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slow those loco's down

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  • Member since
    June 2007
  • 49 posts
slow those loco's down
Posted by Woofda on Friday, March 28, 2008 10:28 AM

How do you adjust your Dcc locomotives to move really slow?   I have a NCE Dcc System, HO scale.

  • 1. Really slow would be defined as less than 5 scale mph on start in HO scale.
  • 2. Engine starts at a crawl then advances to commanded speed so as not to jerk train.
  • 3. Buy quality engines?
  • 4. Set motor control parameters by changing CV's ?
  • a. Start voltage cv2
  • b. Acceleration cv3
  • c. Motor pwm frequency cv9
  • d. Nce torque compensation dick rate cv116
  • e. Nce torque compensation kick depth cv117

Any ideas would be greatly appreciated.

 

  • Member since
    November 2002
  • From: Colorado
  • 3,959 posts
Posted by fwright on Friday, March 28, 2008 1:20 PM

First of all, a locomotive has to run slowly and smoothly on DC.  DCC control does not improve the running characteristics of a locomotive.  CV adjustment allows you to adjust how you control the locomotive, but it can't turn a poor runner into a good runner.

If you want to improve your locomotive's running yourself:

  1. remove the motor and worm(s).  Does the mechanism roll freely and smoothly on a glass plate?  If not, find the binds and fix.  Often gears will have burrs and flash.  Bearings and gear boxes can be dirty or full of old caked lubricant.  Steam loco side rods can be bent and/or drivers out of quarter.
  2. Can you hold the motor in your hand while it's running, or does it vibrate too much (out of balance or bad bearings)
  3. use the current draw as a measure of how good things are/aren't.  A loco with an open frame motor should get down to 0.6 amps or less running by itself.  Weak magnets, as well as binding mechanisms, can cause high current draws.  Magnets in open frame motors can be easily replaced with rare earth magnets, reducing current draw and increasing torque.  Can motors will draw less current, typically in the .25 amp range for HO scale.
  4. If the locomotive is running properly, is the gearing and/or motor RPMs too high?  Increasing the gear ratio will improve slow speed running, while decreasing top speed at 12 volts (usually a good thing).  For my era and prototype, gearing for a top speed of 45-50 smph helps with low speed performance.

Can't really help with individual CVs.  But a steady creep of less than 5 smph should be achieveable on straight DC in most all locomotives.  Once you have that, fine tuning the CVs to meet your desires shouldn't be difficult.

my thoughts, your choices

Fred W
 

  • Member since
    June 2007
  • 49 posts
Posted by Woofda on Saturday, March 29, 2008 8:42 PM
fwright great post.  What I'm getting is that people don' adjust their loco's  CV's they take what is given.  I noticed from other post that this post is a mystery to most members. I have some friends in the hobby that can extract max performance out a box the loco came in. Just as soon as I learn to do this I'm going to share these technics with the forums members.
  • Member since
    June 2007
  • 49 posts
Posted by Woofda on Saturday, April 5, 2008 10:45 PM
I recently put a QSI chip upgrade into a BLI Hudson and BLI Mike and the low speed response is like day and night. I am really impressed with the QSI upgrade chips. The engines accelerates smoothly and run very well.
  • Member since
    July 2006
  • 3,312 posts
Posted by locoi1sa on Sunday, April 6, 2008 8:02 AM

 Recently I got 2 Stewart switchers and put TCS MC2 chips in with BEMF. I had to turn off the BEMF because the locos started too fast on Speed step 1. I adjusted Dither to just turn the flywheel on speed step 1 and now they run great. Nice and slow. 5 minutes from 1 tie to the next. Sometimes locos run so good that I have to adjust CVs down to get them to run like the prototype. Then you get other locos and have to adjust CV2 to 24+ to get them to turn over and CV6 to keep them from flying off the track. Gear ratios play a big part of speed matching locos I just wish manufactures would standardize or just come close to each other.

   Pete
 

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

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