As AC traction motor technology improved in the 1990s, the SD70MAC emerged as ideal power for heavy trains.
Billed as the biggest technological development since the switch from steam to diesel, improvements in AC traction motor technology promised major changes in how railroads ran trains and assigned power.
Diesels with conventional DC traction motors can develop a lot of power at low speed, but only for a short period of time before the motors will overheat. AC traction motors on the other hand can run at full power without overheating for a long time. This gives AC motored locomotives an advantage in hauling heavy drag freights like coal trains. After testing EMD’s SD60MAC prototypes, Burlington Northern determined they could replace five aging SD40-2 and C30-7 locomotives with just three new SD70MACs on their Powder River Basin coal trains. Burlington Northern’s initial order for 350 SD70MACs brought AC traction to the spotlight in a big way.
Along with the AC motors, the SD70MAC featured improved anti-slip control which greatly improved the locomotives’ adhesion. In other words, the SD70MAC didn’t pull more because it was more powerful, it pulled more because it made better use of the power it produced. The SD70MACs could dig in and pull when conventional locomotives just spun their wheels. It wasn’t long before other railroads were trying out AC as well.
While Burlington Northern and most of the other railroads which purchased the SD70MAC did so for coal and other heavy drag freight trains, the locomotives often wander into other service corridors as well. Unit grain trains and general merchandise are common assignments. Perhaps most unusual are those on the Alaska Railroad which sometimes find themselves pulling passengers.
Our latest release brings the model up to date with today’s LEGACY control and other great features, including:
- LEGACY Control System – able to run on LEGACY, TMCC or Conventional control layouts
- Odyssey II Speed Control with On / Off switch
- LEGACYRailSounds including
- CrewTalk andTowerCom dialog
- 6 Official railroad speeds
- 8 Diesel RPM levels
- Quilling Horn
- Bell (single hit and continuous)
- Sequence Control
- Current speed and fuel dialog
- Refueling sounds
- Dual maintenance-free motors
- Traction Tires
- Refined Conventional Control mode with lower starting speeds
- Front and Rear ElectroCouplers
- Fan-driven smoke with adjustable output
IR Transmitter (works with the new SensorTrack)
- Directional lighting
- Marker Lights
- Lighted cab interior with crew
- Many separately applied metal detail parts
- Metal frame, pilots, trucks and fuel tank
- Minimum Curve – O31
Another notable improvement over previous SD70MAC runs, we’ve lowered the fuel tank to a more realistic appearance.
The SD70MAC is being built to order. They were presented in two road numbers for Alaska, Burlington Northern, BNSF, CSX, and Kansas City Southern (one in the gray and one in the Southern Belle scheme). A Conrail SD70MAC is available as part of the Big Blue Auto Parts Boxcar Set and as a single number for separate sale. Look to see them later this year at your local Lionel dealer with a suggested retail price of $549.99.