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Brown Box Era HO-Scale Trains
SD-24 Diesel Locomotive
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TYCO's SD-24, introduced in 1977, strongly favors ATLAS' SD-24 model. Though
there are some differences, the TYCO model does not include a winterization hatch over one of its back radiator fans
as the ATLAS does, one might guess that TYCO supplied its Hong Kong builders with an example of the ATLAS SD-24, produced
in Austria by Roco and first sold in the USA in 1975, and they simply made a few modifications on the original unit.
In
its first catalog appearance, the SD-24 models displayed are all ATLAS locos. This fact can be spotted by noting the grab
irons running up the nose of the short-hood, the wider more correctly spaced trucks, the fuel tank, and the previously
mentioned winterization hatch on one of the roof fans, and most noticeably the properly filled-in front pilot, that TYCO opens
up to allow the talgo coupler to swing freely.
TYCO's Rio Grande SD-24 model may have two paint variations. Examples
I have reviewed are printed with a light yellow coloring for the stripes, cab number and 'Rio Grande'
lettering. The catalog entries, beginning in 1982, show a darker orange-gold color and the stripes running up the model's
front end don't extend beyond the base of the number boards. The lighter yellow version SD-24 stripes extend to
the top of the unit on both ends.
It should also be noted that the SD-24 in later production examples
differ from its initial appearance. Originally, TYCO offered a squeezed in length, but prototypically correct appearing truck.
Late versions offer the truck found on the Super 630. The front pilot is also missing the bottom base under the coupler. It
seems the different truck causes the unit to ride a bit higher and therefore created clearance problems for the front coupler.
Though the image is rather dark, you can see that the Rio Grande SD-24 pictured here is this late version with the Super 630
trucks and has more open space below its fuel tank than the early version Chessie System model and is missing the bottom frame
on its front pilot. Either Rio Grande SD-24 model however carries the cab number 5210.
TYCO's SD-24 model makes
its last catalog appearance in 1986. By the 1983 catalog, the SD-24 is reduced to a single appearance in the
Diesel Locomotives section and remains the same through the '86 catalog. Only the Rio Grande example is displayed
between 1983 and 1986.
TYCO's "Comin' Round The Mountain" train set is the only time the SD-24
serves in train set duty, making for rather limited exposure for this model. There are no known SD-24 models produced
by TYCO for its Canadian or Australian lines. TYCO also never powered any known promotional train sets with an SD-24
model.
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Burlington (No.239-13)
TYCO's Burlington SD24 is cataloged from 1977 through 1981. Most catalog pictures
used by TYCO appear to be the 1975 Atlas SD24 model. This Atlas model substitute is quickly spotted by
its solid front pilot, the TYCO SD24 included open pilots for talgo truck couplers.
Tony Lucio image

Chessie System (No.239-03)
The Chessie System SD-24 enjoys two years
in TYCO's catalogs, 1980 and 1981.

Rio Grande (No.239-74)
There are many differences between the Rio Grande SD24 displayed
in TYCO's catalogs during the '80s and what was actually found in production run examples. The first Rio Grande
example is the catalog picture for the model used from 1982 through 1986. Notice that the model is riding
on the same trucks usually found on TYCO's Super630, E7, and GG1 diesels. Possibly to allow for the different height
of the trucks, the pilots on the above SD24 completely open on the bottom. Both Rio Grande examples are black, but the catalog
example features an orange tint to the stripes and lettering. Also note the stripes on the nose stop at the numberboards
and do not run to the top of the model. Next
is the typical example of the Rio Grande SD24 made by TYCO. The pilot has a lower frame and the
model rides on the more prototypically appearing trucks that are found on many/most TYCO SD24s. The color used for stripes
and lettering is a bright yellow and not the orange found in catalog pictures. The cab number is shown as 5210 in either
example, but the production run model does feature stripes on its nose that continue to the roofline. The regular
production Rio Grande SD24 also features yellow steps, while the catalog example has the orange color applied down
its frame sill and on the pilots, but not the steps themselves.
TYCO Catalog image and Tony Lucio image
R.M.L. -Rocky Mountain Lines (No.239-27)
Found in TYCO's catalogs from the introduction of the SD24
model in 1977 through 1979 is the Comin' Round The Mountain Rocky Mountain Lines SD24. TYCO's catalog images for this
example in many instances were the Atlas model painted in the R.M.L. scheme.
Tony Lucio image
Union Pacific (No.239-23)
The SD24 models shown in catalogs from 1977-1981 are,
for the most part, Atlas models and not TYCO's. Notice the difference between the Union Pacific SD24 shown above, a
real TYCO model, and the Atlas SD24, seen in TYCO catalogs from '77-'81, pictured below. This Atlas model substituting for
a TYCO was done also with the Burlington and Rocky Mountain Line models as well during this period in catalogs.
The Union Pacific SD24 is cataloged by TYCO from 1977 through 1982.
TYCO production model Tony Lucio image
Atlas SD24 is a TYCO Catalog image

