockm@...>
 

Code 88 wheels certainly seem to be of interest to those on the STMFC these days. Given that, I decided to analyze the dimensions of one...an Intermountain wheel.

Here's the results:

Wheel Flange width Tread width Wheel width Wheel dia.
Intmtn 88 0.031 0.0468 0.088 0.428

NMRA 88 0.025 0.063 0.088 ?

NMRA 110 0.030 0.080 0.110 ?

Code 110 0.031 0.070 0.110 0.428

The NMRA 88 and NMRA 110 are taken from the NMRA RP-25 table. Intermtn 88 is the Intermountain code 88 wheel, the Code 110 is a P2K Code 110 wheel.

My measurements of the tread are accurate no better than to 1/64...0.0078. From what I see, the Intermountain Code 88 wheel that I examined appears to be a Code 110 wheel with a wheel width simply reduced to that of a Code 88 NMRA specification. Hence, the wheel has the same code 110 flamge. Interestingly, the resulting tread size would be a bit less than that specified for a Code 88 wheel...which is born out by the measurement. There appears to be no doubt that the diameter of the wheel at the flange is the same for the Code 110 and Code 88 wheel and the measurements on wheel widths are accurate.

Note that I only examined the Intermountain Code 88 wheel. I'll take a look at a NWSL wheel later. Perhaps Marty McGuirk
might want to comment on the Intermountain wheel. Note that I am only referencing a particular Intermountain wheel. Intermountain...and other manufacturers...may have other Code 88 wheels that are, indeed, truly Code 88 as specified by the NMRA.

It would be interesting to see what others might find by performing similar measurements on the same and other wheels.

Mike Brock


Tim O'Connor
 

Mike, .031 + .047 = .078 not .088. You want to remeasure?

Also .031 + .070 = .101, not .110. Is that the standard?

Tim

Wheel Flange width Tread width Wheel width Wheel dia.
Intmtn 88 0.031 0.0468 0.088 0.428
NMRA 88 0.025 0.063 0.088 ?
NMRA 110 0.030 0.080 0.110 ?
Code 110 0.031 0.070 0.110 0.428


Martin McGuirk <mjmcguirk@...>
 

Mike,

The Code 88 wheel is a compromise -- it offers the improved appearance of the narrower tire width with some comprises to work reliably on standard NMRA track and turnouts. In short, you're right, the wheels are standard IRC wheelsets with narrower wheel width. They are not (and aren't intended to be) Proto 87 wheels. I know NWSL sells P:87 wheels -- I don't know if they make "code 88" wheelsets.

It's similar to the "smaller" Kadee couplers (the 58 and 78) they are not truly scale size, but offer a workable compromise with improved appearance.

Iain Rice has often warned me, based on his experience with P:4 in England, that the "almost P:87" isn't really workable long term as it will cause too many variations and deviations from the standard. In theory, if everything was made to true P:87 specs it would have to work together since the real thing does -- the Brits learned that the hard way -- and it's one of the reasons they have OO, EM, and Proto: 4mm today, meaning most of their rolling stock and virtually none of their locomotive kits include wheels!!!

Of course, the main advantage true P:87 offers is improved appearance of track -- not rolling stock. If the goal is narrower wheels and smaller couplers the semi-scale wheels and 58, 78, and Accurail Proto size couplers offer workable, practical alternatives.

Marty McGuirk


RichBeau <RichBeau@...>
 

I pulled out a couple of the Reboxx wheelsets I just purchase and
measured these.

Wheel Flange width Tread width Wheel width Wheel dia.
Reboxx 0.028 0.06 0.087 0.428


Now the tread width is hard to measure since there's a radius where the
flange meets the tread. Hence the two place figure. I'd need a
good "mike" rather then my digital vernier.

