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WalthersProto HO scale EMD SD9 diesel

Read this review from the February 2020 Model Railroader
WalthersProto HO EMD SD9 diesel
WalthersProto HO scale EMD SD9
An HO scale General Motors Electro-Motive Division SD9 diesel is back on HO scale rails thanks to Wm. K. Walthers Inc. Part of the WalthersProto series, the model is accurately detailed and decorated for several road names. We reviewed an earlier release of the model in the December 2012 issue. This upgraded release is available with a factory-installed dual-mode ESU LokSound Select (V.4.17) decoder that provides realistic sound on Digital Command Control (DCC) and direct-current (DC) layouts.
WalthersProto HO scale EMD SD9 diesel
WalthersProto HO scale EMD SD9

The prototype. General Motors’ Electro-Motive Division (EMD) produced 471 SD9 locomotives for North American railroads. The SD9 featured a 16-cylinder 567C diesel engine and six-axle Flexicoil trucks. Rated at 1,750 hp, the SD9 was a more powerful version of its 1,500 hp predecessor, the SD7.

The locomotive’s C-C configuration meant three traction motors on each truck. This gave the SD9 75,000 pounds of continuous tractive effort.

The Milwaukee Road purchased 14 SD9s (numbered 2224 to 2237) in early 1954. They were renumbered 530 to 543 in 1959, and once more, using nonconsecutive 500-series numbers, in 1975. Serving for nearly three decades, the locomotives hauled freight throughout the Milwaukee Road system, including out west in Washington State.

Although most Class 1 railroads stopped using SD9s by the 1980s, some still labor on today.

The model. The HO diesel’s major dimensions closely match prototype drawings in the 1956 Locomotive Cyclopedia of American Practice (Simmons-Boardman Publishing Corp.). Well-defined molded detail, including louvers and engine-access doors, match the prototype.

Decorated and detailed for Milwaukee Road no. 530, our review sample represents its prototype as it appeared in the 1960s and early 1970s. Prototype-specific details include all-weather cab windows, dual sealed-beam headlights, spark arrestors over the exhaust stacks, and winterization hatch.

The plastic end ladders and wire grab irons are separately applied. The handrails are flexible plastic with the correct bolted stanchion details.

The paint is smoothly applied with sharp separation between the black and orange stripes. The placement of the road numbers, heralds, and builder’s plates match prototype photos.

WalthersProto HO EMD SD9 diesel
Walthers HO scale EMD SD9
The mechanism. After removing the couplers and two screws just behind the fuel tank on the underframe, I carefully lifted off the plastic body shell. The motor and brass flywheel are mounted in the center of the die-cast metal chassis. There are additional die-cast metal weights at each end. Universal shafts run from the motor to truck-mounted gearboxes, powering all six axles.

The main printed-circuit (PC) board is attached to the rear weight. On our DCC-equipped sample, the decoder is plugged into a 21-pin socket on the main PC board. There are light boards at each end with separate surface-mount light-emitting diodes (LEDs) to illuminate the headlights and number boxes. The well-enclosed vertically mounted speaker is located just in front of the motor.

Pulling power. The model’s all-wheel drive mechanism and nearly 1 pound weight helped it achieve a drawbar pull equivalent to 47 free-rolling HO scale freight cars on straight and level track. During a hill climb test, the SD9 pulled an 11 car train up a 3 percent grade without slipping or stalling.

The gearboxes also feature 14:1 helical gears that have teeth cut on an angle rather than straight across. This provides exceptionally smooth performance, espe-cially at low speed. Even at a crawl there was no discernible jerking or stalling.

I also appreciated that the Proto-Max couplers are metal and sturdy enough to handle repeated switching duty during an operating session. The couplers reliably couple and uncouple to other Kadee-compatible couplers.
WalthersProto EMD SD9 performance charts

DCC operation. As shown in the performance charts above, the model started moving steadily at less than 1 scale mph in speed step 1 and accelerated to a top speed of 68 scale mph, close to one of the gearings available on the prototype.

The decoder accurately captures the prototype’s sounds, including the rumble of the EMD 567C diesel engine and the distinctive bleat of the dual single-chime air horns.

Other user-triggered sound effects include the bell, coupler, compressor, and a realistic engine start-up sequence. Pressing function 9 triggered Drive/Hold, which kept the locomotive speed steady so I could use the throttle knob to manually notch the engine rpm up or down. Function 10 applies or releases the independent brake.

Virtually every aspect of the ESU LokSound decoder can be adjusted using configuration variables (CVs). An ESU LokProgrammer (sold separately) makes this task much easier. For example, I remapped the headlights for prototypical non-directional control. It’s also easy to adjust volume levels, momentum, and other features. Even if you don’t purchase the computer interface, the free LokProgrammer software is an invaluable programming aid for LokSound decoders. You can download it, as well as a user manual, at

DC operation. The model also performed smoothly on our DC test track. Sounds and lights started at 6.5V. The SD9 began creeping along at 2 scale mph when I advanced the throttle to 8V and accelerated smoothly to 55 scale mph at 12V.

The ESU decoder provides some realistic momentum in DC mode, making for realistic stops and starts. I especially enjoyed how the engine rpm increases before the locomotive starts moving, just like the prototype.

In DC mode, sound and light effects are limited to the directional headlight, engine rpm, and the compressor and other random sounds. As on the prototype, the number boxes are illuminated on both ends regardless of the locomotive’s direction. Squealing brakes sounded when I quickly reduced
the throttle.

Prototypical sounds and detailing make the WalthersProto SD9 a standout model of this first-generation diesel workhorse.
Facts & features
Price: $299.98 (DCC sound), $199.98 (DC, no sound)
Wm. K. Walthers Inc.
5601 W. Florist Ave.
Milwaukee, WI 53218
Era: 1954 to 1980s (as detailed)
Road names (multiple road numbers): Milwaukee Road; Chicago, Burlington & Quincy; Elgin, Joliet & Eastern; Nickel Plate Road; Southern Pacific (“black widow” and gray/scarlet schemes)
  • All-wheel drive and electrical pickup
  • Die-cast metal frame
  • ESU LokSound Select dual-mode decoder
  • Five-pole, skew-wound motor with brass flywheel
  • Light-emitting diode headlights
  • Proto-Max metal knuckle couplers at correct height
  • Weight: 15.3 ounces

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