HO Twin

Horizontally Opposed Twin

Examples include BMW, Zundapp and Douglas HO Twins have conrods running on a common crank, with one on the exhaust stroke and the other on inlet.
Cardan

Shaft Drive

Examples include BMW, Zundapp and Velocette LE Cardan drive eliminates chain and associated mess and maintenance. Often referred to as a "diff", the final drive unit consists of bevel crown and pinion gears.

BMW Motorcycles

BMW R-17 1935

BMW R-17 1935-1937 735cc

Production years: 1935-1937
Power: 33 CV at 5000 rpm
Capacity: 735cc
Engine: Boxer 4-stroke, overhead valve
Transmission: Cardan
Maximum speed: 140 Km/h
Units produced: 434
Weight: 183 Kg

In 1935 BMW introduced two models with telescopic forks, the R-12 and the R-17, the production motorcycles incorporating oil-dampers in the front fork. The R-17 is the sports version.

BMW R-17 at the 1936 Olympia Show