BMW R 7
The BMW R7 is the prototype of an unrealized motorcycle from BMW with two-cylinder four-stroke - boxer engine and shaft drive from the year 1934th
history
The engineer Alfred Böning designed and built the R 7 in 1934. Another new feature was the boxer engine designed by Leonhard Ischinger, which was to be designed in three versions, 500 to 800 cm³.
The design did not go into series production - BMW decided to build Rudolf Schleicher's sportier design , the BMW R 5 with a welded tubular frame instead of a lavish pressed steel frame.
technology
The smooth-surfaced design pursued a concept that combined elements of the Art Déco and the streamlined age .
engine
The completely newly developed engine "205/1" was designed as a longitudinally installed two-cylinder boxer four-stroke engine with overhead valves . Only individual elements of the engine were followed up.
For example, only in this prototype cylinder and cylinder head were cast as a unit from one piece in order to avoid the vulnerable cylinder head gasket. The design feature of the camshaft located under the crankshaft, which significantly reduced the overall height of the boxer, was only taken up again by BMW in the so-called "dash five" series from 1969 onwards.
A one-piece forged crankshaft rotated in the one-piece tunnel housing. The connecting rod bearings were split and ran on plain bearings.
drive
The R 7 had a manual gearbox with shaft drive on the right side of the unsprung rear wheel.
landing gear
A telescopic fork was used for the first time on a BMW motorcycle. The R 12 and R 17 were then equipped with it in series production. The frame was designed as a pressed steel frame .
Technical specifications
| Parameter | Data of the R 7 |
|---|---|
| Engine type | air-cooled 2-cylinder boxer engine |
| Valve control | OHV, 2 valves per cylinder |
| drilling | 78 mm |
| Hub | 83 mm |
| Displacement | 793 cc |
| power | 35 hp (26 kW ) at 5000 min -1 |
| Empty weight | 178 kg |
See also
Web links
- BMW R 7. In: BMW History. BMW AG, accessed on March 1, 2017 (dossier of the BMW Group Archives).
Individual evidence
- ↑ The R 7 - The Art Deco Treasure. BMW Motorrad, March 17, 2013, accessed March 2, 2017 .
- ↑ BMW R 7 prototype drawing. In: BMW history. BMW AG, 1934, accessed on March 2, 2017 (drawing in the BMW Group Archive): “Prototype R 7, first telescopic fork (adopted for R 12 and R 17), newly developed engine with camshaft underneath the crankshaft, pressed steel frame. Also referred to as R 5. In favor of the tubular frame R 5 did not go into series production. "
- ↑ 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 March 2, 2017 (text in the BMW Group Archive).
| 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 | ||||||||||||||||||||||||
