Model Railroading > Intermountain's 2nd run of HO scale SP AC12's: a review

All,
I received one of Intermountain's new (2nd run) SP AC12s today. It was No. 4287, "straight" DC, without sound. It was in a "goodie box" from Caboose Hobbies in Denver. Here's what I came up with from initial setup and operation:

(1) The injector piping was broken off the injector upon arrival. A quick dab of ACC solved
that problem.

(2) Initial test runs on a yard tangent in the layout (three feet of level track) indicated
that the loco needed a good lube. I accomplished that per their instruction sheet using
high-quality lube. The mechanism was tight but smooth; it will need a good break-in.

(3) I next put No. 4287 on a piggyback train and sent it up the 2.2% grade on my Donner
mainline. The minimum radius is 34 inches. I noticed that No. 4287 was "bogging down" on the
curvature and could not pull the same train that an AC 12 from IM's first run
could accomplish. I watched No. 4287 very carefully and noted that the second axle on the
pilot truck was riding up against an air tank on the engineer's side. That caused the loco
to lose traction and bind. About five minutes of effort with a Dremel tool took off about
0.040 or so from the bottom of the air tank and allowed for some vertical travel on the
pilot truck. That solved the slipping and binding problem. I did not have that same problem
with No. 4275 from IM's first run.

(4) The headlight on No. 4287 is orange; I liked the "yellow glow" on No. 4275 better. That is
based on videos of real-life locos. Of course, that is a just personal opinion.

(5) Current draw for my well-broken-in No. 4275 was 0.12amp at about 15 volts for this train on
the 2.2% grade, 34" min. radius; No. 4287 drew about 0.40 amp. for the same train on the
same hill after I fixed the front truck-air tank interference problem. A good break-in
on the former should solve this excessive current draw issue.

(6) The detail on No. 4287 is like that of No. 4275: something short of fantastic.

(7) Intermountain has addressed the "slow-running" issues of the first run; indeed, this loco
may run "too fast" for some, myself included. On the serpentine, continuous grade
trackage of my layout, the slow-running of the first run AC12's was not a problem at all.
On a club layout, though, the "more-normal" speed of No. 4287 should be right at home.

So, there you have it, information from a first glance at a member from Intermountain's second
AC12 run. The characteristics of the first run AC12s forced me to have to "clean up" my trackage,
especially the side-to-side cross level. That was a good thing. I'm glad I did that, because in the process I solved a bunch of other derailment issues. With the new AC12 there were none of the derailment problems I had with No. 4275 from the first run, hopefully due to my "cleaning up my act".

Am I happy with the new AC?.....you bet. And, contrary to those who had lots of driver problems with the first-run engines, my member of that first run is still running very well, although
slowly.....(fingers are crossed!).

Any thoughts?

Rich Farewell, Arvada, Colorado.

Good report, any photos?
Todd Montgomery
Eugene OR

Todd,

I wish that I had photos to share, but I've never taken the time to shoot images of the layout or the IM locos on it.........but, sometime in the future, when I switch to digital.....maybe!

Thanks for asking, though....

Rich

You really don't need a full SLR system to do digital work. In fact the small little P&S digital cameras with a limited zoom are sometimes the best for model work since their small sensors allow for more depth of field. Go find a 6mp camera with a 3x zoom lense and a built in flash, used even. It will be useful for models and any number of number of things. If you want to sell something online, you can take some pics and send to potential buyers and such. Digital cameras can be a very useful tool to have around.

Ted Curphey
Ontario, OR

Rich;

With speed increase did you notice any change in pulling power? (more or less)

Regards

Jere Ingram

Jere,

I did not notice any change in the pulling power once I added clearance between the front truck and the air? tank under the cab. That allowed the full weight of the new loco to be on the rails and full tractive effort to be exerted.

However, when I stopped the train on the 2.2% grade to look at the running gear (it is at eyeball level at that point) and tried to restart it, it was difficult to start it slowly and smoothly; it tried to "jackrabbit" and spin. The slow-speed gearing of the first-run AC12, however, made starting trains on a grade a joy to accomplish.

I think the limiting factor for both locos as to max tonnage possible is wheelslip. The train I used is just about at the wheelslip limit for both locos and I can't tell a difference between them at this point.

Hope that helps.....

Rich

Haven't seen either release yet but the gearing/speed issue in interesting. Most of the AC's could run about 50mph but were balanced mostly for about 25. reason for this is that their primary purpose was Donner pass where they would be running slow hauling trains over the hill. Check out the recent Classic Trains issue (?) for this information. It is a special issue about the Malleys.