Athearn HO MP15AC diesel switcher

The eagerly anticipated Athearn Genesis HO Electro-Motive Division MP15AC switcher is here, and its performance is worth the wait. This great-looking model is offered in a DC version without sound or with a dual-mode Digital Command Control (DCC) decoder that produces sound effects in either mode. These models have excellent railroad-specific details and include a powerful, smooth-running mechanism. Locomotives with the sound system come with a handheld radio control to operate sounds on DC layouts.

The prototype “MP” designation refers to the multi-purpose design of these locomotives, which were introduced in 1974. The 1,500-hp units have EMD’s standard switcher profile, but carry more fuel and ride on the same GP trucks used on road locomotives so they can operate at road speeds.

The MP15AC was the first switcher fitted with EMD’s Dash 2 modular, solid-state AC electrical system. These units are easy to distinguish, thanks to the plain front on the hood and their tunnel-motor-style radiators with see-though side air intakes. The MP15AC also has an additional 6″ of space between the trucks so it can be fitted with a 1,600-gallon fuel tank.

Between 1975 and 1984, 255 units were built, with the largest fleets going to the Milwaukee Road (64), Southern Pacific (58), Seaboard Coast Line (45), and Long Island (23). Most of these MP15ACs remain in service, with many repainted into the post-merger color schemes of today’s Union Pacific (93), CSX (55), and CP (27).

Athearn’s model matches the prototype dimensions shown in MP15AC drawings published in the Simmons-Boardman 1980 Car and Locomotive Cyclopedia.

The mechanism. This new Genesis diesel switcher follows Athearn’s proven mechanical design. It has a Roco five-pole motor that’s dynamically balanced and fitted with turned-brass flywheels to produce smooth slow-speed performance.

The motor is mounted in the middle of a die-cast metal chassis that provides most of the weight for traction. Acetal plastic shafts and universals drive all of the axles with minimal noise.

The EMD GP trucks have excellent sideframes detailed with the correct roller bearing end caps, brake hangers and shoes, swing hangers, and factory-applied air brake cylinders. Each truck is driven by a worm and set of spur gears enclosed in a snap-together gearbox. The RP-25-contour drivers are mounted on stub axles pressed into tubular gears. The wheelsets are blackened nickel-silver and they match National Model Railroad Association standards. The split axles allow all eight wheels to pick up current through contacts wired to the unit’s printed-circuit board.

Body details. Athearn adds an assortment of alternate parts to the body shell to provide prototype- specific details for each road name. A variety of hand-applied plastic, etched metal, and wire parts further customize each model. Both pilots include scale-size molded acetal plastic m.u. and air hoses and uncoupling levers.

The numerous windows in the standard cab show off the locomotive cab’s interior, which is the best I’ve seen in any commercial HO scale model. It includes a control stand, numerous access doors (with printed safety stickers), and a pair of properly shaped seats.

Plastic pins slip into the ends of the chassis to align the carbody
on the mechanism. The coupler boxes slip through the pilots and are attached with single screws at each end to secure the body shell.

Both of our samples were smoothly painted with sharply defined color breaks. The printed lettering is crisp and opaque, including the EMD builder’s plates

Dual-mode electronic system. The MP15AC’s electronics offer a wide range of sound choices that can be programmed in either DC or DCC modes. A single 8½” x 14″ instruction folder explains the choices and how the user can program the system.

A small (15/8″ x 3¼” x ½”) battery-powered, handheld radio transmitter has numbered push buttons to control the sound functions during DC operation: 1, turn bell on or off; 2, sound the horn; 3, activate a coupling crash; 4, activate a stand-ing air release (or an emergency red light on Southern Pacific models); 5, activate an air release; 6, switch the headlight on or off.

These buttons also program the sounds, and some functions include audio confirmations. The program offers 15 different horns, 6 bells,
a variety of bell-ringing rates, and a sound system on or off.

In DCC, these models use 29 functions (F0-F28) to control a wide range of features. The sound system can be toggled on and off with F12. There are also 37 configuration variables (CVs) that adjust the sound and DCC settings. In case of an error, the decoder can be reset to its factory settings.

Performance. The model’s electronics require 6 volts to start the sounds in DC mode, so all speed control occurs in the top half of the throttle range. Our MP15AC sample started moving smoothly on 7.0 volts DC at a scale 3.8 mph. It reached a scale 74.2 mph, which is only slightly higher than the prototype’s 70 mph maximum. The model’s 2.9 ounce drawbar pull is equivalent to 40 free-rolling HO scale freight cars on straight and level track.

Our tests were run at the factory default settings, but some programming adjustments can be made to further reduce the starting speed.

On DCC the engine sounds start at idle and rev up on throttle step 1 as the unit begins to creep. At full throttle (step 28), the locomotive reaches 90 mph, but its CVs can be adjusted for a more realistic top speed. The model also supports 128 speed steps for finer control.

Though it’s relatively compact, this MP15AC is an impressive model. It combines classic good looks, excellent detail, and a powerful mechanism with sound effects that can be used on DC or DCC layouts.

HO MP15AC diesel switcher
Price: MP15AC with dual-mode decoders and sound, $229.98 each; DC versions $129.98

Manufacturer
Athearn Inc.
1550 Glenn Curtis St.
Carson, CA 90746
www.athearn.com

Description: Plastic and metal ready-to-run diesel locomotive with sound and DCC

Road names: (available with or
without DCC & sound):
Canadian Pacific (beaver),
CSX, Milwaukee Road, Soo
Line, Southern Pacific, Union
Pacific (Ex-Milwaukee Road),
UP (Ex-Missouri-Kansas-
Texas), and undecorated

HO EMD MP15AC features
Automatic dual-mode sound decoder for DC or Digital Command Control (DCC)
(in DCC and sound equipped versions)
Cab interior, flush window glazing
DC models include an NMRA-recommended 9-pin DCC decoder socket
Die-cast metal chassis
Directional, constant lighting
Drawbar pull: 2.9 ounces
Factory-applied, prototype-specific details
Five-pole balanced Roco can motor with dual flywheels
McHenry scale-size magnetic knuckle couplers mounted at the correct height
Minimum radius: 18″
See-through fan intake openings
Weight: 10 ounces