Dear Mr. Hayden,     Thanks for your email of the 28^th of May, in which you correctly pointed out that there are differences in dimensions between our semi-scale wheelsets with .088 treads and the Code 88 wheelsets spec. It's a subject that could use some enlightenment among us model RR types. I am glad to give you a little background on this matter.

 

Many years ago in the mid-eighties, on one of my business trips to the Melbourne, FL area, I arranged to meet with A.B. Bradley, who was influential in the inner circles of the NMRA in those days. It turns out that Brad, as he was called, had made up the NMRA wheel standards which incorporated the RP-25 idea used first in the fine trucks manufactured by George Hook of Central Valley. One thing still sticking in my mind is how Brad rationalized the dimensions of the .110 version of HO wheels and the absolute scale version, first figuring out the .110 dimensions from the various manufacturers' versions, cutting to  'arbitrarily chosen'  values for the middle of those. [The most key dimension of the RP-25 version was the flange to wheel radius.] He then calculated a single set of values for the HO version of the scale full size wheels. To satisfy his own desires, or those of others involved (think committee or compromises), he then created dimensions for a compromise wheelset with an average of .110 & .067 as a tread width. Thus, the "Code 88" was born. There is nothing from heaven, nothing magic, nothing even seriously institutional about this .088" wheelset. Moreover, until you reminded me about NWSL making some of these, I had forgotten that any were actually produced. The problem, of course, is that all of the dimensions are different from the .110. The Code 88 doesn't go through anyone's switches successfully unless the switches are specially dimensioned and made to fit its tread width and flanges. Thus, it has never became a commercial product.

 

Our .088's began from a different azimuth. Back in the days when I was closer in association with Intermountain, I saw that IM had as part of its wheelset line a .088 wheelset with one fixed length axle, namely 1.012 +/-. I asked, " How does it work in use?" The answer was "Fine" What did "fine" mean?  I pressed on with questions until the answer seemed to be that no more complaints in proportion to the number of .088 and .110 wheelsets in use were received for .088. So, I developed a rational for why the .088's were working so well.

 

It turns out that the outer .022 of the wheelset doesn't actually touch anything in correctly spaced frogs; it just spins away in the air as it rolls. I wondered: if it doesn't touch anything, why have it? The .110 looks fat and ugly. Why not give it a trim and make it look more realistic? Why not save material in the manufacturing process? One anticipated problem was what if the wheel couldn't be consistently assembled on the axle perpendicularly? (It does have less distance along the axle to keep it straight). On trial, we found that carefully assembled wheelsets, even on insulating bushings, ran without measurable runout. At this point, we had a new resource. The next idea was key to the success of the Reboxx wheelset; that was to make wheelsets with all the necessary axle lengths to fill wheelset sockets in all the main trucks in use, thereby getting rid of a myriad of problems in operation caused by wheelsets of improper length.. HO trucks in use today vary substantially in socket length; the actual variation runs from below .0940" to above 1.070", a range of over .130", or just above an eighth of an inch, causing all kinds of tipping and yawing problems and even in rare cases, sticking axles where the axle is too long for the socket. A too long, stuck axle is a recipe for an early derailment, just as short axles are.

So you can see that we came to the .088 wheelset from a different direction, namely, if it isn't being used, don't have it. And geometrically, start with a .110 wheelset, cut off the non useful outer .022" part and come out with a .088 tread. We at Reboxx have never used the Code 88 label, because we start and end with a .110 flange. We made our own version of an .088, not the Code 88 version. Our wheelsets have been selling well after 15 years in the marketplace and are running on most of the best model RRers' layouts.

 

 If you check the NMRA switch dimensions, you will see that theoretically the .088 works. There's no wheel dropping in the middle of a frog. However, in the case where a switch's dimensions don't follow the standard dimensions, all bets are off. Once in a great while, we hear of the .088 wheelset operating as a gauge to find defectively made switches.

 

Now, you may think that what I'm about to say is a unnecessary detail. It turns out that all wheelsets drop in moving through all frogs, wheelsets with tapered treads, that is. In a view from above, the contact point on the wheel, as the wheel moves through the frog, is first on the radius between the flange and the tread. At the spot where the wheel leaves the center rail, at the exact point of the frog, the contact point switches to the outer edge of the tread. Now, switch to the horizontal view: the diameter of the wheel at the outer edge of the tread being less than up next to the flange, all tapered wheels drop the radial difference in dimension. And, then as the new rail moves in to become a straight extension of the rail from the point, which the wheel just left, the contact point on the wheel moves back in to the same area on the flange-tread radius from which it departed. Another way of describing this action is to say that the wheelset CLIMBS during the interval between first contact on the second rail and resuming its journey through the second half of the frog.

 

We were battered in the beginning fifteen years ago by naysayers who maintained that our .088's couldn't possibly work. Among the objections was: it'll drop in the frog. This turns out to be correct. It will drop exactly the radial difference between the inner and outer parts of the tread, in our case about .002, in the case of the .110, about .003. If it drops dramatically more, the switch isn't made correctly. The next objection we heard a few times was: it will wear out my frog points. That's also exactly correct, and in an observable time only on public layouts that run on public display continuously for a full day shift six to seven days a week. All intermittently run layouts, private and club, have points that will outlast the members. Suggests we ought to give more priority to members' life spans, rather than frog points'.

 

Brad Bradley did excellent, excellent work. We just need to be careful not to apply the primatur of God to it.

 

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From: info@... [mailto:info@...]
Sent: Thursday, May 29, 2014 8:52 AM
To: J P Barger
Subject: FW: Code 88 wheels
Importance: High

 

 

 

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From: Hayden, Thomas [mailto:Thomas.Hayden@...]
Sent: Wednesday, May 28, 2014 11:09 AM
To: info@...
Subject: Code 88 wheels

 

Hello Reboxx.

 

You may be aware that there is currently an extensive thread on the STMFC groups @yahoo about wheel sets and couplers . One part of the discussion is about the fact that many HO scale wheel sets are described by the manufacturer as “code 88” when in fact they are a hybrid, with total wheel width of 0.088” but with equivalent to code 100 flanges, resulting in narrower tread (0.058” vs 0.063” spec) than  a true Code 88 wheel.  There seems to be some agreement that these “near Code 88” wheels perform OK, and several have posted that Reboxx wheels, among others, work fine on standard HO track.

 

Nothing on your website states the dimensions of your wheel sets, except that they are described as Code 88. Can you confirm whether or not your Code 88 wheel sets are true to the NMRA description of Code 88, or are they what seems more common, to be Code 88 width but Code 100 flanges.

 

I will gladly post your response, or you may wish to post it. Here’s a link to the thread:

 

https://groups.yahoo.com/neo/groups/STMFC/conversations/topics/124785

 

Thank you.

 

Tom Hayden

Lakewood, OH