All the A, J and late model Y classes used spoked driving wheel centers. This was long after most modern engines were being built with BoxPok or Baldwin disk or Scullin disk wheels.
Does anyone know why N&W stayed with spoked wheels so late in the game?
I note that the C&O H-8 Allegheny, another modern design, also used spoked driving wheel centers.
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Probably because the WORKED, and had no failure issues. Remember, you are discussing drive wheel centers smaller than 70" diameter WITH TIRES. The advanced/increased use of the various disc types and BoxPok drive wheels were primarily for applications exceeding 75" diameters, i.e. MUCH higher operating speeds.
The C&O Allegheny used Union web spoke driver centers, on all orders...IIRC. Not a true spoke oldie.
They must have worked. The J could produce very high speeds with 70" wheels!
I don't think it's entirely true to say that spoked drivers had no failure issues. One of the reasons that disc drivers were developed was to produce a stronger and lighter wheel less prone to failure from stress fractures in the spokes. And they were easier to balance for higher operating speeds.
Recall seeing a photo of a Northern Pacific 4-8-4 with a broken spoke driver.......the entire tread was hanging off the side rod, exposing naked spokes suspended in the air.
The Burlington used boxpok center drivers on their 64" drivered 2-10-4's, when they rebuilt them in the '30's for higher speed freight service to Denver (55 mph max). A bit more interesting was the use of a center boxpok driver on the Burlington's 60" drivered, WW I era 2-10-2's, in an attempt to coax more speed out of those plodding fat-soes! And, these same boxpok drivers had counterweights inside the frame, in addition to the counterweights on the wheel, again to counteract the dynamic augment of all the reciprocating machinery at speed. Burlington's primevil O2 and O3 WW I era 5300-series 2-8-2's also had boxpok center drivers. Presume all of this was to forestall driver failures at higher speeds.
As with most things steam locomotive, the N&W perhaps greatly improved spoke drivers.......better metallurgy?
Kelly Anderson posted:could make them in-house on the cheap, and avoid having to buy outside, proprietary designs.
and low rotational mass, and an "If it ain't broke, why fix it" mindset.
Thanks everyone for your insights. I had my suspicions that it may have had to do with cost, either to purchase the items from the suppliers or to pay licensing fees / royalties to produce them in house. As some of you pointed out "Don't fix that which ain't broken.".
All that exotic metallurgy and design saved steam power ....for about five minutes !
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