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Atlas-Roco's SD-24 vs. TYCO's SD-24
TYCO collector Tony Lucio provides the site with an interesting review
comparison of the 1970s Atlas SD-24 produced by Roco in Europe with the Hong Kong-made TYCO SD-24. From first viewing
both SD-24 models appear similar and it has often been thought that TYCO simply did a knock-off of the Atlas-Roco SD-24.
As we'll see, there are many spotting differences between the two SD-24 shells. Much appreciation goes to Mr. Lucio
for taking the time to compare the shells and provide the images. The models shown are from Mr. Lucio's collection and
consist of a TYCO Chessie System SD-24 and an original Atlas-Roco CB&Q-Burlington Route SD-24 both from the 1970s.
Thanks again to Tony Lucio for his efforts and time!
The Atlas-Roco SD-24 was available for many years under the Atlas name
and later with some modficiation was offered by Con-Cor. Atlas has in recent years produced a series of very excellent
SD-24/SD-26 models with amazing detail and performance characteristics under is Master Series line. The TYCO SD-24 disappeared
with the TYCO train line in the early '90s. IHC-Hobby in 2003 began offering a modified example of the original TYCO
SD-24 molds that remains available to this day.

Differences between the Atlas-Roco and TYCO SD-24 cab and short-hood/nose
are many. The TYCO SD-24 includes what appear to be steam generator stacks and a sand hatch filler on the roof of the
short-hood. These details are absent from the Atlas-Roco SD-24 model. The addition of the sand hatch filler leaves
less room at the tip of the nose roof and TYCO's hood grab iron is smaller than the Atlas-Roco as a result. The Atlas-Roco
SD-24 includes grab irons and ladders up the front of the short-hood/nose, the TYCO model omits these items. Both the
front end headlights and rear headlights share similar differences between the two models. The Atlas-Roco headlights
rest in a more pronounced lens frame or housing, than the TYCO examples. The TYCO headlight lens also appear to
be larger than those on the Atlas-Roco SD-24. The Atlas-Roco model includes a pronounced sunshade above the cab windows,
while the TYCO SD-24 appears to only include the top frame on its cab window. The Atlas-Roco has two distinctly framed
panes for its cab window, the TYCO window appears slightly larger and looks to be two panes located inside one window frame.

