BMW's motorcycle history began in 1921 when the company commenced manufacturing engines for other companies. BMW's own motorcycles—sold under the BMW Motorrad brand—began in 1923 with the BMW R 32, which was powered by a flat-twin engine (also called a "boxer-twin" engine). Production of motorcycles with flat-twin engines continues to this day, however BMW has also produced many models with other types of engines.  At the end of World War I, the Treaty of Versailles demanded that BMW cease production of aircraft engines. To remain in business, the company began producing small industrial engines (along with farm equipment, household items and railway brakes). In 1920, BMW M2B15 flat-twin petrol engine was released. Despite being designed as a portable industrial engine, the M2B15 was also used by several motorcycle manufacturers, including for the 1920–1923 Victoria KR1and the 1920–1922 Bayerische Flugzeugwerke (BFw) Helios motorcycles.   BMW merged with Bayerische Flugzeugwerke in 1922, and the BFw Helios became the starting point for the first BMW motorcycle.[1][2] Released in 1923, the BMW R 32 used a 486 cc (29.7 cu in) flat-twin petrol engine,[3] which was longitudinally-mounted to eliminate the cooling problems of the transversely mounted engine in the Helios. This engine with 6.3 kW (8.5 hp), resulting in a top speed of 95 to 100 km/h (59 to 62 mph).[4] At a time when many motorcycle manufacturers used total-loss oiling systems, the new BMW engine featured a recirculating wet sump oiling system with a drip feed to roller bearings; a design which BMW used until 1969. The R 32 also started the tradition of shaft drive, which was used on all BMW motorcycles until 1994.