Also Mike shouldn't the flange width plus the tread width be at least
close to equaling the wheel width? If so why is the Intermountain code
88 wheel a bit off? .0778 versus .088

--Rich


Mike Brock <brockm@...>
 

Marty McGuirk writes:


The Code 88 wheel is a compromise -- it offers the improved
appearance of the narrower tire width with some comprises to work
reliably on standard NMRA track and turnouts. In short, you're right,
the wheels are standard IRC wheelsets with narrower wheel width. They
are not (and aren't intended to be) Proto 87 wheels. I know NWSL
sells P:87 wheels -- I don't know if they make "code 88" wheelsets.
But, they also are not truly Code 88 wheels. I referred to these wheels as Code 88T because I thought they were Code 88 treads on Code 110 flanges. It turns out that the treads would be slightly smaller than those for Code 88 because, while the wheel total width is Code 88, the flange is Code 110 meaning that the tread must be smaller than that of Code 88. I'll still refer to them as Code 88T. Regretfully, the analysis I did on the damned thing's ability to negotiate turnout frogs was based on a true Code 88 tread size. No...I'm not going through all that again...Not anytime soon anyhow. Applause is appreciated.

Of course, the main advantage true P:87 offers is improved appearance
of track -- not rolling stock.
A very astute observation. Not many realize just how much larger the flangeways and even the length of our frogs are compared to the prototype. I would speculate, however, that even with P87 wheels and associated track, our much smaller turnout frogs would require longer guard rails and wing rails than the prototype [ because of the sharper curves ]. For example, I'll admit to much longer guard rails because I want my long wheel base locos to be where they should be long before encountering the frog in order to eliminate quick, last second movement away from the frog. I might also note that even with correctly P87 sized frogs, we would still need to address the frt yard sized turnouts [ #8 ] that most use on the mainline.

If the goal is narrower wheels and
smaller couplers the semi-scale wheels and 58, 78, and Accurail Proto
size couplers offer workable, practical alternatives.
Yes.

Mike Brock


Mike Brock <brockm@...>
 

Rich Beau writes:


I pulled out a couple of the Reboxx wheelsets I just purchase and
measured these.

Wheel Flange width Tread width Wheel width Wheel dia.
Reboxx 0.028 0.06 0.087 0.428


Now the tread width is hard to measure since there's a radius where the
flange meets the tread. Hence the two place figure. I'd need a
good "mike" rather then my digital vernier.

Also Mike shouldn't the flange width plus the tread width be at least
close to equaling the wheel width? If so why is the Intermountain code
88 wheel a bit off? .0778 versus .088
The wheel width should be exactly the flange width plus the tread width. Note that I said I couldn't measure either flange or tread width closer than 1/64...Oooops...I meant 1/128 which is the .00781 is what I wrote. Forgot that I halved the 1/64. Anyhow, add .0078 to .0468 + .030= .0846 certainly well within the 0.088 ball park.

Given the diameter of the wheel being the same as my Code 110 it sounds like the Reboxx wheel is also a Code 88T.

Mike Brock






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Schuyler Larrabee
 


Marty McGuirk writes:

The Code 88 wheel is a compromise --
Brock counters:
But, they also are not truly Code 88 wheels.
Sure they are, Mike. They're Code 88 because they measure .088" front face to back face. That's
what "Code" means, nothing more.

What you mean is that they are not an RP25 Code 88 wheel. You're right about that. IM wheels
aren't; Reboxx wheels aren't. Not sure about the others. What the IM and Reboxx wheels are, is
exactly what you said: Code 88 wheels with Code 110-thickness flanges. I've been noting that on
this list for at least two years.

SGL


Jon Miller <atsf@...>
 

I know NWSL
sells P:87 wheels -- I don't know if they make "code 88" wheelsets.<
I bought NWSL 40" (or 42", I forget) wheels to retro-fit my PFM 4-8-4s
and think they were advertised as code 88. Never measured them or looked
that close except they are narrow tread and look much better on those
engines.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


Mike Brock <brockm@...>
 

Tim O'Connor says:


Mike, .031 + .047 = .078 not .088. You want to remeasure?
Nah. As I mentioned, I cannot measure the point where the flange and tread meet any more accurately than about 1/128. [ +/- 0.0078 ] Same for the Code 110 wheel. .101 + .0078 =0.1088. Well within the ball park.

Mike Brock


Dennis Storzek <dstorzek@...>
 

--- In STMFC@..., "Mike Brock" <brockm@...> wrote:

Tim O'Connor says:


Mike, .031 + .047 = .078 not .088. You want to remeasure?
Nah. As I mentioned, I cannot measure the point where the flange and
tread
meet any more accurately than about 1/128. [ +/- 0.0078 ] Same for
the Code
110 wheel. .101 + .0078 =0.1088. Well within the ball park.

Mike Brock
So... Mike wants to quibble over .002" on the depth of the flange and
.005" on its width, but can't measure closer than +/- .0078????

