MPH?

[TVRR]

Was playing with an older Concor 4-6-4 (1975ish) today that got worked over a couple of years ago with new motor and long Bachmann tender. It will now do 2 ties per second on level track with no jerking or hesitation. What does this scale out to in MPH?
 

[wcfn100]

Depends how far apart the ties are.

N scale ties are generally wider than prototype.  But if you assume maybe 24" -

24 * 2 / sec
48 * 60 (min) * 60 (hour)

172,800 / 12 (feet) / 5280 (miles)

2.73 mph.

Somebody check that. 

Jason

[TVRR]

Guess I should have specified Kato Unitrak. Thanks for satisfying my curiosity, the Bachmann 2-8-0 motor has made all the difference with this 1st model's performance. Stuck a Digitrax DT123 in it too which may help. It's fun to run really old stuff that runs right.
   

[thomasjmdavis]

Measuring Atlas C55, 2 ties (plus 2 spaces between ties), I get .283" which scales up to just over 45".  So, I think your math is correct, but the "variable" is much larger than 24.  Still, 5-ish MPH is pretty good.  A prototype Hudson probably did not crawl either.

45x2/sec= 90
90x60x60=324000 inches/hr
324000/12= 27000 feet/hr
27000/5280= 5.11 miles/hr

Of course, the above assumes I read my very inexpensive caliper correctly.  And my Atlas C55 track is probably 10 years old or thereabouts.

Measuring Kato Unitrak, I get .427" over the same measure (2 ties plus 2 spaces)

[mmagliaro]

This made me wonder... just how slow could a real Hudson move?
I found a YouTube vintage NYC video of one moving very slowly , and could count 1/2 driver revolution in 8 seconds, which means 1 revolution in 16 seconds.
I know... not super-precise.

79" drivers. * PI = inches per rev.    / 12 / 5280 = .003917 miles per revolution
1 revolution in 16 seconds -->   .003917/16  miles per second, * 3600 =  0.881 mph.

A later bit of the video shows them moving around at 4 seconds/rev, noticeably faster, and that would be about 3.2 mph.

So yeah, they could crawl pretty well.
Here's the video I used:

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[nkalanaga]

They could crawl, when running light, or starting a train.  A steam loco wasn't good at pulling at very low speeds, as it developed more power as speed, and steam consumption, went up.  tractive effort was constant, as long as the pistons, and loco, were moving.  "Any train a steam loco could start, it could pull at speed."  But starting from a dead stop is very difficult, which is one of the reasons draft gear has slack built in.

An electric or diesel-electric (and probably -hydraulic) is just the opposite.  It develops maximum tractive effort when starting, so can crawl very nicely.  The limit there is motor heating, which limits how long it can pull a heavy train at very low speeds.  "Any train a diesel can pull at speed it can start".  But the only limit on how much a diesel can start is the physical tractive effort (wheel slip).  It may not be able to go very fast with what it starts!

[davefoxx]

But starting from a dead stop is very difficult, which is one of the reasons draft gear has slack built in.

Mind blown!  This makes so much sense, but I never thought about it before.

Thanks,
DFF