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Broadway Limited Imports, HO scale, 4-8-8-2 Cab-Forward

Reviewed in the August 2004 issue
RELATED TOPICS: LOCOMOTIVE - STEAM | HO SCALE
HO 4-8-8-2 Cab-Forward
The HO 4-8-8-2 Cab-Forward from Broadway Limited Imports is a mountain climber with great sound effects.
This great-looking HO scale Southern Pacific class AC-4 Cab-Forward 4-8-8-2 comes with sound and an automatic dual-mode Digital Command Control (DCC) decoder that operates on DCC or DC layouts. The model will negotiate curves as sharp as 22" radius. It's the latest steam locomotive introduced by Broadway Limited Imports.
The three circular openings below the AC-4's cab were filled in during the 1930s, while the number boxes were revised about 1950.
Cab-Forward basics: Southern Pacific's Cab-Forward articulated steam locomotives were built to operate through the Sierra-Nevada Mountains between Roseville, Calif., and Sparks, Nev. This rugged mountain district included 139 miles of main line with steep grades, 39 tunnels, and nearly 40 miles of snowsheds to keep the line open through the heavy snowfalls.

Crews running conventional locomotives in these confined spaces were faced with hot steam and exhaust gases that filled the cabs and could asphyxiate them. Turning the locomotive around put the cab and crew ahead of the exhaust gases, which alleviated the problem and created a unique SP locomotive. These locomotives burned bunker C oil that was heated and pumped forward to the firebox oil burner.

Southern Pacific designated the cab as the front end. Interestingly, the left- and right-side designations followed conventional practice looking toward the smokebox from the cab end.

Early Cab-Forwards were relatively slow, so the SP was looking for more speed and tractive effort when it purchased ten class AC-4 4-8-8-2 locomotives from Baldwin in 1928. They were followed by a second nearly identical group of locomotives, class AC-5 nos. 4110-4125, built by Baldwin in 1929.

Each locomotive and tender weighed 453 tons and developed 116,900 pounds of tractive effort. Both classes had cylindrical tenders that carried 16,152 gallons of water and 4,889 gallons of oil.

The AC-4s and AC-5s were initially assigned to the Sierra crossing until they were displaced by even more-powerful Cab-Forwards. In later years, they also saw service on other parts of the SP system.
The model has an unrealistic opening beneath the firebox that could be filled by adding the sloping firepan used with the prototype's oil burner.
The model captures the overall look and proportions of the prototype. Most of its dimensions follow prototype plans published in the June 1985 issue of Mainline Modeler, except for the overall length which BLI extended to provide clearance for operation on tight curves.

The boiler is about a scale 30" too long, and the 67'-6" wheelbase is about a foot long. The additional clearance is worked into each engine's driving wheelbase and around the forward cylinders, but it isn't obvious.
Gently prying off the cab roof and the steam dome gives access to the two screws which attach the top half of the boiler to the mechanism.
Double truck design: Prototype AC-4s had their front engines (under the firebox) rigidly attached to the boiler, while a hinged joint allowed the rear engine to move from side to side under the smokebox. In contrast, this model has a more flexible "double truck" mechanism similar to other recent articulated models. Both engines swivel under the boiler to reduce the overhang at both ends on model curves as sharp as 22" radius.

A can motor and a pair of flywheels are mounted in the middle of a heavy metal weight that fills most of the boiler. A printed circuit board that includes connections for a Seuthe smoke unit is mounted on top of the weight.

Each eight-drivered engine is made like a diesel truck with a vertical gearbox above the main drivers (the ones carrying eccentric cranks). Universal shafts at the top connect them to the motor shafts. Both engines swivel and rock slightly under the boiler to ensure that all of the drivers contact the rails for maximum tractive effort.

The well-detailed lead and trailing trucks are mounted on extensions of the engine frames.
The tender holds a factory-installed Quantum sound system with dual speakers and a volume control.
The cylindrical tender has a detailed plastic body shell which matches the prototype plan right down to the pressure cap on the oil tank. A die-cast metal underframe is secured by four screws, and the tender rides on Commonwealth six-wheel trucks.

In DCC mode, the sound system produces chuffing that goes in and out of step to simulate independent exhausts (though the wheels don't vary). Function keys actuate the whistle, bell, and other sounds. A doppler effect is built in, along with automatic changes in the chuffing to simulate different loads.

The locomotive and tender were smoothly spray-painted in black, silver, and graphite gray with nice, clean color separations. All of the lettering is sharp and opaque.
Performance. The AC-4 model started and ran smoothly at less than 2 mph on both DC and DCC. Like previous BLI models, this locomotive's sound system starts at 5 volts DC, and the locomotive begins moving at 9 volts. This higher-than-usual starting voltage can be reprogrammed to a lower starting voltage that increases the control range. Even so, the AC-4 still attains passenger speeds at 12 volts.

On DCC, the model's fine performance continued and was further enhanced by the sound effects. The locomotive's operation at normal freight speeds was excellent. Its 5.6-ounce drawbar pull is equivalent to 78 free-rolling freight cars on straight and level track.

I was happy to see regular Kadee magnetic couplers properly mounted at the correct height on both ends of this model. They're insulated so it's possible to doublehead the AC-4 on a heavy train.

I'm impressed with the detail and performance Broadway Limited Imports has built into this unusual locomotive. It's a powerful model that'll look great forwarding an eastbound refrigerator train of produce.
HO 4-8-8-2 Cab-Forward
Price: $499.99 each

Manufacturer:
Broadway Limited Imports
601 Shenandoah Village Drive
Suite 9 E/F
Waynesboro, VA 22980
540-949-8300
www.broadway-limited.com

Description:
Plastic-and-metal ready-to-run
articulated steam locomotive
with sound

Features:
Cab interior with backhead
Constant directional headlights
Die-cast metal chassis
Drawbar pull: 5.6 ounces
Dual-turned brass flywheels
Engine and tender weight:
36.5 ounces, engine alone is
30 ounces
Firebox glow
Five-pole can motor
Illuminated number boards
Kadee magnetic knuckle
couplers at both ends
Minimum radius: 22"
Operating deck plate between
engine and tender
RP-25 contour wheels (in
gauge)
Seuthe smoke unit ready

Road Names:
(All Southern Pacific)
AC-4 nos. 4100 or 4106, and
painted without lettering
AC-5 nos. 4111 or 4120, and
painted without lettering

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