Dennis


Martin McGuirk <mjmcguirk@...>
 

I find it even more fascinating that the Reboxx and Intermountain measurements aren't identical - which leads me to believe the issue is with the measurer, not the measuree (the wheels).

Consider also that the surface of the wheel is not truly flat, and the flange increase slightly in width from the outer edge of the flange towards the tire surface. So, if you don't measure theses various dimensions at the exact same point you're from wheel to wheel you're going to get discrepancies.

But, rather than worrying too much about this you need to (1) figure out a way to get a truly accurate, consistent, measurements OR (2) simply accept the fact that "the wheels are narrower and look better." Quibbling over .0XX whatever of an inch, when no one has gottne a consistent measurement, seems academic at best.

Marty McGuirk


Mike Brock <brockm@...>
 

Dennis Storzek notes:


So... Mike wants to quibble over .002" on the depth of the flange and
.005" on its width, but can't measure closer than +/- .0078????
Actually I can measure quite closely...having extremely good close up eyesight. What I cannot do is tell exactly where "W" extends to on the flange...thus, making my measurements of "W" and "T" unreliable...with an error possibility of "about" .00778. Could the error be greater...to say...0.009? Yep.

As to the depth of the flange, I can put my micrometer on the wheel's diameter including the flange fairly reliably. When the readings were the same, I was lead to suspect that the manufacturing process was merely to reduce the tread size on a Code 110 wheel...which, apparently, is what happened...at least in two cases.

Mike Brock


Jim Betz
 

I'll chime in with a different approach to this topic ...

Background ... one of the things that differentiates two
wheelsets is the shape of the curve where the flange meets
the tread. Pick up two wheelsets and look at them and you
will notice differences in this area right away. This is
especially noticeable if you compare some cheapo wheelset
with an Intermountain or Reboxx wheelset.
Similarly ... the angle of the tread from true horizontal
is also different from one kind of wheelset to another.

Perhaps a more useful method of 'measuring' a wheel would be to
develop a method for consistently photographing it edge-on and
showing the profile for comparison?
I'm thinking that if I had an accurate profile of the shape and
size of two wheels either alongside each other or one on top of
the other that I could see the differences - without knowing
the measurements. If I had the images I could even 'cut' one
and carry it up over the other one and see the two shapes very
precisely.

Such a method would have to be able to repeatedly reproduce the
same profile for the same wheel - and the relative profile shape
and size of wheels from different manufacturers/models. But I'm
guessing that the combination of a jigged camera set up that
precisely controlled the distance of the camera from the axle
and some controls of the way the image is taken (camera zoom
settings, etc.) - combined with some photoshop filters that repeated
the image changes - would produce jpg profiles that could be relied
upon and used for comparison. Luckily, it seems that the overall
width of two wheels claiming to be Code 88 is close enough to
each other that one ought to be able to determine easily whether
or not two photographically developed profiles are the same or
different.
I know that such a method would be subject to the possible
variations introduced during manufacturing ... but that is
both a good thing and a bad thing. Good because it is what
actually gets produced that counts rather than what the designer
of the wheel thought they would be. Bad because it is possible
that you might use a wheel that is significantly different from
the norm for that manufacturer and model. If you ran several
'identical' wheels from the same manufacturer thru the process
you ought to be able to know if they are coming out the same
or not.

Finally - I'd also like some kind of operational data tossed into
the mix as well - stuff like which wheels have problems with which
existing turnouts, etc. From actual experience.
- Jim in San Jose


Mike Brock <brockm@...>
 

Schuyler Larrabee writes:

Marty McGuirk writes:

The Code 88 wheel is a compromise --
Brock counters:
But, they also are not truly Code 88 wheels.
Sure they are, Mike. They're Code 88 because they measure .088" front face to back face. That's
what "Code" means, nothing more.
As I noted...I hope...long ago in this thread, I refer to the NMRA definition of Code 88, Code 110 or any other code as defined in RP-25. While the NMRA Code 88 wheel DOES have a total thickness of 0.088", it has other dimensions as well, including tread size and flange sizes. All of these dimensions together describe the NMRA Code 88 wheel. A far as I know, no one else has published a different definition of a Code 88 wheel. I DID say that I would call a wheel having a code 88 tread with a Code 110 flange a "Code 88T" wheel to differentiate it from a true Code 88 wheel. Since it turns out that this wheel might not exist and is, in fact, a Code 110 wheel with a reduced tread so that the entire wheel width is 0.088", I'll use the term Code 88T to define THAT wheel...in case a true Code 88 shows up sometime.