The roof detail differs greatly across the two examples. The Atlas-Roco
SD-24 includes a winterization hatch on the first radiator fan, the TYCO fans are all exposed. TYCO utilized what appear
to resemble "button-top" or "Dash-2" flavored radiator fans, the Atlas-Roco model has "dome-style" fans. The TYCO model
includes a grab iron encircling the rear radiator fan, a detail not present on the Atlas-Roco SD-24. The addition of
the radiator fan grab iron causes the piping to lay differently on the TYCO model. The Atlas-Roco's piping has a notch
to its path from the rear end down past the radiator fans, the TYCO SD-24's piping curves out and around these fans.
The Atlas-Roco model includes a oval shaped exhaust stack, while the TYCO's exhaust is a square-cornered rectangluar exhaust
with diamond-pattern grille. The Atlas-Roco exhaust suffers too from a very unsightly injection-molding spure.
Door louvers down the sides of the long hood of the Atlas-Roco SD-24 total five sets on both sides of the model (prototypically
correct); the TYCO includes only a single set near the cab along the engineer's side of the long hood and just two columns
of louvers down the fireman's side of the long hood. The Atlas-Roco model features four hinges on the taller doors on
the long hood, TYCO holds its doors with only three hinges on the taller doors. The Atlas-Roco's radiator grilles feature
more detail than the TYCO example, with the Atlas-Roco including rivets, cross-framing and inset diamond grille pattern.
TYCO's radiators are a simplier design with a flat open grid pattern. The profile of the Atlas-Roco's radiator grille
differs from that of the TYCO SD-24, with the Atlas-Roco's grilles come down lower on the carbody to meet the access
doors on the rear of the long-hood's side. The TYCO radiator grilles don't come down as far and include an open space
between the doors and the grilles. The dynamic brake differs between the two examples, with TYCO's running flush along
its length and the Atlas-Roco model has a notch or step going into the dyanmic's grille. The Atlas-Roco SD-24 includes
a handbrake on the engineer's side, a detail missing from the TYCO shell.

The Atlas-Roco SD-24's plastic handrails feature a bit thinner stanchion than
the TYCO handrails. The truck sideframes on the TYCO model were
originally produced with the general appearance of the EMD design, though TYCO compresses the triple-truck down to fit the
PowerTorque model's truck size. Late examples of the TYCO SD-24 include the completely non-prototypical truck frame
applied to the E-7, GG1, and the majority of the Super630 models. Naturally, the TYCO includes a wide open front and
rear pilot to allow for the swing of the model's truck-mounted coupler. The Atlas-Roco features a nicely detailed set
of pilots and body-mounted couplers. The TYCO SD-24 features a somewhat correct appearing fuel-tank complete with filler
cap. The Atlas-Roco model suffers from the detail-lacking weight fuel tank, this "feature" was probably the biggest
and one of the few strikes against the design of this series of models when first introduced in 1975. The TYCO
model also features open slots cut into the shell to allow for the snap-in of the trucks and fuel tank. The Atlas-Roco
SD-24 had a full frame that snapped onto the shell at the middle of the fuel tank. Finally, the poor TYCO SD-24 is powered
by the PowerTorque truck and never was much of a performer, while there doubtless many Atlas-Roco SD-24s still proudly serving
their owners to this day.
Below is a portion of the advertisement that announced the first of the Atlas HO-Scale diesel locomotives
in early 1975. The SD-24, produced for Atlas by Roco, was quickly followed by the SD-35; high-nose and later lose-nose
GP-38; GP-40; and FP-7 models. To see the 1970's Atlas-Roco diesel offerings, click on the image of the Atlas SD-24
below...

IHC revisits TYCO's SD-24...
IHC (International Hobby Corp.) released a new group of SD-24 models in
HO-scale in the fall of 2003. This IHC offering is an updated version of the former TYCO model. As many TYCO collectors
know, IHC acquired certain items from the defunct TYCO line in the 1990s and has issued various former TYCO models under the
IHC name in recent years.
These IHC SD-24s feature a drive will all 12 wheels powered and is listed among IHC's
"Premier Series" of locomotives. IHC has removed the many open slots along the frame of the unit that TYCO used to hold the
trucks and fuel tank onto the shell. The new IHC SD-24s feature a complete underframe and re-designed fuel tank that fits
nicely under the shell.
IHC's SD-24 first appeared in 2003 in SHOP-RITE promotional train sets and next served as
the power for a "James Strates" circus train set.
IHC has offered
a number of interesting roadnames and paint schemes for this model. Among them are a few that harken back to the fantasy schemes
of the famed TYCO era. The "Presidential" SD-24, pictured below, is prime example of what might be considered modern TYCO...
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