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HO Wheel dimensions changed since 1960s?

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  • Member since
    March 2012
  • 50 posts
HO Wheel dimensions changed since 1960s?
Posted by RealGomer on Sunday, August 1, 2021 3:27 PM

I solved my electrical problems on my first layout since 1979 but now I've run into another problem. My rolling stock is mostly from 1966 through 1979 and is mostly Atlas, or Rivarossi. I have a couple Atlas Santa Fe box cars slightly overweight by NMRA standards. They have truck mounted horn & hook couplers. The problem is they derail in several locations. I clipped the downhanging bit from the coupler thinking they were catching on something. Nope. Could it be the cars / wheels were designed when the common stack was Code 100 and I'm running Code 83 track now?

Tags: Code 100 , Code 83 , derail
  • Member since
    March 2012
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Posted by RealGomer on Sunday, August 1, 2021 4:30 PM

I think I may have stunbled on to part of the problem. I used Atlas 1 meter (3 ft) Code 83 Flextrack for 99% of my layout. Where the cars derail is where a 18" radius Code 83 section was installed. I thought at first the cork roadbed had debris on it but the inserted bit is shorter than both sections of the Flextrack. It may only be 1/2 mm but even though the rail ends touch it seems to be enough to cause derailments. Now the kicker. When I run my locomotives (E9's) from the same era or a 1956 Revell caboose over that section they all track as pretty as you please. Confusing, eh wot?

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
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Posted by SeeYou190 on Sunday, August 1, 2021 6:11 PM

Wheel profile has improved from the "train set" wheels of the 60s through 80s.

The specification is NMRA RP (recommended practice) 25. Usually abbreviated as just RP25.

These wheels are excellent, look good, and tend to be much better at staying on the track. They work with code 100, 83, 70, and some code 55 HO scale track.

I use Kadee trucks with RP25 wheels on my Tyco cars.

Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

  • Member since
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Posted by PRR8259 on Sunday, August 1, 2021 11:53 PM

In addition to rail height/profile, one should be careful not to have a horizontal or vertical kink at a joint.

I've played with lots of trains, from those old 1960's/70's rfreight cars up through today and learned there is no substitute for patient trackwork.  

On my current layout, I've laid and relaid horizontal curves a couple times to best suit what I was running at the time.  Some curves have been left alone since original construction, and others have been a challenge at one time or another, depending upon what I'm running (generally big and long stuff).  Through trial and error I've learned that what works well for big steam or even some brass steam does not necessarily work for big 86' box cars and autoracks.  Avoid reverse curves or curves that only have a short tangent between them.  Try to get at least a 9" tangent between reverse curves.

If you have superelevation, be careful not to transition into or out of it too quickly, as some manufacturers' diesels can't handle a fast cross-slope transition.  The trucks will rock and they will derail.

John

  • Member since
    November 2013
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Posted by snjroy on Monday, August 2, 2021 1:09 PM

Hi therel. For sure, if you have rolling stock with deep wheel flanges à la Rivarossi of the 60's, you will hear thumps and see derailments on code 83 track. The old Atlas cars should be OK, unless they are over 60' long, which may derail in tight curves. As mentioned above, trackwork needs to be bulletproof. In particular, watch for track that is not level laterally, that will "lift" the wheels and cause derailments. 

Simon

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    September 2003
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Posted by Overmod on Monday, August 2, 2021 5:56 PM

snjroy
Hi therel. For sure, if you have rolling stock with deep wheel flanges à la Rivarossi of the 60's, you will hear thumps and see derailments on code 83 track.

And yes, to respond to one of early questions, those pizza-cutter wheels ARE smaller in diameter to 'accommodate' the oversized flanges, and putting correct-size scale wheels in will affect the ride height and coupler height.

Ask Mel Perry about drivers on many of his Cab-Forwards!

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