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The Good the Bad and the Ugly! Athearn SP 4-8-2 MT-4

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Improved mechanical features over prior Genesis steam releases and much better sound also, but a potential time bomb in the locomotive pick-up.

Athearn SP 4-8-2 MT-4

The highly anticipated Southern Pacific 4-8-2 arrived today. Our first impression was favorable. Upon a visual inspection it would seem that Athearn, to some extent, has learned from past mistakes. Some of you will remember the UP F-E-F loco that Athearn released a few years ago. While it was an attractive model it was plagued by a laundry list of problems including a factory installed sound decoder which did not operate well, and a single driving rod set-up which caused significant binding because the rods had FAR too much play. Athearn had run a single connecting rod to all of the drivers which has long been a “no-no” in both prototype and model steam locomotive design.

One connecting rod for all drivers causes problems.

One connecting rod for all drivers causes problems.

The other drawback of this design is that it requires the use of elongated crank pins. This can cause further problems because the long rod can laterally twist on the long pins, causing additional binding.

Far too much play in the rods.

Far too much play in the rods.

Now compare the pictures above to the pictures of the driveline on the new MT-4 below!

3 piece rod means smoother operation! Very little play means minimal binding!

3 piece rod means smoother operation! Very little play means minimal binding!

As you can see, the new model has 3 piece rods, which keep the operation much smoother.

Unfortunately our close inspection of the driveline turned up a much bigger problem. It would appear that Athearn has taken a technological step backwards and reverted to the old “sprung button” pick-up method on their drivers. This method was commonly used by manufacturers like AHM and Rivarossi and has long been a bane to DCC users. The issue is that most of the springs that are used to push the buttons onto the back of the wheels may not hold up if the loco derails and causes a short. A potential high current flow will melt the springs making the loco inoperable! This design leaves the user between a rock and a hard place because trying to increase the size of the spring leads to more friction on the backs of the wheels, which will also negatively affect operation.

Spring-Button Pick-Ups contacting inside of drivers

Spring-Button Pick-Ups contacting inside of drivers

Initially the loco does run well despite this flaw, and the Tsunami sound is acceptable but lacks loco specific features. The chuff sounded like a maraca when we first ran the loco here, upon inspecting the tender we quickly discovered why; despite having a well designed Vanderbuilt tender with plenty of space for a better speaker, Athearn decided to go with a single 1.1”low profile speaker in a enclosure, crudely attached to the roof of the tender. We’re confident that customers with even remedial installation skills could easily convert this tender to use a larger speaker without modification to the tender itself.

The TDS speaker series offers several excellent options that will improve the sound significantly!

Given the low profile speaker that Athearn used we tried to maximize the sound by using the sound decoders built in equalizer feature, we were able to quickly and dramatically improve the sound of the loco by making very elementary changes. We found that the loco sounded best with CV153 set to 3 as opposed to the factory value of 0. We also noticed that when momentum was programmed into the locomotive the chuff sound would start long before the wheels began to turn, this again can be remedied by simple programming. Increasing the value in CV2 to between 7 and 10 seemed to fix this problem, however, when you do this you sacrifice the nice slow start that many steam operators look for. The most troubling issue with the sound was that the chuff response was nowhere near in sync with the motion of the drivers, sometimes giving 2-3 chuffs per revolution (low speed) sometimes giving 6-7 (high speed).

Another interesting, realistic, visual point is the stars on the end of the driver axles that depict the prototype axels. Surprise, a closer inspection showed them to be stickers which came loose with almost no contact, so use care around them!

Paint may have been a better choice!

Paint may have been a better choice!

All in all Athearn has again built a gorgeous locomotive that looks and runs well but may have some problems, time will tell.

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