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As mopeds became increasingly popular, manufacturers competed to provide customers with more and more advantages. Sales arguments often focussed on engine characteristics. Engines should be reliable and have good pulling power, so you didn’t need to tread the pedals. Preferably, the moped should have a kick-starter, so you didn’t need to cycle to start up. Low fuel-consumption was of course also desirable. Other considerations were compact and attractive design.

These pages show various types of transmission which were intended to contribute to bringing about some of the characteristics mentioned above.

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The non-visible part of the transmission is usually enclosed within the engine. It gradually became the norm to have a primary drive consisting of a small and a large sprocket. The clutch was often mounted on the output axle. (Rex, Zündapp, SCO)

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Zündapp KM 48 from 1954 with a single gear and external clutch. Note that the gear was lubricated by the oil-mixed petrol.

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SCO Type1 from 1955 with a single gear and external clutch.

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On mopeds, with the above-mentioned engine types, it was also necessary to have ordinary chain-drive from pedals so that the bike could be started using these. Diesella wished to avoid having two external chain-drives, so they placed the crank axle within the engine. It was also considered good sense in connection with marketing to avoid having chain-drive within the engine. For the same reason, it was decided to have an internal clutch. These considerations led to the rather imaginative construction shown below, with planet gears and a cone clutch - all integrated in a single unit. It seems, however, that the idea for this construction came from France.

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Diesella type 118 engine from 1955. Cutaway view.

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Patent DK 81545: Drive mechanism for bicycles of the kind where the chain drive on the bike’s pedal axle can be driven either by an auxiliary motor or from the pedals via a free-wheeling mechanism (1951). Inventor: Manufacturer René Henri Briban, Patin, Seine, France

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Cutaway view of the Diesella type 118 engine.

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This illustration gives a clear view of the Diesella 118 conus clutch.

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