The Electro-Motive Division SD75M diesel locomotive has joined the WalthersMainline HO scale product range. The newly tooled model features an injection-molded plastic body; heavy, die-cast metal chassis; and all-wheel drive and electrical pickup.
Prototype history
Electro-Motive Division produced the SD75M from February 1995 through February 1996. A total of 76 units rolled off the production line during that time. The six-axle road locomotive is equipped with a 16-710G3 diesel engine, an AR20 alternator, and D90TR traction motors. The 4,300 horsepower locomotive rides HTCR-1a trucks and has a 5,000-gallon fuel tank.
Atchison, Topeka & Santa Fe ordered 51 units, numbered 200 through 250. These were the last units ordered by Santa Fe prior to its merger with Burlington Northern in 1995. They were delivered in Santa Fe’s red-and-silver Superfleet (warbonnet) scheme.
After the merger, Burlington Northern Santa Fe took delivery of 25 EMD SD75M diesels. The locomotives, numbered 8251 through 8275, also wore the red-and-silver scheme, but had BNSF on the long hood instead of Santa Fe.
The sample we received is decorated as BNSF 8252. The full-size unit was built in December 1995 under order number 956608. It was repainted in Heritage II colors on May 6, 2002. In 2014 the road locomotive was renumbered 252, as the 8200 series was reassigned to an incoming order of General Electric ES44C4 diesel locomotives. The 252 was overhauled and repainted in Heritage IV colors in 2017. The unit is still in service today.
Model features
The plastic body on the SD75M consists of the long hood, cab, nose, and sill unit. The front pilot has a factory-applied snow plow, and the rear pilot has molded spare knuckles. Both pilots have molded m.u. hose connections and m.u. sockets.
Drill-starter points are located on the nose, cab, and long hood. Walthers offers an EMD SD70-series diesel detail kit that includes formed stainless steel wire grab irons as item No. 910-261 ($19.98, sold separately).
The front anticlimber has a pair of ditch lights. All of the walkways feature raised treadplate detail. The handrails and stanchions are molded in flexible engineering plastic. The vertical railings in the step wells are painted white, as are the step edges.
The trim on cab windows is picked in black and aluminum as appropriate. A detailed cab interior is visible through the clear, flush-fitting window glazing.
Long-hood details, such as the dynamic brake fan, radiator cooling fans, inertial filter inlets, cooling air inlets, and engine access doors are molded. The plastic SD75 body bulge and brake wheel on the engineer’s side, as well as the cast brass Nathan K5 air horn on top of the long hood, are factory-applied parts.
The BNSF Ry. model has plastic HTCR-1a trucks with raised foundry data and freestanding brake cylinders and shock struts. Additional details below the sills include the left and right air reservoirs, a bell behind the front truck on the conductor’s side, and a 5,000-gallon fuel tank. The sight gauges, filler caps, and emergency shut-offs are painted red on our sample.
To separate the shell from the chassis, I removed the front and rear draft-gear boxes plus two additional screws (one on each end of the fuel tank). A five-pole, skew-wound motor framed by machined brass flywheels is centered in the chassis.
Much of the space around the motor is filled by the top weight. A 21-pin motherboard is secured to the top of the weight with screws. The ESU decoder sits atop the motherboard. A 28mm round speaker is housed in an enclosure above the rear truck.
The model includes Proto-Max metal couplers and factory-installed brass air horn.
Our review model is neatly painted in BNSF Heritage II paint scheme. The color separation lines are crisp, and the yellow stripes and lettering are opaque with minimal gapping around the hinges and other details. The lettering placement follows prototype images, though the sill stripe arrangement is a bit different. The intermediate-level model lacks details such as cab sunshades, antennas, windshield wipers, wind deflectors, mirrors, and various warning and safety labels.
There were a few minor discrepancies between the model and prototype. The nose headlight housing and walkway guard on the engineer’s side should be orange, and the ditch light housings should be yellow. The full-size 8252 has a K3 air horn with reverse bell No. 4. The brake wheel is also different from that found on the prototype 8252.
Prototype drawings of the EMD SD75M appeared in the November 1995 Model Railroader (with corrections in the March 1996 issue), as well as BNSF Railway Company 2006 Locomotive Review and Locomotive Diagrams by Robert C. Del Grosso (Great Northern Pacific Publications, 2006). The dimensions on the Walthers HO EMD SD75M closely follow published data.
To the test track
I tested the model at the workbench with an NCE Power Cab. At step 1, the six-axle locomotive moved smoothly at 1 scale mph. At step 28, the locomotive achieved a top speed of 70 smph, an exact match for the prototype. The SD75M has a drawbar pull of 6.4 ounces, equivalent to nearly 90 free-rolling freight cars on straight and level track.
In addition to the SD75M, Walthers offers the SD70M and SD75I in its Mainline series. The HO scale models look good right out of the box, but can also serve as the starting point for a fun detailing and weathering project.
Facts & features
Price: Direct-current model with 21-pin DCC plug and factory-installed speaker, $169.98; with dual-mode ESU sound decoder, $229.98
Manufacturer
Wm. K. Walthers Inc.
5601 W. Florist Ave.
Milwaukee, WI 53218
Era: 1995 to present (varies based on paint scheme)
Road names: BNSF Ry. and Atchison, Topeka & Santa Fe. Four road numbers per scheme. Also available undecorated.
Features
- Body-mounted Proto-Max couplers, at correct height
- Metal wheel stubs mounted on plastic drive axle gears, correctly gauged
- Minimum radius, 18”; recommended radius, 22” or larger
- Weight: 1 pound, 6.5 ounces
