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Scale Speed II

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  • Member since
    October 2004
  • From: Colorful Colorado
  • 8,639 posts
Posted by Texas Zepher on Sunday, December 1, 2013 12:36 PM

SCOTT SCHNELL
NOW, does it harm either the engine or DCC control to operate at 20 on a 128 step control?  Does it harm DC power packs or engines to operate at 15% of power control?

Does definitely not harm the DCC control nor a DC power pack to run at low power outputs.   Engines might be a different issue. Usually if the motor is turning it will not be harmed.  However, there is the possiblity of over heating if it is drawing more current than it is designed to.   To know this one would need to know the "max" current of a motor and measuring it while it is running at the low speed to see if it is pulling more than what it is designed for.   Another way is just to touch it after a run.  If it is running hot try a different speed, less load, or less weight on the loco so the wheels will spin when it reaches its max current draw.

[qutoe]if we operate our trains too fast, what speed do we operate them at?  Curious again!  I am trying to keep speed down and to train my mind to see the speed I'm running at as normal.[/quote] One thing that helps me is to go and watch real trains run by.  Then go to the layout and get down at eye level to the trains and really close just like I am watching the real ones.  That gives me a better idea of how "fast" the model is going than looking at them from an "airplane" view 3' or 4' away, or worse across the room.

  • Member since
    July 2006
  • From: North Dakota
  • 9,592 posts
Posted by BroadwayLion on Wednesday, November 27, 2013 9:14 AM

Scale Speeds seem so slow! A 600' long subway train takes 12 - 18 seconds to enter a station (1:1 scale in NYC), and it SHOULD take 6-9 seconds for my 300' train to enter one of my stations. It does this in under 2 seconds.

LION made a table based on a 300' train. Does not matter scale. I can stand at the window and time a BNSF coal train or at the table and time a subway train. I have my trains down to about 35-40 mph, which is what these prototypes used to do. Today's subway trains seldom get above 30 mph. With voltage that low, I get a lot of stalls on my layout. I will install boosters on the upgrades, maybe then I can lower the base speed somewhat.

Sometimes the trains look like they are crawling. But then that *is* what the prototypes do.

ROAR

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

  • Member since
    February 2005
  • From: Southwest US
  • 12,914 posts
Posted by tomikawaTT on Saturday, November 23, 2013 5:21 PM

It won't harm your traction motors to run at something below their maximum rated voltage, whether analog DC or whatever waveform the decoder feeds to your motor via DCC.  Trouble shows up with either overvoltage (and associated scale speeds measured in Mach numbers) or overload - the motor stops turning with power on.  To prevent overload, make sure the wheels keep turning.

In HO, one real foot per second is close enough to 60 scale MPH to be within recognized speedometer tolerance.  A little faster, 69 MPH, is the usual speed limit for fast freight on most Class 1 rail routes, and others maintained to top-quality standards.  Speed limits are reduced as the load-bearing capacity and quality of maintenance deteriorates, down to as low as 10 MPH on poorly-maintained track.  Geography also plays a part.  Trains climbing a mountain won't maintain track speed unless they are grossly overpowered for flatland running.  Curves limit speed - the recently completed track in New Mexico's Abo Canyon is speed limited by curvature to 40 MPH.  If our model curves were 1:1 scale most of them would be restricted to 15mph or less.

To determine how close you're coming to the speed you want, just remember that one full-size inch per second equals five scale miles per hour.

One thing to note.  Scale speed doesn't change with the use of a fast clock.

My own layout (1:80 scale) is based on a prototype that ran up a canyon, following the curves of the river at the bottom (and the Kiso river had, and has, more curves than a Hawaiian Tropic competition!)  Maximum track speed on tangents (found only in long tunnels) is 70kph.  Curves are marked for 40 or 25kph with square black numbers on yellow signs.  My speed controls are NEVER, EVER notched up to anywhere near full power.

On the other hand, the d'raiba of a full-scale D51 class 2-8-2, faced with the 2.5% upgrade on that line, would need full throttle and a helper to come somewhere close to the 40kph curve speed limit.

On the Norfolk and Western, back in the mid-'50s, a coal drag with a pair of Ys on the point and another helping at the rear would have to use full throttle and sand on all three locos to climb the Blue Ridge - at 10 MPH, filling the sky with steam, cinders and thunder.  Today the difference is that there are only twelve drivers under each unit, and a lot less steam and cinders in the exhaust.

One final thought.  Running at scale speed makes any layout seem bigger.

Chuck (Modeling Central Japan in September, 1964 - at appropriate scale speed.)

 

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Saturday, November 23, 2013 4:47 PM

SCOTT SCHNELL

Thanks for the replies - answered my questions.  NOW, does it harm either the engine or DCC control to operate at 20 on a 128 step control?  Does it harm DC power packs or engines to operate at 15% of power control?

if we operate our trains too fast, what speed do we operate them at?  Curious again!  I am trying to keep speed down and to train my mind to see the speed I'm running at as normal.

 

Calculating speed is very easy Quite surprised you were not aware of this. Simple math.

 

http://home.cogeco.ca/~trains/rroperat.htm

The way you control not important really. Too fast and they fly off the track if you are wondering. Damage when they hit the floor.

Rich

 

 

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    November 2013
  • 11 posts
Scale Speed II
Posted by SCOTT SCHNELL on Friday, November 22, 2013 10:39 PM

Thanks for the replies - answered my questions.  NOW, does it harm either the engine or DCC control to operate at 20 on a 128 step control?  Does it harm DC power packs or engines to operate at 15% of power control?

if we operate our trains too fast, what speed do we operate them at?  Curious again!  I am trying to keep speed down and to train my mind to see the speed I'm running at as normal.

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