Atlas O F2/F3 diesel

With the distinctive rumble of a 567 diesel engine, this O scale F2A replicates the sounds of a first-generation EMD F unit. The Atlas O model features a QSI Quantum sound system with programmable effects in both DC and Digital Command Control (DCC) modes.

The prototype. Beginning with the FT in 1939, the F units built by General Motors’ Electro-Motive Division were the first successful road freight diesels designed for mass production. Electro-Motive produced F2 A and B units from July to November 1946. The F2 was a transitional model between the FT and the F3 diesels. (The F2 had a 1,350-hp engine, compared to the F3’s 1,500-hp power plant.)

Modelers and railfans use the term “phases” to describe the detail changes that occurred during F3 production. Externally the F2 looks identical to a phase I F3. Key spotting features of an F2/F3A include high radiator fan shrouds, small rear air-intake openings, square corner doors, and center portholes on the body.

Appearance. All the Atlas O model’s dimensions match drawings of a Phase I F3 found in the Model Railroader Cyclopedia: Vol. 2 Diesel Locomotives (Kalmbach Publishing Co., out of print).

The Atlas O F2 has a plastic body shell with molded and separately applied details that match prototype photos. All the grab irons are metal. The dynamic brake screens and radiator vents are see-through. Underneath the vents are separately applied fans.

Our review sample came painted in the Boston & Maine’s maroon and gold “Minuteman” paint scheme, which was first applied to B&M cab units in 1945. The railroad purchased its F2s in 1946 and the Atlas O model matches prototype photos, including the “Minuteman” herald on its nose.

Matching B units are available for the B&M version. When coupled together the A and B units are prototypically spaced with their diaphragms touching.

Drivetrain and electronics. I removed four screws under the chassis and lifted off the body shell. At each end a can motor with a flywheel transfers power to a gearbox above each truck. A printed-circuit (PC) board with the DCC decoder mounted on top of it is between the trucks. The speaker for the sound system is mounted in the fuel tank.

The fuel tank, trucks, and chassis are die-cast metal. The hefty Atlas O F2 has a drawbar pull equivalent of 55 O scale freight cars on straight and level track.

The dual-mode QSI Quantum sound decoder operates well and offers realistic sound on DC as well as DCC layouts. Along with the realistic rumble of the diesel engine, I triggered the horn and bell using the direction button of the power pack in our shop.

As outlined in the included instruction manual, you can program many of the decoder’s features in DC using only a power pack. Programming of the QSI Quantum sound decoder is made even easier if you use a QSI Quantum Engineer analog DC controller (sold separately).

Programming also was easy in DCC. I changed the F2’s long address to its locomotive number. An extensive list of CVs controlling sound and motor performance are also programmable.

Sound effects include the air horn and prime mover. The diesel engine rpm sounds shift through all eight throttle notches.

Speed tests. The Atlas F2 performed well in both DC and DCC modes. Out of the box the model is factory programmed in Regulated Throttle Control (RTC). This gives the F2 realistic momentum when accelerating and decelerating. For our speed tests, I set the model to Standard Throttle Control (STC), which makes the model respond immediately to throttle adjustments. The instructions outline how to switch between RTC and STC in both DC and DCC modes.

In DC the model started moving at 4.5 scale mph at 8.5 volts and accelerated to 82 scale mph at 12 volts. Slow speed performance was better in DCC using 128 speed steps, as the model crawled at 1.5 scale mph in speed step 1 and again reached a top speed of 82 scale mph, which is close to that of one of the prototype’s gear ratios offered by EMD.

The Atlas O F2 is a smooth performer in both DC and DCC. Its great sound system makes the O scale F unit a lot of fun to operate.

O scale F2/F3 diesel
Price (single A or B unit): $419.95 (DC), $479.95 (DCC), $199.95 (unpowered)
Manufacturer
Atlas O
378 Florence Ave.
Hillside, NJ 07205-1799
www.atlasO.com
Description: Ready-to-run plastic and metal diesel
Road names: (two road numbers each) Boston & Maine; Chicago, Burlington & Quincy; Lackawanna; New York Central; Rock Island; Southern Ry.; and undecorated (single- and double-headlight versions)
B units for B&M, Lackawanna, SR, and undecorated

Atlas O F2/F3 features
All-wheel drive and electrical pickup
Blackened metal RP-25 contour wheels in gauge
Die-cast metal magnetic knuckle couplers at correct height Drawbar pull: 1.2 pounds
Dual-model Digital Command Control decoder (DCC version only)
Dual can motors and flywheels
Minimum radius: 36″
QSI Quantum sound system (DCC version only)
Weight: 3.75 pounds