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Just two steps off the main road, I ran across these little HO engines while rummaging through old boxes. Created in the mid 1970's and patterned after a mid-1920 engine, this very tiny Mack locomotive was designed as a shuttle vehicle on American railways. The problem was motorisation, and I was commissioned by the company to develop a system allowing extremely low speed mixed with enough torque to pull at least 3 freight or passenger cars. A daunting challenge, since the only available space was... inside the cabin!

I also desperately wanted to create a smaller motor than the Mabuchi ST-020 as used in the Tyco, Cobramite and Riggen cars. So I built two prototypes made of sheet brass, with a seriously cut-down ST-020 geared as short as possible, to make it rev as high as possible while providing very low speed. The first one, using a total of six gears, was geared too tall at 8/1, so I devised an 11-gears 18/1 ratio using Aurora HO gears from T-jet cars, in two rows of reductions.

It worked quite satisfactorily and performed as desired. But when the manufacturer was confronted with the cost of building the smaller motor, he baulked and the project was dropped. It is really too bad as this motor could have powered many HO cars, reducing the bulk to a point where exact-scale bodies could have been used instead of the pregnant examples "gracing" almost every HO car produced in the past 30 years.
Too bad indeed... They still work when power is applied.

Dr. Pea

If You don't write all this down in a book I will have to come to America and do it!

Great pictures P, tell us more as history is so interesting.

Best wishes,

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