Do we need a current day BRMSB?

[martin_wynne]

Setting the wheel profile and back-to-back:

 

 

 

[Pacific231G]

Good find Martin.

This one is even more fun.

https://www.youtube.com/watch?v=c1d3tyQgYxE

I can't see those flanges lasting too long if loaded wagos are running on their rims over frogs. His wheels reminded of some of the older Jouef pizza cutters I replaced long ago.

What's rather fun with these videos is that you can amost imagine the original eigheenth century evolution  of "edge-rail" railways going through these stages. 

 

Edited May 13, 2022 by Pacific231G

[Ravenser]

On 01/05/2022 at 16:58, Ravenser said:

 

 

[The NGS manual ] is a substantial document with lots of practical advice . Not rocket science, but useful reference for the inexperienced.

 

Section 10 Miscellaneous , contains a section headed Standards.There is a wheel/track datasheet with a heading note:

 

Quote

Where 2 sets of figures are shown, the first represent the old 'coarse ' standards for N. Figures in brackets show the newer NMRA standards. Bachmann, while not adopting the new standards completely, moved very much closer to them when they took over Farish, as did Dapol when they erntered the N Gauge market. Even before this many wheels were finer than the old standards

 

Then there is a page diagram showing loading gauge and clearances, followed by tables showing the numbers for BR and SNCF

 

That's it. There is no reference to a standard for couplings or NEM pockets

 

I get the strong impression that NGS have simply opted out of standards as an issue. (That perhaps made sense when you had just one manufacturer, Farish). Neither of the major RTR manufacturers is adhering to either of the sets of figures published, and I've no idea what the situation is for smaller players, or how Peco track compares with the standards. The NGS seem to have had no hand in the "newer standards" they list

 

Effectively there don;'t seem to be any real standards for British N.

 

One comment on the "new" NMRA standards. The min B2B is quoted as 7.54mm. The max checkrail span is quoted as 7.52mm 

 

That gives a total clearance between wheelset and check span , at extremes, of 0.02mm , or 0.01mm per side.

"Hair's breadth " doesn't seem to cover that....

 

The check flangeway on a Peco code 55 point appears to be between 0.686mm and 0.711mm

 

The crossing flangeway is in excess of 0.864mm, and is probably about 0.95mm  (over 0.864mm. I had to use two leaves of the feeler gauge put together) This suggests the check span is about 7.35mm

 

The "old" N gauge standard was 1.1mm flangeways and 7.2mm B2B

 

Some apology may be needed flor resurrecting this thread, but there is some unfinished business I can now finish .

 

The post above gave some key figures for N Gauge track, but those may require correction . Since the wheels and the track are two halves of a matching system , we also need the wheel data

 

This I now have , having measured various items bought for my small N gauge project.

 

All figures are given as B2B / wheel thickness / flange thickness.

 

The respective standards are:

 

Old NEM                      7.2mm B2B / 2.032mm wheel / 0.508mm flange

New NMRA                 7.54mm min B2B / 1.8mm min wheel / 0.508mm flange   

 

(Items starred were bought in 2007-9; other items are 2022 purchases)

Farish:

VBA van *                     7.30mm B2B / 2.0mm wheel / 0.56mm flange

Class 04 *                     7.26-7.32mm B2B / 2.20-2.24mm wheel /0.60-0.56mm flange

TTA                                7.28-7.3mm B2B / 2.02-2.00,mm wheel /          ? flange

TEA                                7.26-7.30mm B2B / 2.0mm wheel / 0,52mm flange   

Class 57 *                     7.38-7.46mm B2B / 2.04mm wheel / 0.52-0.56mm flange

 

EFE:

JIA                                  7.48-7.54mm B2B / 1.80mm wheel / ?? flange

 

Revolution:

IPA                                 7.36-7.40mm B2B / 1.80-1.82mm wheel / 0.56mm flange

 

NGS Hunslet:               7.48-7.52mm B2B / 2.00-2.02mm wheel / 0.52-0.55mm flange

 

Dapol:

Silver Bullet                  7.46mm B2B / 1.80-1.84mm wheel / 0.54-0.56mm flange

VTG Hood   *                7.40-7.44mm B2B /  2.00-2.08mm wheel / 0.52-0.56mm flange

JWA Falcon                   7.40mm (3) 7.48mm (1) B2B / 1.82mm (7) 1.90mm (1) wheel / ?? flange

Class 66 *                     7.54mm B2B / 2.20mm wheel / 0.32-0.38mm flange

 

 Two things are immediately obvious:

 

- there is no clear consistancy in wheel standards between different items produced by the same manufacturer at the same time , never mind between manufacturers,   or between items made by the same manufacturer at different times

 

- none of the wheelsets match either of the published standards . The EFE JIA comes closest , as it is near the "new " NMRA standard

 

Since all the items run through Peco code 55 points, I suspect the flangeway values for code 55 must be 0.7mm - check flangeway / 1.1mm crossing flangeway