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Atlas O Trainman RSD4/5

Review and Photos by George Brown
June/July ’06 Issue of O Gauge Railroading

            The RSD4/5 is the first diesel locomotive in the new, lower-priced Trainman line from Atlas O. Sized at a full 1:48 scale, the RSD runs on either 3-rail with O31 minimum curves or on 2-rail. To reduce price and also make for a stronger overall product, many details are cast or molded into their respective component rather than being the separate but occasionally fragile details that distinguish Atlas O Master Line diesels. Details cast into metal components do not seem to have the depth of relief that I enjoy seeing on current-production Master Line diesels; but even with most details molded or cast-in, the Trainman RSD is definitely not a stripped-down, plain-Jane locomotive.

            With the stage now set, let's take a close look at the Trainman RSD4/5.


            Mechanically the Trainman RSD follows the conventional architecture used by several manufacturers for contemporary O gauge diesels, with some notable exceptions. A plastic shell assembly rides on a stamped steel frame rather than on the die-cast frame of Atlas Master Line diesels. This shell includes a separately molded cab that straddles a one-piece hood with molded walkways. Cab windows are clear plastic, and walkway handrails are wire with pressed metal stanchions. Molded-in details on this assembly consist of door handles and hinges, vents, radiator grills, rivets, and nonslip walkway pattern. These details are crisp and visible, even with the Cotton Belt “Black Widow” livery on our evaluation RSD.

            On top of the long hood, a see-through etched-metal fan grill covers the realistic three-bladed fan. Separate wire grab irons adorn both hoods, with a single horn mounted in front of the cab — yes, the Trainman RSD is wired to run long hood forward. After removal of the four screws holding it in place, the shell assembly comes off the frame with no fuss or muss, and it goes back on just as easily. Without a doubt, the RSD is the easiest Atlas O engine I've disassembled, ever!

            Under the frame, the two-piece die-cast speaker housing adds necessary weight for traction and also represents the RSD's fuel tank, battery box, and air reservoir. A can motor with a flywheel mounts on each of the die-cast trucks and drives all three wheelsets via the same all-metal gear train that drives Master Line diesels. Die-cast side frames follow the RSD prototype with drop-center equalizers, friction bearing journal boxes, and brake cylinders with air lines. Flanged wheels are at each end of the trucks with a blind wheelset at the center. Between low gearing and four traction tries on each truck, the Trainman RSD is a heavy hauler, especially considering the engine's average weight (see the RSD's performance numbers).

            On each 3-rail pilot, Atlas O's unique but cosmetic draft gear box encases the company's own coil-actuated tinplate coupler with a removable plastic air hose/isolation valve mounted on one side. This hose has to come off for adequate coupler swing on O31 curves, but it's an easy off-and-back-on, too. Multiple unit lines are cast into the pilots on both 3-rail and 2-rail versions. Of course, 2-rail RSDs have scale automatic couplers.

            Last, but certainly not least, is the flawless Atlas O finish and precise decoration and lettering, but with one surprise. The black truck side frames have a pristine gloss finish, unlike the satin paint on the rest of the engine. As Jim Weaver of Atlas O explained, this gloss black is a chemical coating and not paint, but since it is only available in black, colored trucks are painted.

            Those of us who have to employ something like a Mini Maglite to see nearly invisible stamped or raised ID labels for the electronics control switches, which are usually located under the engine frame and are also frequently obscured by a truck, labels on the RSD are large, easy-to-read white letters — very thoughtful!

            The only digression I could find from the Black Widow scheme of full-scale Cotton Belt RSDs is the model's black handrails rather than the prototype's yellow, which is a trivial compromise to Trainman's lower cost. As a side note, only the SP-owned Cotton Belt had yellow handrails on their Black Widow road switchers. Handrails were predominantly black with silver trim on Black Widow road switchers owned by the SP and the SP-owned Texas and New Orleans.


