BMW R 12
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The BMW R 12 was a motorcycle produced by Bayerische Motoren Werke in 1935 and is considered the most popular pre-war motorcycle by BMW. The trailblazer on the R 12 and the BMW R 17 , which appeared at the same time, was the first hydraulically damped telescopic fork in motorcycle construction.
history
On February 14, 1935, BMW presented the R 12 together with its sporty sister model R 17 to the public for the first time at the German Motor Show in Berlin as the successor to the R 11 . With a sidecar, the R 12 was the standard team of the Wehrmacht in World War II, albeit less well known than the BMW R 75 . For military use it was only supplied with a single carburetor engine. By 1942, 36,000 R 12s had been built in Munich.
technology
engine
The engine with the designation M 56 S 6 or 212 was built as a two-cylinder along Boxer - four-stroke engine with vertical valves designed. The R 12 with two carburetors was equipped with a battery ignition , while the "authorities machine" with the single carburetor system was equipped with a magneto ignition that worked independently of the battery.
drive
The R 12 had a four-speed claw-shift gearbox with manual transmission on the tank and a helical, “noiseless” fourth gear; the drive shaft ran on the right side of the unsprung rear wheel.
BMW referred to the power transmission from the gearbox to the rear wheel as a " cardan drive ", the drive shaft as a " cardan shaft " and the gearbox on the rear wheel as a "cardan housing" - technically correct it was only a shaft drive of the rear wheel, as there were no cardan joints.
Chassis and brakes
The rear-wheel drive was redesigned with a fixed quick-release axle so that the wheels were interchangeable. The previous cardan brake was omitted, instead all wheels had drum brakes.
Technical specifications
| Parameter | R 12 with one carburettor | R 12 with two carburetors |
|---|---|---|
| drilling | 78 mm | |
| Hub | 78 mm | |
| Displacement | 745 cc | |
| Compression ratio | 5.2: 1 | |
| power | 18 hp (13.2 kW ) at 3400 min -1 | 20 hp (14.7 kW ) at 4000 min -1 |
| Top speed | 110 km / h | 120 km / h |
| Empty weight | 162 kg | |
| Tank capacity | 14 liters | |
For later versions of the R12 with a carburetor BMW was 18 hp at 3400 min -1 as a continuous power and 20 HP as the maximum power at 4000 min -1 at.
The BMW R 12 in the museum
In the Army History Museum in Vienna , in the permanent exhibition “Republic and Dictatorship” (Room VII), there is a BMW R 12 that was in service with the German Wehrmacht during the Second World War . The motorcycle was the device of a motorcycle reporter , survived the war and still has the original camouflage .
See also
Web links
- BMW R 12. In: BMW History. BMW AG, accessed on December 9, 2015 (dossier of the BMW Group Archives).
- Manual for BMW two-cylinder models Type R 12 750 cc touring, Type R 17 750 cc Sport. In: BMW history. BMW AG, March 1935, accessed on December 9, 2015 (manual with pictures, 43 pages).
Individual evidence
- ↑ BMW R 12 sectional drawing of the telescopic fork. In: BMW history. BMW AG, 1935, accessed on December 9, 2015 (drawing in the BMW Group archive): "BMW works drawing"
- ↑ BMW presents the world's first hydraulic telescopic fork on the R 12 and R 17 models. In: BMW history. BMW AG, February 14, 1935, accessed on December 9, 2015 (text in the BMW Group Archive).
- ^ Wolfgang Zeyen and Jan Leek: BMW - The motorcycles since 1923 . Motorbuch Verlag, Stuttgart 2004, ISBN 3-613-02401-2 , pp. 71-73, 87 u. 88
- ↑ a b BMW R 12 twin carburetor. In: BMW history. BMW AG, accessed on December 9, 2015 (dossier in the BMW Group archive with technical data).
- ↑ a b BMW R 12 single carburetor. In: BMW history. BMW AG, accessed on December 9, 2015 (dossier in the BMW Group archive with technical data).
- ↑ a b c d The innovations on the BMW machines in 1935 . In: BMW (ed.): BMW sheets . 100,000 circulation. No. 22 . Berlin February 1935, p. 12–15 ( bmw-grouparchiv.de [PDF; accessed on December 8, 2015] in-house communications from Bayerische Motoren-Werke AG).
- ↑ Spare parts list for the BMW motorcycles type R 12 (750 ccm touring model) / type R 17 (750 ccm sports model). In: BMW history. BMW AG, May 1935, accessed on December 8, 2015 (spare parts list with pictures, 97 pages).
- ↑ Manual for the BMW R 12 750 ccm motorcycle. In: BMW history. BMW AG, January 1942, accessed on December 9, 2015 (manual with pictures, 78 pages).
- ^ Manfried Rauchsteiner , Manfred Litscher (Ed.): The Army History Museum in Vienna. Graz, Vienna 2000 p. 82.
| class | Type | 1920s | 1930s | 1940s | ||||||||||||||||||||
| 3 | 4th | 5 | 6th | 7th | 8th | 9 | 0 | 1 | 2 | 3 | 4th | 5 | 6th | 7th | 8th | 9 | 0 | 1 | 2 | 3 | 4th | 5 | ||
| up to 250 cm³ | Touring motorcycle | R 2 | R 20 | |||||||||||||||||||||
| R 23 | ||||||||||||||||||||||||
| Sport motorcycle | R 39 | |||||||||||||||||||||||
| up to 500 cm³ | Touring motorcycle | R 32 | R 42 | R 52 | R 4 | |||||||||||||||||||
| R 3 | R 35 | |||||||||||||||||||||||
| Sport motorcycle | R 37 | R 47 | R 57 | R 5 | R 51 | |||||||||||||||||||
| up to 750 cm³ | Touring motorcycle | R 62 | R 11 | R 12 | R 71 | |||||||||||||||||||
| R 6 | R 61 | |||||||||||||||||||||||
| Sport motorcycle | R 63 | R 16 | R 17 | R 66 | ||||||||||||||||||||
| Prototypes, racing bikes | R 7 | |||||||||||||||||||||||
| WR 750 | R 51 RS | |||||||||||||||||||||||
| Military motorcycles | R 12 | |||||||||||||||||||||||
| R 75 team | ||||||||||||||||||||||||
