Introduced: 1992 (Kato-made version), 1997 (Atlas Classic version), 2006 (DCC version), 2008 (GP30 Phase 1) and 2020 (DCC-Sound versions)
Atlas's first GP30 model actually came out in the 1970s and was manufactured by Roco (Austria). However, I won't be discussing that one here (as it is ably covered elsewhere in this encyclopedia). But do take note - those old Roco-made Geeps are vastly inferior to all of the subsequent versions (IE, eBay bidders beware).
The first post-Roco Atlas GP30 and GP35 models were manufactured in Japan by Kato. And starting with that first Kato-made release, Atlas has always released these two models in tandem (no surprise there since they share the same basic internals). Anyway, the upshot of all that is that I'm going to save myself a bit of time and cover them both here.
Those first Kato-made units were noteworthy insofar as they were the first Atlas diesel models to come with full pilots and shell-mounted couplers. The Micro-Trains friendly coupler-clip system employed in these models was actually first introduced in Kato's SD40 model of the previous year. Additionally, these two Geeps were the very last collaboration between Atlas and Kato. The two venerable firms were destined to go their seperate ways in the mid-1990s (with Atlas subsequently relocating all of their locomotive production to China).
In addition to the shell-mounted couplers, the rest of the mechanism employs all of the other time-honored design features one normally associates with "modern" Atlas diesels - split-frame metal chassis, dual-flywheels, low-friction drive, plastic truck assemblies, plastic gearing, blackened wheels, all-wheel drive, and all-wheel pick-up (no traction tires). The motor is an open-sided 5-poler. Directional lighting is provided by PC boards mounted on either end of the chassis. The couplers are Rapidos (easily swapped out for MT's). Wheels are low-profile and have no problems on Code-55 track.
Performance on these models is perfect in every way - smooth, quiet, flawless pickup and throttle response, exceptional pulling power, etc.
Starting with this very first release, Atlas has made their GP35 model available in two different "phases" (1A and 1B). I'm told that the differences between the two basically boil down to the number (and location) of the various door latches and hinges (seriously, I am not making this up). I guess the 1A has lots of latches and the 1B has fewer. So, if such things concern you... well, now ya know. Additionally, they're available with or without dynamic brakes (presumably based on the prototype in question).
Atlas re-released these models as part of their "Atlas Classic" line in 1997 (manufactured in China). Normally this line consisted of redesigned/retooled remakes of the earlier Kato-made models. However, as far as I can tell, these "new" models are virtually identical to the older ones. About the only difference I can detect is that the PCB's are green instead of white -
Starting with the 2001 production run, these models came with AccuMate couplers -
Revised (DCC-Ready) versions of these models came out in 2006. They also included Atlas's new "slow speed" motor and "white" LED lighting -
A new "Phase 1" version of the GP30 was issued in 2008 -
The cab on the "Phase 1" version is symetrical, whereas the cab on the previous "Phase 2" versions is 10 scale inches shorter on the left side. Also, the Phase 1 version lacks a handrail stanchion on the left side. Despite the minor shell changes, the chassis/mechanism in the 2008 Phase 1 version is the same as the one used in the 2006 Phase 2 version.
In 2020, Atlas released revised versions of these models. As pictured below, the internals were completely redesigned to include support for an ESU LokSound DCC-Sound decoder and accompanying speaker (analog versions were also part of this release). Instead of using screws and hex nuts to hold the chassis halves together, this new version uses plastic clips on either end of the chassis (the fuel tank and motor saddle also contribute to holding things together) -
Gone are the chassis contact strips that the truck axle-wipers used to rub up against (an Atlas staple since the 1980's). Instead, small wires are soldered to the axle-wipers on the one end and to cylindrical metal plugs (which insert into holes in the chassis) on the other. Note that the plugs are rather tight-fitting, so it's best to push them out from the inside (as opposed to trying to pull them out from the outside).
One oddity with these models are the strips of foamy insulation glued to the outside of the chassis. I'm not sure what purpose all that serves, but maybe the old shells didn't quite fit the new chassis as well as they could? In any case, it's kind of an annoyance when it comes to taking the chassis apart.
The rest of the internals are more or less the same as before. A five-pole / skew-wound motor spins dual flywheels. In turn, the flywheels spin plastic shafts with notched-cups on the worm side. Said cups spin little ball-and-pin connectors on the wormshafts. Bearing blocks inside of notches in the chassis hold the brass worms in place. A long plastic shield is clipped to the top of the chassis (dunno why - but maybe to prevent short circuits between the decoder and chassis?)
I particularly like the way the circuit boards (and contacts thereto) have been redesigned. Very similar to IMRC's SD40-2 of 2017, metal contacts on the motor saddle transfer current from the main PC board (or decoder) to the motor and to the speaker mounted inside the fuel tank (note that even the non-sound locos come with a speaker). Unlike previous Atlas locos, the main PC board slides in and out of its chassis slots without requiring that one first partially disassemble the chassis (a nicety that Kato has offered for years). The design and placement of the new PC board contacts is also an improvement over previous Atlas diesels (where getting the motor contacts to line up with the contact pads on the PC board was admittedly a bit "hit and miss").
All eight wheels provide pickup, all four axles are geared, and all gearing is plastic. The wheels are blackened and low-profile. The trucks and fuel tank appear to be the same as on previous versions. Note that speaker holes in the fuel tank aren't really required since the speaker is positioned such that sound projects upward rather than downward.
