BMW WR 750
| BMW | |
|---|---|
 BMW WR 750 (1929) |
|
| WR 750 | |
| Manufacturer | BMW |
| Production period | 1929 to 1935 |
| class | motorcycle |
| design type | Racing motorcycle |
| Racing series | 750 cc class |
| Motor data | |
| Two - cylinder boxer engine with OHV valve control and compressor | |
| Displacement (cm³) | 735 cc |
| Power (kW / PS ) | 100 PS (74 kW) with methanol , boost pressure 2 bar |
| Top speed ( km / h) | 256.046 |
| transmission | 4-speed |
| drive | Cardan |
| Empty weight (kg) | 149 kg |
| successor | BMW 500 compressor |
The BMW WR 750 was a racing motorcycle from BMW with two-cylinder - four stroke - boxer engine , which was used from 1929 to 1935 for record attempts.
history
The designer of the BMW R 37 , Rudolf Schleicher , had the idea of charging the boxer engine with a compressor . But only after his departure from BMW did the racing mechanic Josef Hopf , closest confidante of Rudolf Schleicher, and the BMW works driver and German champion from 1926 and 1927, Ernst Jakob Henne, implement the concept. The first engines were put to the test in 1928. The WR 750 was used for record drives by Ernst Henne, the smaller version, the WR 500, was only used for national races, as this could not break the dominance of the English brands in international racing. Only the successor model, the BMW 500 Kompressor, was internationally competitive.
Record runs
Ernst Jakob Henne set the first official world speed record for BMW on a WR 750 on September 19, 1929 with 216.75 km / h over the mile with a flying start; the power is said to have been at 75 hp (with a boost pressure of 1.2 bar). The record runs with the pushrod supercharged engine, the performance of which was increased over time, took place until September 27, 1935. Ernst Henne set 55 of his 76 world records on the WR 750 Kompressor. These rides were commercially marketed by BMW.
- List of the absolute world speed records for motorcycles (Henne / WR 750):
| date | speed | place |
|---|---|---|
| September 19, 1929 | 216.75 km / h | Munich |
| September 20, 1930 | 221.54 km / h | Munich |
| November 3, 1932 | 244.40 km / h | Did |
| October 28, 1934 | 246.069 km / h | Gyón |
| September 27, 1935 | 254.046 km / h | Frankfurt am Main |
technology
The design of the "works racing motorcycles" WR 500 and WR 750 was derived from the R 37 . The engine was designed as a longitudinally installed two-cylinder boxer four-stroke engine with overhead valves. The compressor was arranged above the gear housing and, in the first version, was driven by an additional open shaft in parallel next to the magneto and a bevel gear reducer. The compressor shaft thus ran across the direction of travel. The tank was shortened compared to the production motorcycles to make room for the compressor. The single carburetor was located behind the compressor.
From 1930 there was also a variant with a chain-driven compressor: The chain ran in the heavily modified engine housing behind the cylinders and drove the compressor shaft in the direction of travel. The WR 750 had a manual gearbox with shaft drive on the right side of the unsprung rear wheel. The front fork consisted of a leaf spring fork with a drawn short swing arm . On Ernst Henne's record-breaking machine with its semi-fairing, no brake was installed on the front wheel.
literature
- Andy Schwietzer: two-wheeled BMW WR 750 vacuum cleaner . In: OLDTIMER MARKT magazine . No. 10 , 2011, ISSN 0939-9704 , p. 30-37 .
Web links
- BMW 750 cc ohv supercharged racing machine (WR750). In: BMW history. BMW AG, accessed on September 23, 2017 (dossier of the BMW Group Archives).
Individual evidence
- ↑ a b 100 years of Ernst Jakob Henne. (PDF; 2.9 MB) BMW Veteranen-Club Österreich, 2003, accessed on August 5, 2014 (p. 29 ff.).
- ^ Karl Gall in a BMW WR 500 with supercharger at the Avus race in 1935. In: BMW History. BMW AG, 1935, accessed on July 24, 2016 ( Ragnar Sunnqvist drove Husqvarna ): "Although the BMW is the fastest German motorcycle, Sunquist wins the Avus race, Gall comes second."
- ^ Poster ( Memento of October 24, 2014 in the Internet Archive ), Poster , Poster ( Memento of October 24, 2014 in the Internet Archive )
- ↑ 750ccm supercharged racing motorcycle. In: BMW history. BMW AG, 1930, accessed on July 24, 2016 (photo in the BMW Group Archive): "First version with a transversely installed Zoller fan, driven by bevel gears"
- ↑ Chain-driven compressor. (No longer available online.) In: BMW History. BMW AG, formerly in the original ; accessed on October 21, 2014 (search in the BMW Group archive). ( Page no longer available , search in web archives )
- ↑ 750 cc - Ernst Henne's world record machine from 1935. In: BMW History. BMW AG, accessed on July 24, 2016 (photo in the BMW Group Archive).
- ↑ BMW WR 750
| 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 | ||||||||||||||||||||||||
