BMW R 50
| BMW | |
|---|---|
 |
|
| R 50 | |
| Manufacturer: | BMW |
| Construction time: | 1955-1969 |
| Number of pieces: | 34,180 |
| Previous model: | BMW R 51 |
| Successor: | BMW R 50/5 |
| Technical specifications | |
| Engine : | Two-cylinder four-stroke boxer |
| Displacement : | 494 cc |
| Performance : | 19 kW at 5800 rpm |
| Gearbox : | Four-speed gearbox with dog clutch |
| Drive : | Card drive |
| Empty weight : | 195 kg |
| Top speed : | 198 km / h |
| Brakes : | Drum brakes |
| Tank capacity : | 17 l |
| Fuel consumption : | |
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The model R 50 is one of BMW in the second half of 1950 produced annual motorcycle with two-cylinder four-stroke - OHV - boxer engine . It is the basic model of a series of largely identical touring and sports motorcycles with engines of different power , which the article with the technical data presents as a whole. For the "sports equipment" R 50 S, R 69 and R 69 S see the separate article BMW R 50 S . The predecessor of the R 50 was the BMW R 51/3 model with a nominal output of 18 kW , with telescopic fork and straight travel suspension . The R 50, which was built from 1955, differs from it in that it has a full swing chassis with pushed long swing arm and rear swing arm as well as encapsulated suspension and the slightly increased engine output to 19 kW.
Design features
The double tube frame is welded from tubular steel with laterally attached ball heads for sidecar operation. The TR 500 from Steib was a suitable sidecar, but it required a special gear ratio for the cardan drive. The fenders and the tank are made of sheet steel. The rims and the full hubs are made of aluminum.
The engine block, like the gearbox and the rear axle drive, is made of cast aluminum . The engine and exhaust system are bolted directly to the frame. Only the upper attachment of the motor to the frame is made with rubber washers. The gear housing is screwed to the engine block.
engine
As in the previous model, the engine is a longitudinally installed two-cylinder four-stroke boxer engine. The cylinders are made of gray cast iron , the cylinder heads are made of aluminum. The camshaft, which is driven by a pair of gears, is located above the crankshaft. It operates the hanging valves via tappets , push rods running in chrome-plated steel tubes and rocker arms . The rocker arms and the piston pin in the upper connecting rod eye are mounted in bronze bushings . The oil pump is installed at the front below the crankshaft. It is driven as a simple gear pump (with a corresponding reduction) from the crankshaft via gear wheels. On the front crankshaft stub behind the aluminum cover sits the waterproof encapsulated direct current alternator . The charge regulator for the lead accumulator is placed under the cover of the alternator. On the rear stump of the crankshaft sits the heavy flywheel (with the ignition timing mark that can be seen in the peephole), which holds the dry single- disk clutch . The clutch is operated via a thrust bearing and a push rod running through the hollow main transmission shaft.
The slide carburetors are 24 Bing float chamber carburetors (model: 1/22/45, -46, 1/22/131 or -132) with a conical needle in the round slide. The wet air filter element sits on the gearbox. The suction filter is a steel mesh that is wetted with oil, on which the dust clings. It is used for coarse filtering of the intake air. The air filter is not changed for maintenance, but cleaned and re-wetted with oil.
drive
The R 50 has a foot-shifted four-speed gearbox with dog clutch, neutral indicator and kick starter. An additional manual gearshift lever that was often found on earlier BMW motorcycles is missing on this model. The drive train requires an angularly movable and length-tolerant torque transmission element at the transmission output due to the movable rocker. For this purpose, there is a universal joint at the transmission output and a length compensation at the input of the rear wheel transmission . As was the case with previous models, a hardy disk was not used. The cardan shaft to the rear wheel runs in the steel tube of the rear wheel swing arm , which at the end accommodates the aluminum bevel gear with spiral bevel gear teeth (90 ° deflection). The entire drive train is encapsulated to protect against dirt and moisture and is maintenance-free except for the oil change required every 12,000 km.
Wheels and braking system
The R 50 was the first two-cylinder motorcycle from BMW after the R 51/3, which had aluminum full-hub brakes and aluminum rims. The previous model, the R 51/3, still had steel half-hub brakes ("can end brakes") with steel rims that did not achieve the same deceleration values as the modern aluminum hubs with a larger braking surface.
landing gear
The chassis is a welded double tubular steel frame . It was used for the entire series from the R 50 to the R 69 S , except for detailed changes in the course of the facelift . The front wheel is guided on a pushed long arm swing arm with two spring struts and oil pressure shock absorbers, the rear wheel on a long swing arm, also sprung and dampened by two spring struts with integrated oil pressure shock absorbers. The rear spring preload can be converted to operation with a passenger in two stages. A special feature is the sidecar operating option, which has been prepared down to the last detail: The front long swing arm can be converted with a reversible threaded rod - for a short trail - for easier maneuverability in trailer operation. With two additional bolt eyes under the steering head, which allow the front shock absorbers to be adjusted, other upper pivot points with regard to the steering geometry can be used for greater ground clearance. It should be noted that the rear wheel ratio must be changed in sidecar operation, which requires the installation of a new speedometer.
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Typology
The BMW R 50 as a two-cylinder basic model stands in the great tradition of the pre-war boxer motorcycles R 5, R 6 and others. The basic concept of the drive with a longitudinal crankshaft, boxer engine and cardan drive to the rear wheel has always remained the same, but so much has changed with the R 50, especially the chassis, that this machine, its "sport" version BMW R 50 S , its larger-displacement parallel models BMW R. 60 and BMW R 69 together form a new category. From the full swing model series and since 1955, the cardan shafts of the two-cylinder BMW motorcycles run in an oil bath (until the introduction of the Paralever system).
The R 50 / R 60 series was revised in 1960 as the R 50/2 and R 60/2, with the same engines and a chassis with reinforced details.
See also the article full swing BMW .
Technical specifications
| R 50 | R 60 | R 69 | R 50/2 | R 60/2 | R 50 S | R 69 S | |
|---|---|---|---|---|---|---|---|
| design type | Touring / sports motorcycle with cardan drive | ||||||
| engine | Two-cylinder boxer, OHV four-stroke | ||||||
| construction time | 1955-1960 | 1960-1969 | |||||
| Bore (mm) | 68 | 72 | 72 | 68 | 72 | 68 | 72 |
| Stroke (mm) | 68 | 73 | 73 | 68 | 73 | 68 | 73 |
| Displacement (cm³) | 490 | 590 | 590 | 490 | 590 | 490 | 590 |
| Power (kW / PS) | 19/26 | 21/28 | 26/35 | 19/26 | 22/30 | 26/35 | 31/42 |
| V max (km / h) | 145 | 150 | 155 | 145 | 150 / with sidecar 110 | 155 | 175 |
| Empty weight | approx. 198 kg | ||||||
| total weight | 360 kg, with sidecar 600 kg | ||||||
| Tank capacity | approx. 18 l | ||||||
See also
Web links
- BMW R 50. In: BMW History. BMW AG, accessed on July 3, 2016 (dossier of the BMW Group Archives).
Individual evidence
- ↑ Handbook Motorcycles R 50, R 69. In: BMW History. BMW AG, March 1955, accessed on July 3, 2016 (document from the BMW Group Archives).
