BMW R 3

BMW R 3 in Wolfegg

The BMW R 3 was a touring motorcycle with 300 cm³ from the German motorcycle manufacturer BMW , which was only built in 1936.

history

Four years after the introduction of the large single-cylinder R 4 motorcycle , BMW presented the R 3 in February 1936 at the German Motor Show in Berlin. Only one series of the R 3 was built. The introduction price was RM 1,050; in September 1936 the price had already been reduced to RM 995.

With a displacement of 300 cm³, it was placed unfavorably on the market because it neither had the performance of the R 4 nor had the advantage of driving license and tax exemptions that made the R 2 attractive. With only 740 copies made in the single year of production, it fell short of expectations. The R 3 and R 4 models were replaced by the R 35 as early as 1937 .

Design features

Motor, gearbox and cardan drive

The R 3 is characterized by a larger displacement than the R 2 and also by great robustness. Technically, however, the R 3 is more closely related to the last two series 4 and 5 of the BMW R 4 .

engine

The bumper motor has overhead valves ( OHV design ). The on-board voltage network is fed by a 6 V / 45 W direct current generator located on the top left of the engine block. A battery is located to the left behind the engine to store electricity. The ignition is a so-called battery ignition. It is controlled by a camshaft operated breaker located in front of the engine in a cylindrical can.

drive

The R 3 had a manual four-speed gearbox with a drive shaft 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.

The gear housing was flanged directly to the motor housing. The input shaft was driven directly by the single-plate dry clutch in the crankshaft's flywheel. The output shaft drove the drive shaft via a hardy disk in direct extension.

The kick starter was arranged on the right side - a sidecar operation was not planned.

landing gear

This motorcycle appeared in the then common BMW design, with a pressed and riveted sheet steel frame without rear suspension and the drawn short oscillating fork with leaf suspension for guiding the front wheel. The front and rear brakes are designed as half-hub brakes in accordance with the state of the art at the time.

Technical specifications

Parameter	Data of the R 3
drilling	68 mm
Hub	84 mm
Displacement	305 cc
power	11  PS (8  kW ) at 4200 min -1
Top speed	100 km / h
Empty weight	149 kg
total weight	349 kg
Tank capacity	12 L

See also

• List of BMW motorcycles

literature

• Erwin Tragatsch: All Motorcycles 1894 - 1981 . Motorbuch Verlag, Stuttgart 1997, ISBN 3-87943-410-7 .
• Udo Stünkel: BMW motorcycles typology: All series models from 1923 . Delius Klasing, Bielefeld 2008, ISBN 978-3-7688-2451-4 .

Web links

Commons : BMW R 3  - collection of images, videos and audio files

• BMW R 3. In: BMW History. BMW AG, accessed on December 14, 2018 (dossier from the BMW Group Archives). 
• Spare parts list for the BMW R 2/200 ccm, R 3/300 ccm, R 4/400 ccm motorcycles. In: BMW history. BMW AG, May 1942, accessed on December 14, 2018 (spare parts list for all series with pictures, 99 pages). 

Individual evidence

1. ↑ BMW presents the R 3. In: BMW History. BMW AG, February 15, 1936, accessed on December 14, 2018 (document in the BMW Group Archive). 
2. ↑ Price list No. 58. In: BMW History. BMW AG, February 1, 1936, accessed on December 14, 2018 (document in the BMW Group Archive). 
3. ↑ Price list No. 60. In: BMW History. BMW AG, September 1, 1936, accessed on December 14, 2018 (document in the BMW Group Archive). 
4. ↑ BMW R 3. In: BMW History. BMW AG, accessed on December 14, 2018 (dossier of the BMW Group Archive): "With only 740 units manufactured in the first year, the R 3 remained far below expectations, so that the R 3 was already upgraded from a new single-cylinder model in 1937, the R 35 has been replaced. " 
5. ↑ BMW R 3 engine. In: BMW history. BMW AG, 1936, accessed on December 14, 2018 (photo in the BMW Group Archive). 
6. ↑ ^{a b} Manual for the BMW wheels, type R 2, R 3 and R 4. (PDF) In: BMW history. BMW AG, March 1936, accessed on December 14, 2018 (manual with pictures, 71 pages).