BMW R 47

BMW
BMW R 47, sports model
R 47
Manufacturer	BMW motorcycle
Sales description	BMW R 47
Production period	1926 to 1928
class	motorcycle
design type	Sports Tourer
Motor data
Displacement  (cm³)	494
Power  (kW / PS )	13/18 at 4000 min -1
Top speed (  km / h)	110
drive	Cardan drive
Empty weight  (kg)	126-130
Previous model	BMW R 37
successor	BMW R 57

BMW R 47

The BMW R 47 is a motorcycle with a two-cylinder boxer engine. It is the successor to the R 37 sports model with improved details and appeared in 1926.

history

development

From January 1926, BMW produced the R 47 as the successor to the R 37 that had been in production for almost two years . The R 42 , which was presented and built at the same time, was the simpler touring model with a side valve engine in the same frame.

BMW continued the modular principle with this motorcycle. The chassis and gearbox with the basic engine were largely identical; Sports and touring models differed in their cylinder heads and cylinders - sports models had hanging valves , and touring models had upright valves.

marketing

The price for the motorcycle was 1850 Reichsmarks in 1926 - 1050 Reichsmarks less than the R 37 ; Lights, horn, speedometer and pillion seat were not included.

Production ended in 1928 after 1720 units; The successor was the R 57 , which was produced from July 1928 .

technology

Compared to the R 37, the motorcycle was 2 HP more powerful and a little lighter. The successful construction principle of the R 32 otherwise remained the same:

1. Boxer engine installed lengthways, i.e. the crankshaft is lengthways and the cylinder is perpendicular to the direction of travel. This cools them well because they are not in the slipstream of the front wheel.
2. Drive of the rear wheel with cardan shaft ,
3. Frame with straight connection between steering head and rear axle.

engine

The engine with the designation M 51 was a two-cylinder boxer four-stroke engine with OHV valve control . For the first time, the engine had a slight noise reduction . The previous models released the exhaust gases essentially undamped into the open.

landing gear

The chassis is the same as that of the R 32: a tubular frame without rear wheel suspension, on the front fork is a drawn short swing arm with a leaf spring.

Technical specifications

Engine of the BMW R 47

Parameter	BMW R 47
drilling	68 mm
Hub	68 mm
Displacement	494 cc
power	18  hp (13  kW ) at 4000 min -1
Top speed	110 km / h
Empty weight	126-130 kg
Tank capacity	14 l

See also

• List of BMW motorcycles

literature

• 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 47  - collection of pictures, videos and audio files

• BMW R 47. In: BMW History. BMW AG, accessed on January 1, 2020 (dossier of the BMW Group Archives). 
• Spare parts list and tables for the BMW two-cylinder sports motorcycle type R 47. In: BMW history. BMW AG, February 1927, accessed on December 13, 2015 (spare parts list with pictures, 65 pages). 

Individual evidence

1. ↑ Price list No. 35 for BMW motorcycles: R 42, R 47. In: BMW history. BMW AG, 1926, accessed on January 4, 2016 (document in the BMW Group Archive).  
2. ↑ Josef Stelzer with a wreath on the BMW R 47. In: BMW history. BMW AG, 1927, accessed on December 12, 2015 (photo in the BMW Group Archive).  
3. ↑ Manual for BMW wheels Type R 47. In: BMW History. BMW AG, June 1927, accessed on January 4, 2016 (manual with pictures, 41 pages).