            Trainman 3-rail engines are available with either a conventional electronic reverse unit licensed from Williams with horn and bell sounds or Lionel's TrainMaster Command Control (TMCC) with RailSounds version 4.0. TMCC-equipped RSDs use a Lionel motherboard and DC motor driver (DCDR) as well as the three Lionel circuit boards used in every TMCC locomotive: the R2LC command receiver plus the RailSounds power supply and amplifier. Installing an owner-supplied 9-volt alkaline battery for RailSounds backup requires taking the shell off the frame, but that’s easy, as I mentioned earlier.

            Both TMCC and conventional-only versions of the RSD have constant brightness, directional lighting that uses golden white LEDs, which I like, rather than brilliant blue-white lights, which I don't. Lighted number boards get their illumination from the LEDs reflecting inside the shell.

            Because of the cost premium for speed control, it is not available in Trainman engines. But as I'll get into in a few lines, I didn't miss speed control with our evaluation RSD. A smoke generator also fell to cost reduction, but for O gauge railroaders, including me, who shut off their smoke units anyway, I didn't miss that either.


            Out of box, the RSD ran well, and after a couple of hours of break-in plus setting its TMCC stall voltage, it was a superb runner. At scale speeds of over 10 scale miles per hour with track power of 14 to 18 volts, the RSD maintained whatever speed I set with only minor slowdown as it ran through O42 or tighter curves. Even switching cars worked well with good response to changes at the CAB-1 throttle. Although I enjoy running engines at a self-regulating crawl or other speed, I have to question if maybe the complexity, cost, and sometimes quirky behavior of speed control electronics are necessary, especially with the smooth-running Trainman RSD4/5 on a flat layout like mine.

            Our RSD negotiated O31 curves and Lionel O22 turnouts with the agility of a much smaller engine, even with its scale-length and long-wheelbase three-axle trucks. The only glitch was the engine's center-rail pick-up rollers, which happen to be spaced the same as the distance between the insulated frogs on my two point-to-point O22s. The RSD's large flywheels carried it across the insulators with no more than a headlight blink resulting from the momentary dead spot. Since I had installed the RailSounds backup battery for running the RSD in transformer-controlled conventional operation, RailSounds stayed up during the momentary power interruptions.

            A broken wire from the center-rail pick-up roller sent the RSD into the CCRR's backshop, where a few minutes with soldering tools took care of the situation. The wire broke off its terminal after the engine ran only a few passes through my O31 reverse loops, although it had already run well for over an hour on my wide-curve main line. So to relieve any strain on the other pick-up wires when the trucks pivot to their left or right limits, I also repositioned those wires on their respective mounting screws. Jim Weaver sent a second RSD, finished in a handsome and flawless Santa Fe blue and yellow, that ran without any problems on my O31 curves and reverse loops.

            RailSounds in the RSD reproduces the distinctive throb of the ALCO 244 prime mover, with a single-tone horn for accompaniment. These sounds are the same repertoire that ran in the Atlas RS1, reviewed in Run 200 (OGR April 2004).

At the End of the Day

            With its inaugural Trainman RSD4/5, Atlas has succeeded admirably in its response to customer and dealer requests for products with lower cost, robust details, and scale size trains that run well on traditional O31 layouts. Suggested retail prices are attractive, and the discounted prices available from some dealers make the Trainman RSD even more attention grabbing. At these prices, anyone for double-heading a pair of RSDs?



Prototype Notes: Cotton Belt RSD5

            ALCO's postwar 1600 hp RSD4 or RSD5 six-axle road switchers were nearly the same engines as the four-axle RS3 and six-axle RSC3. Uneven spacing of the RSD's double-equalized trimount truck visually identified it as ALCO's three-motor "C" truck for heavy duty service, such as climbing mountainous grades. Evenly spaced axles of the RSC3 indicated the two-motor A-1-A truck, intended for normal service on light roadbed.

            Atlas O Trainman RSD4/5 models prototype ALCOs equipped with C trucks and an air-cooled turbocharger, as indicated by the exhaust stack placed lengthwise on the long hood. The stack for engines using the later and less problem-prone water-cooled turbocharger sat crosswise on the hood. Our evaluation RSD represented one of three RSD5s that served the Southern Pacific-owned St. Louis Southwestern Railroad, the Cotton Belt Route, from 1953 to 1969.


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