Some facts concerning GE's "Ub" boats. The frames for the U23b, U25b, U28b, U30b, U33b and U36b are the same length. This overall dimension is 60'-2" from center to center of couplers. The overall length of the U18b is 54'-8". The overall length of the Dash 8-40b is 65'-5". The overall length of the B39-8 is 66'-4". The interesting thing from a modeling standpoint is the center to center of the trucks is the same for all except the U18b. From my NS mechanical diagrams: U23B = 36' 2" truck centers with a 60' 2" overall length B23-7 = 36' 8" truck centers with a 62' 2" overall length B30-7A = 37' 10" truck centers with a 62' 4" overall length B36-7 = 36' 8" truck centers with a 61' 2" overall length I suspect the differences are in the slight differences in equipment layout. Chris Toth


>I think the biggest shock of all was discovering, via a failed attempt to
>build a B23-7 from a Rail Popper shell, that all B-7's did not have the
>same wheelbase... or carbody length.  One of those things that clicks in
>your brain as "they are all alike" without ever having been checked against
>empirical data.  Ironically what led me to this was the Overland B23-7
>chassis... the RPP shell overhung the ends ridiculously, definately wrong
>compared to some direct broadside photos I had.  Yet the Overland chassis
>checked out at 36'2" right on the money.  Ended up that the RPP shell is
>something like 2 feet too long... closer dimensionally to a B30-7A.
Andy, it's not that bad.  Here's a repost of my comparison to the three
phases of Dash-7s and the Bachmann and RPP B23-7s.  The Overland chassis is
too short for the RPP's prototype (a late B23-7).
As I mentioned last week, Dash-7 B-boats came with three wheelbases.  I
have confirmed that all the "phase three" Dash-7 B-boats have the 36'8"
wheelbase and the shorter 57'4" frame.
Here are some relevant dimensions:
Phase One (early 77 into spring 79)
length                          58'4"
wheelbase                       36'2"
front pilot to front bolster    11'1"
rear pilot to rear bolster      11'1"
Phase Two (spring 79 to fall 80)
length                          58'4"
wheelbase                       37'2"
front pilot to front bolster    11'1"
rear pilot to rear bolster      10'1"
Phase Three (fall 80 to end of production)
length                          57'4"
wheelbase                       36'8"
front pilot to front bolster    10'6"
rear pilot to rear bolster      10'2"
The Phase Ones use the simpler jacking pad. Phase Twos and Threes have the
flat piece welded to the bottom of the pad (it's actually a piece of 3/4"
treadplate welded on tread side-down).  You can see the differences in
wheelbase and bolster-to-pilot lengths by the positions of the jacking pads
relative to the handrail stanchions on the rear end.  Phase Ones and Twos
have a longer front platform (24") and wider gusset behind the front
stepwell (17.5"), and they have the earlier electrical cabinet (the doors
under the left side of the cab) with the small rectangular panel bolted to
the sidesill in front of the doors.  Phase Threes have the later electrical
cabinet without the bolted-on panel, their front platforms and gussets are
shorter (17" and 12").
I have found no one consistant dimension for the low nose length, but the
Phase Ones and Twos' noses seem to be about 46.5", while the Phase Threes'
are about 45".  Haven't had a chance to measure a high nose yet.
Now what about the models?  There are only two right now, Bachmann's B23-7
and Rail Power's B23-7 shell.  The Bachmann is nominally an early Phase
Two, while the Rail Power is nominally a Phase Three, based on their
electrical cabinets and jacking pads.  Here's their dimensions:
Bachmann B23-7
length  (pilot-to-pilot)        57'5"
wheelbase                       35'11"
front pilot to front bolster    10'9"
rear pilot to rear bolster      10'9"
RPP B23-7
length  (pilot-to-pilot)        58'4"
wheelbase                       36'6"
front pilot to front bolster    10'11"
rear pilot to rear bolster      10'11"
So neither of them are dead on for their particular phases.  But neither
are as far off as I'd thought.
The Bachmann is a tad short, period.  It has some features of an early
Phase Two (jacking pad shape, electrical cabinet, older exhaust stack,
extra grill on the right side under the main radiator grill), but its rear
jacking pad is well foward of the nearest stanchion, which is a Phase One
spotting feature.  It's cab lacks the extra windows, so it represents a cab
that had those windows blanked off after mid-1980.  The cab actually
appears to be based on Bachmann's old U36B cab, since it has the
squared-off headlight housing of earlier U-boats.
In short, if you want to make the Bachmann into an as-delivered Phase One
B23-7, since it's size and wheelbase is closer to Phase One, reshape the
jacking pads so they don't have the little flat piece on the bottom, and
use a Hi-Tech Details cab.  I don't see much point in repostioning the
jacking pads unless you scrathbuild a new frame with the correct wheelbase
for either a Phase One or Two.
As I recall, the Athearn U-B chassis has a 36'0" wheelbase, close enough
for a Phase One Dash-7 and the Bachmann B23-7 as is.  A proper Phase Two
with that rear bolster kicked back a foot will require some modification to
the frame or the rear truck.  A Phase Three is another issue.
I also learned something else about the Bachmann B23-7.  It's not as wide
as I'd thought.  Bachmann's BQ23-7 was about four inches too wide over the
sidesills, and for some reason I thought the straight B23-7 had this same
error.  It doesn't.  So the Hi-Tech cab should fit fine.
D. Scott Chatfield