What you mean is that they are not an RP25 Code 88 wheel. You're right about that. IM wheels
aren't; Reboxx wheels aren't. Not sure about the others. What the IM and Reboxx wheels are, is
exactly what you said: Code 88 wheels with Code 110-thickness flanges. I've been noting that on
this list for at least two years.
Well...I glad someone is alert.<G>.

Mike Brock


mjmcguirk@...
 

Mike,

Call me curious, but is there another issue (operational) that's causing you to spend time on this??) -- or is it simple idle curiousity???

And, before anyone spends an inordinate amount of time comparing apples to apples let me clarify something I hinted at in a previous post -- you shouldn't be able to find any difference between InterMountain and Reboxx wheels (outside of machining tolerances) since the wheelsets are identical -- made by the same machine, tossed into the same parts bin in the factory, and only separated when it comes time to press them onto their axles.

Marty McGuirk


Dennis Storzek <dstorzek@...>
 

--- In STMFC@..., "Mike Brock" <brockm@...> wrote:


As to the depth of the flange, I can put my micrometer on the wheel's
diameter including the flange fairly reliably. When the readings
were the
same, I was lead to suspect that the manufacturing process was
merely to
reduce the tread size on a Code 110 wheel...which, apparently, is what
happened...at least in two cases.

Mike Brock
I'm sure you're correct, but as I explained the oher day, not only
doesn't it make any difference, it actually works to our advantage.
However, since these are not Code 88 wheels as specified in NMRA
RP-25, how about we just call them semi-scale wheels from now on?

Dennis Storzek


Anthony Thompson <thompson@...>
 

Dennis Storzek wrote:
I'm sure you're correct, but as I explained the oher day, not only
doesn't it make any difference, it actually works to our advantage.
However, since these are not Code 88 wheels as specified in NMRA
RP-25, how about we just call them semi-scale wheels from now on?
Probably you mean "semi-code" wheels? Anything even close to RP-25 is a HUGE flange compared to scale.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history


Tim O'Connor
 

Dennis & Mike

I've just called them .088 wheels all along; works for me. Heck,
.110 wheels are "semi-scale", if I understand the meaning of the
"semi" prefix.

I'm sure you're correct, but as I explained the oher day, not only
doesn't it make any difference, it actually works to our advantage.
However, since these are not Code 88 wheels as specified in NMRA
RP-25, how about we just call them semi-scale wheels from now on?

Dennis Storzek


Dennis Storzek <dstorzek@...>
 

--- In STMFC@..., "Schuyler Larrabee"
<schuyler.larrabee@...> wrote:

Sure they are, Mike. They're Code 88 because they measure .088"
front face to back face. That's
what "Code" means, nothing more.
That's not correct. The "Code 88 wheel" is only described in NMRA
RP-25; without the definition, the "code" doesn't mean anything. The
definition most certainly specifies many more dimensions than just the
width; this was the whole idea behind RP-25, to specify a well
engineered wheel profile that could be adopted in any scale, so
manufacturers would stop making those God-awful wheels with sharp
angular "pizza-cutter" flanges and no fillet. At least RP-25
recognizes the importance of the fillet between the flange and tread.

The problem is that compliance with the older standards requires the
use of an RP-25 wheel of a "Code" size vastly larger than scale;
indeed. the Code 110 wheel commonly used in HO scale is really a
PROTO:48 wheel; if enlarged 48 times, it would be within the AAR
limits for wheel wear in all it's dimensions. Keep in mind that RP-25
doesn't say anything about the diameter of the wheel; the HO freight
car wheel would be a 18" speeder wheel in P:48, but the profile would
be correct.

Considering that the narrow tread wheels from several manufacturers do
not conform to the specifications for a Code 88 wheel as defined in
NMRA RP-25, I propose we just call them "semi-scale" wheels.

Dennis Storzek


Jon Miller <atsf@...>
 

I propose we just call them "semi-scale" wheels.<
NWSL calls theirs semi-finescale /88 tread. Not sure what they use for
a flange as it hard to look up their products.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS