Re: Limiting factors for speed of a steam locomotive

Russo Loco Wrote:
-------------------------------------------------------
> Philip et al -
>
> I vaguely remember an old rule of thumb that the
> top speed in miles per hour is approximately 110%
> of the driver diameter in inches, so a K-36 should
> max out at 44 × 1.1 = 48.4 mph (about 50),
> and #4449 or #844, etc., should max out at 80
> × 1.1 = 88 mph (about 90).   I remember
> riding across Wyoming behind #8444 one November
> day in the early sixties and clocking off milepost
> after milepost at 40 seconds each — exactly
> 90 mph.

I've read that the 110% guideline is pretty accurate in the mid range. Large drivers have more room for proper balance weights, so can run faster than 110%. Small drivers are harder to balance.

Bruce