Speed matching
If you want to run your DCC locomotives together in a consist, you need to be sure they will go the same speed at the same Digital Command Control speed step. Speed matching involves programming your locomotives so they can run together smoothly. But before you adjust your decoder CV numbers, you need to be able to accurately measure the locomotives’ Mph speed and also know the CV Decimal numbers that will produced these results at Start, Mid. and Max.
Speed Traps
60 Mph is 88Ft per second. In 6 seconds you would travel 528 Ft. A Speed Trap could be set with start and stop sensors at 528 Ft. If the measured time from the sensors is less than 6 seconds, then you are speeding. The measured time in seconds becomes the record of your actual speed in Mph. Then in N scale this is 528/160 = 3.3 Ft in 6 Seconds, and in HO scale 528/87 = 6 Ft in 6 seconds.
Fixed distances and a stopwatch
Speed Traps N Scale HO Scale smph = (6.0 sec. / Time, sec.) x Speed Trap Mph
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120 Mph 6.6 Ft. in 6 Sec. 12 Ft. in 6 Sec. smph = (6.0 sec. / 4.8 Sec.) x 120 Mph = 150 Mph
60 Mph 3.3 Ft. in 6 Sec. 6 Ft. in 6 Sec. smph = (6.0 sec. / 5.3 Sec.) x 60 Mph = 68 Mph
30 Mph 19.8” in 6 Sec. 36.4” in 6 Sec. smph = (6.0 sec . / 6.4 Sec.) x 30 Mph = 28 Mph
6 Mph 2.0” in 6 Sec. 3-5/8” in 6 Sec. smph = (6.0 sec. / 7.2 Sec.) x 6 Mph = 5 Mph
3 Mph 1.0” in 6 Sec. 1-7/8” in 6 Sec. smph = (6.0 sec. / 4.5 Sec.) x 3 Mph = 4 Mph
Scale RAILS Aug. 2008 pages 26 - 29
Circle of track and a stopwatch
By using Atlas 11 radius snap track, anyone (who wanted to) could build their own speed matching track, Using Atlas 11” radius snap track, it is a fixed, consistent diameter loop of track for testing.
11 inch radius circle of track = 69.12 inches (2Rx3.14)
Completing this circle of track in 9 seconds is 70 Mph for N scale.
Speed Traps N Scale Distance smph = (9.0 sec. / Time, sec.) x Speed Trap Mph
140 Mph 139.12” in 9 Sec. 2 Circles smph = (9.0 Sec. / 8.4 Sec.) x 140 Mph = 150 Mph
70 Mph 69.12” in 9 Sec. 1 Circle smph = (9.0 Sec / 9.3 Sec.) x 70 Mph = 68 Mph
35 Mph 34.56” in 9 Sec. 1/2 Circle smph = (9.0 Sec. / 11.3 Sec.) x 35 Mph = 28 Mph
17.5 Mph 15.78” in 9 Sec. 1/4 Circle smph = (9.0 Sec. / 5.6 Sec.) x 35 Mph = 28 Mph
3 Mph 1.5” in 9 Sec. Lg.= 1-½ inches smph = (9.0 Sec. / 6.8 Sec.) x 3 Mph = 4 Mph
http://capitolcityntrak.org/speed_matching.htm
electronic speedometer
“Train Speed” by TDP & Associates, Inc. can measure smph accurately to 150 Mph. It has two photo cells with can make a speed trap for any scale. It is designed for control panel or façade mounting.
http://www.trainspeed.com/TrainSpeed1.htm
“Bachrus speedometer” MTS-DCC50 for Decoder Pro, allows measurement of scale speed of locomotives while running under DCC control. The locomotive's wheels rest on a set of ball-bearing-equipped running stands. One set of rollers, called the reader, is connected by a wire to a portable console that reads out the locomotive's scale speed, and other information.
http://www.bachrus.com/speedometer.php
http://www.youtube.com/watch?v=kPLiJyZ21fk/url]
Speedometers are so accurate that you never get the same Mph display at full speed forward and full speed in reverse. (Motor friction.) This is why I plot my Mph speed data as “Ave. Mph”.
Robert Frey 5 Jan. 2011 [url=link] http://bobfrey.auclair.com
Website: http://bobfrey.auclair.com
Very helpful, and good links, thanks for putting this together Robert.
Eric
I'm kinda likin this stuff
I have the trainspeed product. Haven't hooked it up at the club yet but have seen them work. They do work as advertised.
Springfield PA
The Bachrus Speed Ometer is now running with JMRI 2.11.2 This is part of the JMRI Bachrus speedometer program. The JMRI 2.10 is the present working version.
Robert Frey
Robert Frey The Bachrus Speed Ometer is now running with JMRI 2.11.2 This is part of the JMRI Bachrus speedometer program. The JMRI 2.10 is the present working version. Robert Frey
Does it matter what sensors you use? How do you get the sensor info to the computer? I'm using a rrrcircuits USB/Loconet interface.
With your DCC Locomotive turning it’s wheels in the test stands, the Bachrus Speed Ometer can put it’s Mph information at all speed step into a JMRI file. http://www.bachrus.com/ The data in this JMRI file is still being work on by the JMRI experts. This is being done in Test version 2.11.2 of JMRI/DecoderPro. Some of the changes involved are quite extensive. They may require a certain amount of experience before they are working well. Therefore, this test version should be considered experimental.