Both the A-3 switcher with tender and the A-3a saddle tank have the same mechanism with only slight variations in the frames. As produced by Arbour (Bowser) the small motor and gears yielded speeds in excess of 120 SMPH. Replacing these with a Sagami 10153 motor and a variation of the 108:1 double gear reduction setup, the resultant speed is less than 20 SMPH. The motor fits easily on either frame with the plate and shims as shown. Unfortunately there is not enough room for a flywheel. >
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Drawing of essential drive train parts.
For details in making PILLOWBLOCK MOUNT.
