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Current draw

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  • Member since
    January 2004
  • From: Québec
  • 82 posts
Posted by SD40-2W on Tuesday, May 4, 2010 11:34 AM

Thanks Guys for your feedback, it's appreciated.

Michel D.

  • Member since
    November 2002
  • From: Colorado
  • 4,075 posts
Posted by fwright on Monday, May 3, 2010 1:38 PM

SD40-2W

In MR when they review a product like a locomotive they measure current draw at 12 volts (DC) using two terms I do not understand: Slipping and Stalled.

Could someone be kind enough to explain these terms and give exemples.

Thanks,

Michel D.

Most model locomotives (especially HO and smaller) will have their drive wheels start to spin - slipping on the track - before the motor will stall.  Model locomotives with traction tires are a major exception.

Just about all model locomotive motors will burn up if stalled for more than a few seconds.  In the stalled condition, full power is applied to the motor but it is unable to rotate for whatever reason.

Slip current is therefore the maximum current a model will see in normal operation.  If too many cars are added, or the grade is too steep, or similar overload external to the locomotive, the wheels slip and spin, allowing the motor to continue to rotate.

Too much friction inside the locomotive, or locking of the wheels causes the motor to stall.  The stall current is the greatest current a model locomotive will see, and is therefore often used to select a DCC decoder.  This prevents decoder burnout should the locomotive somehow get stalled.  It also means the motor will likely burn out before the decoder.

hope this helps

Fred W

  • Member since
    January 2007
  • From: Eastern Shore Virginia
  • 3,290 posts
Posted by gandydancer19 on Monday, May 3, 2010 1:28 PM

 Slipping means the power is on, the wheels are spinning, but the loco is not moving.  No extra weight added.

Stalled means power is on and the loco is held or pushed down until the wheels stop spinning or turning.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

  • Member since
    January 2004
  • From: Québec
  • 82 posts
Current draw
Posted by SD40-2W on Monday, May 3, 2010 1:16 PM

In MR when they review a product like a locomotive they measure current draw at 12 volts (DC) using two terms I do not understand: Slipping and Stalled.

Could someone be kind enough to explain these terms and give exemples.

Thanks,

Michel D.

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