InterMountain Railway Co., N scale, SD40T-2

A handsome N scale SD40T-2 tunnel motor locomotive is now available from InterMountain. It features a detailed plastic body, six-wheel trucks, and a smooth-running dual-flywheel mechanism that can be easily adapted for Digital Command Control (DCC).

This well-proportioned model is a replica of the 3,000-hp prototype that was introduced in 1974. It’s essentially a modified SD40-2 that Electro-Motive Division built for the Southern Pacific with lower radiator intakes for better performance in high-altitude tunnels. Given their purpose, the new units were nicknamed “tunnel motors.”

These units resolved SP’s high-altitude problems and impressed the Denver & Rio Grande Western as well. Eventually, the Rio Grande purchased 73 tunnel motors, while SPs fleet grew to 239 units.

InterMountain’s tunnel motors are offered in several versions that match the variations in the prototype orders. The carbodies have a standard long hood that’s combined with five different noses, two cabs, two fuel tanks, and two bells. Other details such as air conditioners, radio antennas, and snowplows are applied as required.

The model tunnel motor closely matches prototype photos and dimensions in railroad equipment diagrams. More information can be found in Greg McDonnell’s Field Guide to Modern Diesel Locomotives, (Kalmbach Books).

Our samples came assembled and ready-to-run with Micro-Trains magnetic knuckle couplers. (An earlier group of four road names had Accu-Mates). Clear plastic window glazing is fitted into the cab with appropriate window wipers.

All three of our samples were smoothly painted with sharply printed lettering. Even the tiny red and white DANGER 600-VOLTS warning labels were readable under magnification.

The SD40T-2’s mechanism follows the popular split-frame design used in most N scale diesel models. Its frame halves are zinc alloy castings which enclose the five-pole skew-wound motor and truck pivots. Two turned brass flywheels are mounted on the motor shafts which drive gearboxes riding on top of the six-wheel trucks.

The scale 42″-diameter nickel-silver drivers and wheelsets match the National Model Railroad Association N scale standards gauge.

A printed circuit board mounted on top of the chassis holds the model’s LED headlights and control circuitry. It can be easily replaced with drop-in decoders for Digital Command Control (DCC) which are available from Digitrax (no. DN1631O) and North Coast Engineering (no. N12AO-E).

Performance. Our sample EMD SD40T-2s performed well. Though they seemed a little stiff at first, the drive mechanism ran smoothly after running for a short period of time. All three started at virtually the same speed and voltage, and I could get them to run steadily at 4.8 scale m.p.h. The engines’ drawbar pull is equivalent to 19 free-rolling freight cars on straight and level track.

InterMountain’s tunnel motors operated well on a 9″ minimum-radius curve; of course, they’ll look much better running on an 11″ or larger radius curve.

The Micro-Trains knuckle couplers are mounted at the correct height in boxes attached with small Phillips screws.

I’m happy to see these excellent SD40T-2s with railroad-specific details appearing in N scale. Their different profiles will certainly add realism to any train heading into the picturesque Front Range of the Rockies or California’s rugged Sierra Nevada Mountains.

N scale SD40T-2 locomotive

Price: $119.95 each

Manufacturer:
InterMountain Railway Co.
P.O. Box 839
Longmont, CO 80502-0839
www.intermountain-railway.com

Description:
Plastic and metal locomotive

Road names:
Denver & Rio Grande Western; Cotton Belt; New York, Susquehanna & Western; Southern Pacific (five schemes); Union Pacific (two schemes); and undecorated

Features:
Brass bell and horn
Drawbar pull: .8 ounce
Engine weight: 3.25 ounces
Five-pole skew-wound motor
with dual flywheel drive
Micro-Trains magnetic knuckle
couplers
LED constant directional
headlights and ditch lights
Minimum radius: 9″
Railroad-specific details
Six-axle drive and electrical
pickup