Atlas, N scale, EMD SD24 locomotive

This sweet-running, finely detailed ready-to-run N scale model of Electro-Motive Division’s SD24 is made by Atlas Model Railroad Co. It’s offered in both low and high-nose version with optional Digital Command Control (DCC) decoders.

The SD24 (Special Duty 2400 hp) was a milestone in EMD’s history–the first time the company cataloged a turbocharged version of its 16-cylinder 567 engine. Turbochargers force more air into the cylinders to produce more power than normally aspirated versions of the same diesel engine.

Today, the smooth whine of turbocharged EMD locomotives is as much a part of the railroad environment as ties and turnouts, but in the 1950s turbocharging was a hotly debated subject at EMD. However, Union Pacific’s 1955 experiments with turbocharging forced the issue. The company announced its first turbocharger-equipped models in 1958, including the six-axle C-C SD24, in a colorful brochure that thundered, “Not since the introduction of the General Motors wide-range F3 locomotive in 1945, has Electro-Motive made an announcement of such significant economic importance to American railroads.”

A total of 224 SD24s were built, including 45 cabless (B-unit) SD24s for Union Pacific.

Among the SD24’s noteworthy features were its four roof-mounted air reservoirs. The locomotive’s 3,000-gallon fuel tank took up so much of the underframe that the reservoirs had to be mounted upstairs. A bulge in the left side of the long hood behind the cab marks the turbocharger’s location.

The Atlas N scale SD24 closely matches the dimensions listed on EMD’s specification sheets. The blue-and-yellow paint on our Santa Fe locomotive was crisply applied. All the key SD24 features are present, from the “chicken wire” radiator grills that protrude slightly from the sides of the locomotive, to the tall access doors behind the cab.

The air brake piping along the roof is exceptional and very delicate. Being a bit clumsy, I managed to pop it loose the first time I handled this locomotive. A very tiny drop of fast-curing cyanoacrylate adhesive (CA) at the end of a needle put things right.

The model features a split metal frame that includes a recess at the rear to accommodate a Digital Command Control (DCC) decoder. The directional headlights are golden-white light-emitting-diodes (LEDs), a great improvement over the bluish-white LEDs used on some previous Atlas models.

Accumate magnetic knuckle couplers are body-mounted on both ends at the proper height.

The SD24 performed well on the test track, creeping along smoothly at about 6 mph. Road-switcher hoods don’t leave much room for weight, but the locomotive managed .64 ounce of drawbar pull and wheeled a 15-car test train through no. 4 turnouts without a hitch.

This is a great-running, great-looking model of a standout prototype locomotive.

N scale EMD SD24

Price: $99.95 each; $134.95
with DCC decoder

Manufacturer:
Atlas Model Railroad Co.
378 Florence Ave.
Hillside, NJ 07205
www.atlasrr.com

Description:
Plastic-and-metal ready-to-run
locomotive

Features:
Body-mounted Accumate
magnetic knuckle couplers
Directional lighting with golden
white light-emitting diodes
Five-pole skewed armature
motor with dual
flywheels
Minimum radius: 9.75″
Railroad-specific details
Scale 40″ chemically blackened
RP-25 contour nickel-silver
wheels (in gauge)
12-wheel drive and electrical
pick-up
Weight: 3 ounces

Road Names:
(two numbers each)
Low hoods: Atchison, Topeka
& Santa Fe; Union Pacific;
and undecorated (two
versions)
High hoods: Chicago,
Burlington & Quincy; Southern
Ry.; and undecorated (two
versions)