A General Motors Diesel Ltd. SD50F is the second HO scale road locomotive released by Aurora Miniatures North America Inc. The six-axle unit, based on a prototype built for Canadian National, features an injection-molded plastic body; a heavy, die-cast zinc alloy chassis; and an assortment of light-emitting-diode lighting features.
Prototype history
Canadian National ordered two groups of SD50F diesels. The initial 40 units, constructed between April 1985 and February 1986, were built under order number C-455. The road locomotives were numbered 5400 through 5439 and assigned to the railroad’s GF-636a class.
An additional 20 units were produced between February and July 1987 under order numbers C-461. The diesels, 5440 through 5459, were assigned to the GF-636b class.
Four units, designated SD50AF, were built between August and October 1985. The class GF-638a units were originally numbered 9900 through 9903 but renumbered 5500 through 5503.
Our sample is decorated as Dakota, Missouri Valley & Western 5454. The SD50F was built in March 1987 for CN with the same number. It was sold to the regional carrier, based in Bismarck, N.D., in 2008.
Model features
The Aurora Miniatures model features many separate, factory-applied parts, including a snow plow, m.u. and train line hoses, and formed wire uncoupling levers. The 5454, part of the GF-636b class, accurately has the horn adjacent to the exhaust stack on the carbody and the ditch lights mounted on the deck.
The front and rear handrails and stanchions are painted plastic parts. Formed wire was used for the vertical handrails and grab irons. The steps are see-through, etched-metal parts.
The SD50F has a four-piece windshield with flush-fitting glazing and freestanding wipers. Among the items in the detailed cab interior are three seats, an upper and lower console, and an electrical cabinet.
The road unit has a full-width carbody with the signature Draper taper behind the cab for improved visibility to the rear from inside the cab. The feature was named after CN’s Assistant Chief of Motive Power William L. Draper. The air filter box for the electric compartment is located behind the cab on the conductor’s side. Rooftop details include a winterization hatch, etched-metal radiator intake screens, and metal lift rings.
Sometime in the 2010s, the cab access steps, vertical handrails, and door handles were removed from the engineer’s side on the 5454 and other SD50Fs in the DMVW fleet. The red-and-white stencil below the door indicates the door is no longer usable. The handrails and steps are included as modeler-installed parts, which I added.
Operating radiator fans are certainly the star of the show on this model. The improved fan drive unit is much quieter than on Aurora’s HO scale SD60F.
On the test track
Our review sample is neatly painted in DMVW’s orange-and-gray paint scheme. The orange is opaque, and the color separation lines are crisp. The lettering placement matches prototype images that I found online.
The model we received is equipped with an ESU LokSound V5 sound decoder. The SD50F does not include a printed instruction manual. It’s available under the Product Support tab on the manufacturer’s website.
The manufacturer doesn’t recommend running DCC models using direct current. For workbench testing, I used an NCE Power Cab. At step 1, the road locomotive moved at less than 1 scale mph. At step 28, the model achieved a top speed of 51 smph.
For real-world testing, I took the SD50F to the Winston-Salem Southbound. The six-axle unit had no issue navigating the No. 4 turnout and 30-degree crossing while switching industries on the Tar Branch.
I’ve always been a fan of cowl-bodied diesels, and Aurora Miniatures has done a fine job on its HO scale SD50F. The freestanding detail parts, combined with lights, sounds, and animation, make this six-axle road unit a real eye-catcher.
Facts & features
Price: Direct-current model with 21-pin MTC connector and dual sugar cube speakers, $249.99; with ESU LokSound V5 sound decoder, $349.99
Manufacturer
Aurora Miniatures North America Inc.
20 Kilchurn Castle Dr.
Toronto, Ontario, Canada
M1T 2W4
na.auroraminiatures.com
Era: April 1985 to present (varies by road name)
Road names: SD50F — Dakota, Missouri Valley & Western (gray and orange with reporting marks on body) and Canadian National (North America, single stripe, and zebra stripes). SD50AF — CN (zebra stripes) and DMVW (herald on body). One to four road numbers per paint scheme.
Features
• Body-mounted AuroraJanney couplers, at correct height
• Metal wheel stubs mounted on plastic axles, two out of gauge
• Minimum radius, 18”; recommended radius, 22”
• Weight: 1 pound, 5.7 ounces