AFAIK, there were no changes to the shells with this release (IE, older shells should work with this newer chassis, and vice versa). The shells are all plastic and include separate detail parts for the windows, numberboards, handrails, cab, sidesills, and horn. Couplers are shell-mounted Accumates.
Performance on this new version is every bit the equal of its predecessors. Out of the box, I didn't have any problems with the wheel-blackening causing any sort of jitteriness. They run very quietly, throttle response is smooth, pickup is flawless, slow speed creep is "one-time-at-a-time" and the top-end speed is realistic (IE, not too fast). Pulling power is strong, with mine comfortably able to haul 30+ assorted freight cars through curves on level track. No problems with any of the wheels derailing (even on 9.75" radius curves). Overall, just really superb looking and running models.
The sound on the DCC-Sound versions is well rendered and nicely beefy. The default settings for volume are quite reasonable (IE not overly loud). I didn't notice any difference in performance when operating mine with an analog powerpack (IE, they run equally well using DCC or DC control). As seems to be typical with DCC-Sound models these days, the decoders in these locos are programmed to go through a rather protracted sequence of "start up" shenanigans before they start moving (and with similar behavior when slowing down). To eliminate this nonsense (if you're so inclined), simply set CV124 to 0. Also note that the default behavior is for the sound to be off (IE, put the loco on the rails and it won't make a peep). To turn sound on, hit F8.
One minor annoyance I do have with these models is that the headlight LED lights up the entire cab -
If obnoxious lighting displays like this bug you (as they do me), simply take a small piece of electrical and cover up the top and sides of the LED. This will leave the headlight and number boards lit while minimizing the light show in the cab. Also note that although some of the GP30 shells come with "nose headlight" details, said lights are non-functioning.
Shell removal on these models is pretty simple. Just grab the fuel tank with one hand and the shell with the other. Then just sort of wiggle it up and off.
Grade: A (all versions)
Kato-made GP35 reviewed: 6/92 Model Railroader ("Atlas has again teamed up with Kato of Japan to produce a gorgeous-looking and fine-running locomotive in N scale. The Atlas model closely matches (prototype) dimensions... The models are available in Phase Ia and Ib variations, with or without dynamic brake. Phase Ia has seven sets of latches on the tall engine doors, while Ib has only three sets. For the most part, these locomotives follow previous Atlas/Kato construction methods with a highly detailed styrene body and separate cast slippery plastic handrails to reduce breakage from handling.
"This model's mechanism is a little different than previous four-axle units. The GP35 still uses a pair of cast zinc-alloy frame halves that enclose the motor, flywheels, and worm gears. The truck sideframes are molded in a slippery plastic, and all wheels are used for electrical pickup. However, the trucks have a new wrinkle. They feature needlepoint bearings on the ends of the axles to provide an almost frictionless mechanism. To test the mechanism's rolling qualities, I removed the worm gears so it would roll freely. Then I put it on an inclined track, with a Micro-Trains flatcar on a parallel track, and let them go simultaneously. The engine rolled down the grade faster than the flatcar! Our sample started at 1.5 volts and continued to run smoothly at this low voltage. The locomotive ran quietly until it reached a scale 140 mph, where it began to whine... the model should pull approximately 16 free-rolling cars on straight and level track. The model comes with body-mounted Rapido-style couplers... This well-executed model of a popular locomotive features a fine-running mechanism and crisp detail. N scalers will have to make up some good excuses not to have at least one. Phase Ia: Undec, AT&SF, Conrail, B&O, BN. Phase Ib: Undec, CP, E-L, UP, PRR, N&W. $97.95")
Atlas Classic GP30 Phase 1 reviewed 09/2008 Model Railroader ("Built by General Motors' Electro-Motive Division, the GP30 diesel locomotive was known for its good looks and great performance. This new N scale GP30 lives up to its prototype. Part of the Atlas Classic series, the N scale model is available in a DC or Digital Command Control (DCC) version. The Atlas model's dimensions match drawings of a phase I GP30 in the Model Railroader Cyclopedia vol. 2: Diesel Locomotives (Kalmbach Publishing Co., out of print).
"The Atlas model is built primarily of plastic. All the molded-in detail on the body shell and truck sideframes is sharply defined. Placement of vents, hatches, and other details matches prototype photos. The walkways also feature molded safety tread. The handrails are separately applied and made of Celcon, a flexible engineering plastic. The model's paint is evenly applied with sharp color separation. All lettering is crisp and straight. The Atlas GP30 also has two ownership plates on its frame. Legible under magnification, the plates read "GENERAL MOTORS CORPORATION ELECTRO-MOTIVE DIVISION OWNER."
"The die-cast metal split-frame chassis encases the motor and two brass flywheels. The five-pole skew-wound motor turns two worm gear shafts that transfer power to gearboxes above each truck. The printed-circuit (PC) board is mounted above the split frame. Golden white light-emitting diodes (LEDs) mounted on each end of the PC board illuminate the headlights and number boards. The headlights turn on and off according to the locomotive's direction, which isn't prototypical.
"Our DC-only sample has a low starting speed of 1.5 scale mph at 2.5 volts. The model has a top speed of 116 mph at 12 volts. Depending upon its gear ratio, the prototype's top speed was about 80 mph. Throughout the speed range the Atlas GP30's mechanism was smooth and quiet. I ran the model around 93/4" curves and through no. 4 turnouts without difficulty. The model has a .8 ounce drawbar pull equivalent to 19 average N scale freight cars on straight and level track. With smooth performance and accurate details, the Atlas Classic Series GP30 is a great choice for an N scale diesel roster.")