Aristo 4-6-2 Pacific versions main page

Comparison to the prototype

From Davy Cormack:

The Aristo-Craft pacific is a pretty decent representation of the B&O P7 class. Just a couple of things to point out . The Aristo pacific's drivers scale out at about 72"/73" diameter while the real P7s had 80 inch drivers so the model is slightly out in this respect.Also the sand dome is the wrong shape,should be rounded-oblong not round as per the model .

Otherwise the Aristo locomotive isn't a bad representation of the P7 type as built. The Aristo tender on the other hand is not as per the tender attached to the preserved 5300 ex president Washington. I have researched this extensively ....the tender as modeled by Aristo is correct for one single tender only that was attached to 5304 early on in her life. The Aristo tender has curved bunker sides yes but is quite different from the P7.. 8 wheel tenders that received curved bunkers later in their lives. The "standard" curved bunker modifications involved the tender sides being raised substantially and the water tank rear had an enclosed walled area...the tender attached to 5303 at the museum is of this type ,if you compare it to the Aristo model you will see that it is quite different. If you look at the Aristo tender you will see that the bunker curves start at the top rivet line...this is not the case on the museum tender.
The P7s were greatly modified throughout their lives and no two members of the 21 in the class were identical latterly. All had some detail differences some, slight some major.

In short the Aristo model is a good general representation of the class but isn't accurate for any single loco at any time without modification .


There are 4 versions, the original one was designed in Korea I believe. It was designed in that time of having all the "bells and whistles", some of the G scale toys we have now.

1st generation

  1. puffing smoke with smoke from cylinders (unfortunately the bellows to puff the smoke often failed, as well as the smoke unit itself.
  2. all wheel track pickups, both loco and tender (great feature)
  3. plastic siderods (looked poor and can break, no replacement parts available)
  4. "ok" drive mechanism with long main drive shaft and only 1st and 3rd drivers powered.
  5. No "socket"
  6. firebox lights
  7. fill smoke unit from toolbox on front pilot

Summary: Unfortunately, not a very good runner/puller, drivetrain can have worm slip on shaft, smoke system not reliable, and plastic siderods could break, made in Korea

2nd generation

  1. gearbox same, but different design of drivers, how wheel is locked to axle
  2. Many of the old trim pieces were used on the second version
  3. The Pacific and the Mikado have the same boiler shell
  4. Smoke unit updated to simple heater and fan, stack only, never great, but more reliable

Summary: a bit better, but still has many of the negatives of the 1st generation

3rd generation (introduced 2003)

  1. new type fan driven smoke unit, smoke stack only, good when it worked (see section on Aristo smoke units)
  2. power pickup from drivers and 1/2 tender wheels only (not great)
  3. metal siderods
  4. new "prime mover" gearbox much more robust, but with attendant issues of slipping drivers
  5. "aristo socket" in boiler

Summary: much better smoke unit, gearbox stouter and can find replacements for the individual modules, all drivers powered. Power pickup much worse and may require significant disassembly to improve

4th generation (2011)

  1. Socket moved to tender with changes in wiring to accomodate
  2. a "new" insert in the center of the drivers to help avoid the dreaded wheel slip that plagues all Aristo motive power, makes no real difference.

Apparently, there is a metal bushing pressed into the center of the wheels (before, the pot metal wheel had the taper machined into it directly). What you can see from the outside is that the screw on the axle no longer has a recess to fit into:


At this point, if you buy a Gen 1 or 2 unit, it's used, even if new in the box, there will most likely be problems. Inspect the drivetrain carefully by removing the gearbox cover. Many of these have the worm gear slide on the driveshaft.



Click the links below to go "deeper" into details on individual Aristo-Craft motive power topics

Gen 1 & 2 Pacific  Gen 3 & 4 Pacificprime mover motor blocks



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