My goal is to do a limited, but meaningful tests on every HO engine I come in contact with. In the past that approached several hundred a year. These ran the range from low-end DC models to high-end DCC models. It is my intention to present this data in meaningful sets. I also think it will be interesting to present a cumulative summary of all these tests. This post will document these results. As time and testing progresses, then these results will be updated as appropriate.
This post is a companion post with the List of Engines Tested post. The Engine type, manufacturer and other details are presented there.
The initial data will be for engine only level surface testing. As the facilities are put in place, the grade and car load variations will be added.
Initially, five basic functions will be presented:
1- current draw vs voltage with the engine operating on rollers
This will give a stable current level at any voltage. It will imply the engine health variation.
2- current draw vs voltage for the engine only operating on straight and level track.
3- scale speed vs voltage for the engine only operating on straight and level track.
4- maximum pull force for each engine tested.
5- the variation of normalized scale speed at a given voltage. This is indicative of torque wobble, either from the motor or induced by deterioration issues.
After several variations, the normalized velocity variation is not sufficient to discriminate good and not so good engines.
For that reason, a different set of plots were identified beyond figure 1-4.
5- voltage at minimum sustained velocity. This is the voltage setting that is required to start the engine from dead stop and achieve sustained movement. This is a constant DC voltage, no pulse wave at all. This is a bar chart, one bar per engine.
6- the minimum sustained velocity, SMPH
7- the variation in the minimum sustained velocity, as defined from three runs.
8- the current level at the minimum sustained velocity.
And based on the discussions in the Engine a Health post a critical chart is:
9- the Performance criteria parameter for each engine
This shows the wide range of current draw exhibited in HO model train engines. At first blush, one could assume the high current draw are the oldest and the low current draw are from more recent engines. This is an over simplification of the reality of the results. Some of the lowest current levels come from the oldest engines. This curve is thought-provoking, and requires further understanding.
The velocity variation is quite large. Again, it is not a straight forward as one can imagine.
Chart 8 is shown in the following figure:
(Plot is currently not available.)
Engines with a parameter value of 40 or more should be considered very good. Engines with a value less than 5 are either poor or sick. Most, but not all, of these engines have been fully tuned, so there place on this chart is the best it can do. Another engine of the same manufacturer and type will likely fall out still a different value. This is discussed in specific type posts.
In the tuning posts certain features are defined that can take an engine from the poor region to the very good region. Some features that are commonly used are seen to be very detrimental to performance.
Other functions are showing merit and may be included in the next revision.