I have been told that the BART transit system which uses Indian gauge (five foot six inches) initially selected wheels with a flat profile (like the MTH subways), rather than an angled profile. I am sure there must have been some engineering rationale for this, but I can't think of any.
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BART uses the standard Amtrak wheel profile, with exception that the throat radius is slightly larger. This is a cylindrical rather than tapered tread. This tread profile is used because it provides a smoother ride at high speeds and does not hunt. This Amtrak tread profile can be found in the AAR Wheel and Axle Manual, I do not recall the figure number. This wheel profile has been used successfully at BART for over forty years.
The "Amtrak profile" should be the 1 in 40 profile, developed by EMD many years ago, for higher speeds. The cylindrical tread profile, originally used by the North Shore Railroad on their electrified interurban equipment (90+MPH) on the 1930s, and subsequently by the AT&SF for their diesel units used at speeds over 100MPH, was still used well into the Amtrak era. Sometime in the 1980s, as best as I can remember, Amtrak no longer wanted the expense of having special/different wheel truing cutter heads for the wheel truing machines, so the 1 in 40, wide flange "unipoint" profile was developed and tested. Amtrak still uses the 1 in 40 wheel profile on their diesel units to this day.
Tommy,
I didn’t know that BART used the Indian Broad Gauge. I am originally from India & I find it funny that all the newer metro lines in India (Delhi, Bombay, Madras, Kochi, etc) are built to Standard Gauge & a metro in the US uses the Broad Gauge.
These are just my opinion,
Thanks,
Naveen Rajan
I have been told that the BART transit system which uses Indian gauge (five foot six inches) initially selected wheels with a flat profile (like the MTH subways), rather than an angled profile. I am sure there must have been some engineering rationale for this, but I can't think of any.
Thank you all for your answers. I was unaware that cylindrical wheels were so common and were used on AMTRAK, nor was I aware of the history, or the rationale. I guess there is a trade-off between "hunting" and track damage and wheel damage on curves. President Lincoln was responsible for the four foot eight and a half inch gauge, forcing the Erie to reduce gauge from 6 foot. The BART cars are not that wide, but there is significant more stability. And of course the U.K. retained the seven foot gauge well into the 1890's.
The point came up during a discussion of wheel damage to the tracks on BART on curves due to the same-diameter wheel's.
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