This activity has provided the opportunity to examine several engines from various manufacture brands that were Kato provided models. These include Atlas, Stewart and Kato themselves. This post will document the results of these various tests.
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- 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.
The color key in these charts is the Atlas versions are in green, the Stewart engines are shown in blue and the Kato engine in is purple. The scales of all of the charts are maintained the same with the cumulative and other specific posts. This implicitly will help with how these compare with the others tests.
The scale on this chart shows the wide range of current draw exhibited in HO model train engines. As might have been predicted, the Kato engines all fall near the bottom of this scale. This is interesting, because the Atlas Kato engines were produced over 25 years ago. The Stewart engines have been out of production with Kato drives for fifteen years. The chart does show a current reduction with time. Although the increment is modest, the percentage reduction is impressive. The curl up at 4 volts is typical of a stalled motor and is near the stall current for that voltage. It is interesting that this is present in some of the Atlas versions, but none of the later versions have shown it. This implies a reduced starting velocity for the newer drives.
As has been the case with this testing, when the engine is put on the track, the current draw increases. However the four volt stall condition goes away. This is an interesting phenomena between the track and the roller running measurements.
This chart points out the variation between the three basic production era’s. The newer units seem to draw less current.
There is a larger overall variation in the Atlas versions. As can be seen in the overall list post, these engines are of various model types. The Stewart variation is all F units, F3, F7 and F9. There are some Booster units without a light They are all similar in dimension and weight, although these is some weight variation.
The velocity variation seems to follow what was shown in the current. In this case the Stewart engines seen to be tightly bunched. There is on outlier at 12 volts. These units vary from no use to well used. Like the current, the later units measured lower velocities across the spectrum. Thus falling below a desired range that would run the engine only at 80 SMPH at the 12 volt setting. This typifies what the more recent units have been demonstrating. The focus on power reduction to reduce motor noise for the engine sound symphony has led to a lack of speed capability. This is particularly noticeable at the higher power settings. This is the reason the performance criteria was expanded to debit this speed short fall at `12 volts. Other “new” units fall down much more than the Kato units.
The maximum pull force shows a large variation in the Atlas units and a small er variation i the Stewart units. The newer Kato unit is below an average of the other two sets. With a single sample, that is all that can be said. It will be interesting to see how other Kato units show in these charts.
The larger variation in the Atlas units may be because of weight, or it may be because of deterioration.
The minimum voltage to achieve a sustainable velocity for all of these units is excellent. The variation is well in an expected range.
The minimum sustainable velocity for all of these units is generally between 2 and 3 SMPH. Two of the Atlas units seem to be out liers and will need som further examination to see about their overall health. Most of these units could crawl very slowly in a pulse environment.
The variation in starting velocity shows that the era evolution has not had much impact on the low-speed torque wobble. The is variation in all of the data, but is seems to hover around the same average levels.
Chart 8 is shown in the following figure:
(Plot is currently not available.)
This chart uses the second performance criteria defined in that posting. Even with this adjustment, several of the tested Atlas and Stewart engines are off the chart. The Stewart engines are all hovering near of above the very good to excellent zone. Based on my assessment, none of these engine should be considered suspect. There are three of the Atlas units that are falling low on the chart. These data should be examined in detail to see if further tuning will bring them up into the excellent zone.
To this point, the Kato derived units are exceptional and have to be rated with the best engines being produced for HO model trains.