The NEW American Flyer/Lionel SD-9
Completely (almost) new Power Truck design

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For 2005  Lionel has redesigned the SD-9 and Alco PAs chassis and drive train.  The frames and power trucks are  much smoother and quieter running than the former made-over AC Gilbert design
The SD-9 has a new side frame casting representing the prototype. The unit is not a true scale model and still uses the short GP chassis as it's basis and is 1.25" shorter than a scale model. 

There are now Six wheels, the center set is  driven from the motor and the spur gears drive the outer wheels.  
The power pickup has a set of new roller assemblies on each side and on each truck. They work on my American Models track and turnouts without any problems. One may have to exercise them a bit to flex their wire so they are not too stiff. but that is a minor problem.
The truck is held on the motor mount with two screws and is easy to service.

One problem I encountered was that one unit had a bit of runout on one of the insulated wheels creating a bit of a wobble as it went down the track. This is  inherent in the design of the insulated wheels which are a hold over from the legacy AC Gilbert design. 
The motor has a generous flywheel and uses a worm drive. Unfortunately it is a double start worm and the gear ratio is only 11:1 from the motor to wheels. A single start worm would have improved the low end speed in my opinion. 

If Lionel would have slightly enlarged the well hole for the dummy truck to match the one for the power truck one could have easily made both trucks power trucks. There is room in the body to clear the second motor.


The gear train is nicely done and of good quality and  easy to service and lubricate.

There are two traction tires per power truck.

The SD-9 Drawbar pull is 8 ounces.

The  Alco PA Drawbar pull is 12 ounces.

In conclusion these are  much improved from the  previous issues. Perform nicely and are quiet running. 

I will convert both the PAs and SD-9s to TMCC and Sound.

Here are pictures of the prototypes for the two SD-9s for 2005