We've kicked around lots of measurements for EMD stuff on the list, but
I don't remember seeing much in the way of GE data.  Does anybody have
any field measurements, or has it been posted before, and I just don't
remember? (a distinct possibility)...
 Here's what I've found for the four-axle Dash-7s:
1977-early 1979: 58'4&1/4" over the endplates; 36'2" truck centers
mid 1979-10/80: 58'4&1/4" over the endplates; 37'2" truck centers
[I'm guessing on this last one based on the first two and lots of photos
showing that the front and rear platforms on the late Bxx-7 GEs were
closer to the hood than on earlier versions.]
11/80 and later: 57'4&1/4" over the endplates; 37'2" truck centers
David Thompson

I have three GE Drawings as they applied to ATSF Locomotives:
B23-7   36' 8" wheelbase        61' 2" Pulling Faces
B30-7   36' 8" wheelbase        61' 2" Pulling Faces
  This is for #7474-7499
B36-7   36' 8" wheelbase        61' 2" Pulling Faces
All three show a deck height of 70.06"
All show 12' 6" from front coupler pulling face to truck center
and 12' 0" at the rear
Dave Hussey

Well, I hate to contradict "official" GE drawings (yeah, right), but their
draftsmen were obviously a little slow on the updates.  A few months back I
cornered two CSX B30-7s, the 5503 (SCL 5503, blt 3/80) and 5540 (C&O 8258,
blt 6/79).  Both have a wheelbase of 37'2", with 11'1" from the bolster to
the front pilot plate, and 10'1" to the rear pilot plate.  I didn't think
to measure the distance out to the pulling faces.  These measurements jive
with Thompson's listing for units built from mid-79 on.  The B36-7 drawings
in RMC show different bolster-to-pilotplate dimensions.  I'll have to
corner a CSX B36-7 and report on it.  I don't think the RMC drawings are
correct, especially the front platform and nose.
D. Scott Chatfield

Interesting... all the same (no B30-7A's).  I wonder how the Southern B23's
fall into this date range.  I have drawings showing the B23-7 at 36'2"
which is how the Overland B23 chassis measures out.  Knowing Southern, they
bought them in several batches and probably had both wheelbases.  I'm
pretty sure the Southern B36's are 36'8", it's the B30-7A and 7A1 that are
the weirdballs.  This is compounded by the fact that BN's A and A1 units
are cabless yet not given a different model designation... Southern's are
all A1's with cabs, and according to my drawing, have a 37'10" wheelbases
as do the BN's but the A's (not A1's) may be different.
The NS roster diagram book is really useful... shows them all at 36'2"...
shop guys can make some of the same erroneous assumptions as modelers I

Here is what my NS mechanical diagram book lists for the NS units:
60' 2" -- overall over pulling faces
36' 2" -- truck center to truck center
12' -- truck centers to end of coupler
9' 4" -- axle to axle on truck
62' 2" -- overall over pulling faces
36' 8" -- truck center to truck center
13' -- truck centers to end of coupler
9' 4" -- axle to axle on truck
62' 4" -- overall over pulling faces
37' 10" -- truck center to truck center
12' 6' - rear (short hood) truck center to end of coupler
12' - front (long hood) truck center to end of coupler
9' 4" -- axle to axle on truck
61' 2" -- overall over pulling faces
36' 8" -- truck center to truck center
12' 6' - rear (short hood) truck center to end of coupler
12' - front (long hood) truck center to end of coupler
9' 4" -- axle to axle on truck
Chris Toth

Regarding the measurements listed in the NS mechanical diagram book:
First, only the U23Bs with the AAR-B truck have an axle spacing of 9'4".
All the rest of the Southern B-boats rode on FB-2s, with a 9'0" wheelbase.
Second, the later B23-7s and all B36-7s have the 37'2" wheelbase.
Third, the B30-7A1s are longer than the B23s and B36s.  The extra length is
taken by the foward-mounted equipment blower, and shows in the spacing of
the stanchions and the length of the roof plates behind the cab.
BTW, NS just calls the 3500s "B30-7A", but they don't have any early
B30-7As to contrast them to.  The first B30-7As were built for Mopac and
are the same length as the late B23-7s.  The BN has two distinct groups of
B30-7As, the first have the blower and dynamics in the rear like a normal
B23, and the second have the blower and the dynamics up front.  I call the
first group "B30-7AB", and the second "B30-7A2B".
GE model numbers suck.
D. Scott Chatfield

The U23-28-30B/C all use the same bodies, doors and everything else
but HP difference. It would not be economical for GE nor anyother
manufacture to remove doors for a different model since all the
components are in the same location. A GP38 and GP40 are exactly
alike body-wise except for fan configuration and smaller radiator on
GP38 since it's minus one fan. GP38 even has the GP40's turbo blower
duct on the left hood side even though it's not turbocharged.
Jerome Rosenfield

I hate to disagree with you, but they are not all the same.  GE's
practice was to release the next model in the previous models carbody,
and then the carbody would catch up to the model.  For example, early
U-28-B's were released in older late model U-25-B's carbodies until the
28-B's got there own.  P&LE's were a good example of this.  A photo is
on page GE 168 of "THE SECOND DEISEL SPOTTER'S GUIDE" published by
Kalmbach.  I believe that this book is out of print by now.  Back to the
subject, early 30-B's were again released in late model 28-B's carbodies
until maybe the phase two came out of the 30-B's.  The 23-B is a carbon
copy of a late model 30-B externally.  The only difference is the power
plant, the 23-B having only 12 cylinders as compared to the standard 16
on a 30-B.  Yes the Athearn model of the U30B is a good start for your
23B. I dont think that any work is needed to the body, add details and
paint it and you'll be done.  One note, an easy way to determine 33B's
and 36B's from the rest of the U-Boat series is look for the wings on
the end

Mark & Cynthia
S.A. McCall