BMW M2B15
| BMW | |
|---|---|
 Motor M2B15 in the Deutsches Museum - the illustration shows a version with a propeller for aircraft |
|
| M2B15 | |
| Production period: | 1920-1923 |
| Manufacturer: | BMW |
| Working principle: | Otto |
| Motor design: | 2-cylinder boxer engine |
| Valve control: | SV valve control |
| Displacement: | 494 cm 3 |
| Mixture preparation: | Carburetor |
| Engine charging: | sucking free |
| Power: | 4.8 kW |
| Dimensions: | 31 kg |
| Previous model: | none |
| Successor: | none |
The BMW M2B15 was an SV two- cylinder boxer engine from BMW with a displacement of 494 cm³. The two-cylinder, also known as the “Bayern Kleinmotor”, which was mass-produced from 1920 to 1923, was the company's first motorcycle engine. Originally it was intended as a portable industrial engine.
history
Engineer Max Friz joined BMW in 1917 , where he first developed a new six-cylinder aircraft engine. The resulting BMW IIIa engine was built into the Fokker D.VII and played a major role in the aircraft's good performance. After the further development of aircraft was forbidden in Germany after the end of the war due to the Versailles Treaty , BMW developed, among other things, a replacement. Interest in motorcycles.
In 1920, Friz copied and reworked the engine from his Douglas motorcycle together with foreman Martin Stolle . Before that, Stolle had built six test engines based on this model. Because of the smoothness and the higher power output, Stolle considered two cylinders to be necessary. The 500 cm³ boxer engine developed in this way was named "BMW M2 B15", where "2" stands for two cylinders and "B" stands for boxer engine.
The engine was used by several German motorcycle manufacturers to power their vehicles. The largest customer was the Victoria-Werke for their model KR 1 and other customers, among others. Bison , Corona , Heller , Karü and SMW . The Bayerische Flugzeugwerke used the engine in the Helios . The short-lived automobile manufacturer Atlantic powered the Atlantic single -track car with the M2 B15 .
According to the manufacturer, the engine was also installed in aircraft on a trial basis "with only moderate success".
The engine later formed the basis for the engine of the BMW R 32 .
technology
The two-cylinder boxer engine with 494 cm³ displacement is air-cooled . Like its model from the Douglas motorcycle, it has SV control (side-mounted valves) and 68 mm bore and stroke each . In the Helios, the boxer engine was installed transversely , that is, the crankshaft was perpendicular to the direction of travel, the cylinders were longitudinal. The power is specified with 6.5 HP, the speed with 3000 / min. Martin Stolle himself mentioned 6.5 hp at 2800 rpm. Power was transmitted to the rear wheel via a single-disc clutch, a manual three-speed gearbox and a roller chain.
Web links
Individual evidence
- ↑ a b c d BMW M 2 B 15 "Bayern-Kleinmotor". In: bmw-grouparchiv.de. Retrieved March 15, 2021 .
- ^ Jan P. Norbye: BMW - Bavaria's Driving Machines . Beekman House, New York 1984, ISBN 0-88176-193-1 , pp. 15 ( archive.org ).
- ^ Zeyen, Leek: BMW motorcycles since 1923 . Motorbuch Verlag, Stuttgart 2004, ISBN 3-613-02401-2 , pp. 20-22.
- ^ Ian Faloon: The BMW Boxer Twins Bible: All Air-Cooled Models 1970-1996 (Except R45, R65, G / S & GS) . Veloce Publishing, Poundbury 2009, ISBN 978-1-84584-168-3 , pp. 6–7 (English, full text / preview in Google Book Search).
- ^ A b Ian Fallon: The Complete Book of BMW Motorcycles: Every Model Since 1923 . Motorbooks, 2020, p. 11 (English, full text / preview in Google book search).
- ^ Mick Walker: How to Restore Your BMW Twin, 1955–1985 . Motorbooks, 2005, pp. 9 (English, full text / preview in Google book search).
- ^ Vorchdorf motorcycle museum. In: motorradmuseum-vorchdorf.at. Retrieved May 1, 2021 .
- ↑ Ian Faloon, 2009, p. 7.
- ↑ Photo: Victoria KR1 with longitudinally installed BMW 2-cylinder boxer engine with 494 cccm displacement, 6.5 hp at 2,500 rpm. (enlarged). In: 7-forum.com. Retrieved May 2, 2021 .
- ↑ Frank Rönicke : The BMW boxer and other constructions. From the notes of Martin Stolle . Podszun, Brilon 2013, ISBN 978-3-86133-689-1 , page 16.
- ^ Wolfgang Zeyen, Jan Leek: BMW motorcycles since 1923 . Motorbuch Verlag, Stuttgart 2004, ISBN 3-613-02401-2 , p. 20th ff .