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Athearn SD9 mechanism for a Studio Scale Models Sulzer.

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patrick
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I have been working on modifying an Athearn blue box SD9 underframe for a SSM Sulzer. One of the fuel tanks was removed to shorten the wheel base and the remaining tank and SSM fuel tank castings were ground down to fit. A friend of mine who is a tool and die maker made quick work of this although it could be done with a file. The frame was then glued back together with epoxy using thick plasticard to brace it along the sides. The gears were removed from one of the bogies but the metal wheels were retained for electrical contact. One of the Athearn flywheels was retained. It may be possible to keep the 12 wheel drive but not with a flywheel and possibly a shorter motor would have to be substituted. The Athern bogies pick up current on one side and send it up through the metal tabs on each bogie. One of these was bent to clear the flywheel. On the other side the current is transferred to the locomotive frame. The original motor mount allows it to pick up current through a copper contact on the underside which makes contact with the frame however in order to have room for the flywheel I altered the motor position and then used wire to make all electrical contacts with contacts on the bogies. The motor was mounted using silicon and some scrap plasticard, an idea I got from Model Railroader years ago. This holds the motor tight enough to operate but it can easily be removed if necessary. The mechanism runs well but typical of the Athearn blue box diesels is a little noisy. Because the flywheel is on the side of the unpowered bogie limiting traction, fishing lure weights were add on the power bogie side and in the locomotive shell. As can be seen from one of the photos the locomotive body sits slightly high on the mechanism but this can be easily fixed by removing o little material from the inside of the shell. I took a little experimenting to get everything working and unfortunately when it was all assembled it runs backwards! To fix this the bogies will have to be reversed and while I am at it the wiring will be tidied up.

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I used the old Athearn SD9 mech as a basis for motorising an A Class and found it easier to fabricate a frame from KS Brass box section and strip than trying to shorten the Athearn die-cast frame. I managed to keep the drive to both trucks by removing one of the flywheels & mounting the motor low between the frames. Diesel frame.jpg

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