Dear Allen,
The SHS AF. comp. wheels used the design made popular in the early
70's by Ace MRR Supply who was owned at that time by Walter Graef.
He told me that research had been conducted using the NMRA RP-25 wheel
contour for use on AF track. Unlike the wheels that AC Gilbert Co.
designed in the 40's, the RP-25 has a 3˚ tread which prevents the
truck from hunting for the center (going from side to side) like the
AF 0˚ tread. If you look at a AF train going down a long straight
away you can see the entire train going from side to side as it
travels down the track. Other tread improvements include a filet
between the tread and flange. This helps prevent the wheel from
riding on the edge of the flange. Another is that the bottom of the
flange has a radius. Once a wheel starts to climb over the flange,
this will help keep the wheel on the rail. Walter also told us that
the height of the flange only prevented derailment on stepped on track
where the rail takes very quick dive down. That once a wheel starts
to climb over the rail, the length of the flange did not make a
difference. That is why his flanges were so much smaller (more than
half I think) than the AF wheel and why they can be used with code 100
rail (of course this also depends on the height of the spike head).
Don
On Nov 19, 2010, at 2:26 AM, Allen wrote:
>
> Strangely, I've never tried it. Can anyone clue me in?
>
> I am not referring to an AF wheel, but a Hi-Rail wheel like that
> made by SHS or AM.
>
> Thanks,
>
> W. Allen Evans
> NMRA / NASG
>
>
>
[Non-text portions of this message have been removed]
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