Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

NMRA gauge: how much is too much?

1724 views
13 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January 2005
  • From: Winnipeg Canada
  • 1,637 posts
NMRA gauge: how much is too much?
Posted by Blind Bruce on Monday, October 4, 2010 3:56 PM

I read about wheelsets being out of gauge more times than not. I have checked most of my trucks with the NMRA gauge and can't tell much difference. If I look VERY closely with my Optivisor, I may have found a few that are closer to one edge rather than being centered in the gauge slots. Is this sufficient cause to adjust? The change might be .003" or .004".

73

Bruce in the Peg

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Monday, October 4, 2010 4:09 PM

There is an allowable tolerance built in to the gauge. If the wheels fit in the slots they are ok. If you have to force it in or it is either too narrow or too wide to actually go in the slot, they need to be adjusted.

                          --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    February 2008
  • 8,877 posts
Posted by maxman on Monday, October 4, 2010 4:27 PM

The NMRA wheel standard shows a back to back wheel dimension of 0.573 inch, plus 0.002 inch, minus 0.007 inch.  This would be for "normal" HO scale wheels.  See: http://www.nmra.com/standards/sandrp/pdf/S-4.2%202010.02.24.pdf  So this means to me that there is 0.009 inch total allowable deviation for min to max.

Note that there is a different back to back dimension if you are using scale of semi-scale wheels.

The way I was told to use the NMRA gauge was to push the back of one wheel against the edge of one of the slots, and then rock the wheelset into the other slot. If it rocked in, then that was good enough.  When I experimented with this, I found that some wheelsets which would fit into the two slots if placed directly into them would fail if tested with the rocking in method. 

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Monday, October 4, 2010 5:04 PM

For all of the hoopla about wheesets being out of gauge, I have rarely encountered this problem, with or without the use of my NMRA gauge.

And I have 42 engines and over 150 cars, both freight and passenger.

Rich

Alton Junction

  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Monday, October 4, 2010 5:11 PM

I found only one axle out of gauge across 18 different types of engines, five different providers, and with over 50 cars/wagons of any description.   But some were tighter than I thought they should be, sort of not quite fitting nicely into the two slots, so I widened those when I could.

The one axle was on a Genesis SD75M, and it may not have been the assembly that caused it.  It may have been the seller.

-Crandell

  • Member since
    August 2004
  • 2,844 posts
Posted by dinwitty on Monday, October 4, 2010 5:29 PM

get me, having done inspection for the club I was in,,,, well say maybe over 400 cars, locos, etc, can you say... AAAAAUUGH!!

in the years of operation you find problems, dirt on wheels, couplers off, maybe some wheels out of gauge..

A car derails and you wonder why everything checks out perfect,...thick dirt on the treads. Rolls right off, the flanges do nothing. Scrape scrape scrape.

 

  • Member since
    July 2006
  • From: upstate NY
  • 9,236 posts
Posted by galaxy on Monday, October 4, 2010 5:52 PM

I don't know. I have yet to check a single wheel set with a NMRA guage and don't have any locos or cars that jump the tracks except at switches through MY own fault for switch misalignment.

I have some really cheap cars, too.

{LOL I have had a train I ran right off the tracks that met the floor going to fast, though- again my fault}

-G .

Just my thoughts, ideas, opinions and experiences. Others may vary.

 HO and N Scale.

After long and careful thought, they have convinced me. I have come to the conclusion that they are right. The aliens did it.

  • Member since
    February 2008
  • 8,877 posts
Posted by maxman on Monday, October 4, 2010 6:21 PM

richhotrain

For all of the hoopla about wheesets being out of gauge, I have rarely encountered this problem, with or without the use of my NMRA gauge.

I believe that the rarity of this problem is a function of whether or not one uses after market wheel sets as well as when a particular model was produced.  I think that after market wheelsets are probably made to a higher standard than what one would find on run of the mill models, such as the older Athearn blue box cars.

And any old timers around will probably remember reading model reviews in MR where the reviewer indicated that one or more wheelsets were out of gauge and had to be adjusted.

  • Member since
    June 2003
  • From: Culpeper, Va
  • 8,204 posts
Posted by IRONROOSTER on Monday, October 4, 2010 6:25 PM

I have never had a problem with a wheelset if both wheel flanges fit in the slots.  That's in both HO and S scale (S scale standards gauge is sold by NASG).

Enjoy

Paul

If you're having fun, you're doing it the right way.
  • Member since
    January 2010
  • From: Denver, CO
  • 3,576 posts
Posted by Motley on Monday, October 4, 2010 7:53 PM

Say you do find a wheelset that is out of gauge. How do you "adjust" it? I see no way of adjusting or correcting wheelsets. Do you just replace them?

Michael


CEO-
Mile-HI-Railroad
Prototype: D&RGW Moffat Line 1989

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Monday, October 4, 2010 8:18 PM

A lot of wheelsets you a 'twist' the wheel on the axle and move it in or out as needed. A drop of CA helps it stay in place. Most diesel locos use some form of split axle arrangment and so are easy to adjust.

                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    June 2009
  • From: QLD, Australia
  • 1,111 posts
Posted by tbdanny on Monday, October 4, 2010 8:20 PM

Motley,

It depends on whether the wheelsets are plastic or metal.  If they're plastic, then they're probably moulded as one piece and can't be adjusted.  If they're metal, then NWSL's puller is the way to go.

EDIT: I'm referring to carriage wheelsets and steam loco drivers.

Working with older brass models, I find that checking the wheel gauge is an essential part of the process of getting them ready to run.  Having said that, I also had to correct 3 tender axles on a brand-new Blackstone K-27.

Cheers,

tbdanny

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

  • Member since
    October 2001
  • From: OH
  • 17,574 posts
Posted by BRAKIE on Monday, October 4, 2010 8:57 PM

Blind Bruce

I read about wheelsets being out of gauge more times than not. I have checked most of my trucks with the NMRA gauge and can't tell much difference. If I look VERY closely with my Optivisor, I may have found a few that are closer to one edge rather than being centered in the gauge slots. Is this sufficient cause to adjust? The change might be .003" or .004".

Bruce,Thankfully our equipment is forgiving as far as wheels or track being slightly out of gauge and at .003" or .004" I wouldn't worry about it since the slop (play?) in the wheels/trucks will overcome such a minor problem.

I have 99.9% derailment free operation at the club and I highly suspect all of my wheels isn't perfectly in gauge.

Larry

Conductor.

Summerset Ry.


"Stay Alert, Don't get hurt  Safety First!"

  • Member since
    October 2001
  • From: OH
  • 17,574 posts
Posted by BRAKIE on Monday, October 4, 2010 9:06 PM

maxman

 richhotrain:

For all of the hoopla about wheesets being out of gauge, I have rarely encountered this problem, with or without the use of my NMRA gauge.

 

I believe that the rarity of this problem is a function of whether or not one uses after market wheel sets as well as when a particular model was produced.  I think that after market wheelsets are probably made to a higher standard than what one would find on run of the mill models, such as the older Athearn blue box cars.

And any old timers around will probably remember reading model reviews in MR where the reviewer indicated that one or more wheelsets were out of gauge and had to be adjusted.

Actually I found the BB wheels gives troublefree performance once they are in guage..I perfer Athearn BB trucks over  most other brands and I simply love their trucks with metal wheels.

As far as reviews-salt please!

Larry

Conductor.

Summerset Ry.


"Stay Alert, Don't get hurt  Safety First!"

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!