Hubert & Wösner M
1 model in this series
Hubert & Wösner M 3-12: air-cooled single-cylinder diesel engine with 660 cc displacement, 12 hp at 2,000 rpm and a top speed of 20 km/h as a compact small tractor
The M 3-12 belongs to the class of small single-cylinder tractors built during the 1950s for smallholdings, steep terrain and fruit and vine growing. Machines of this kind widely replaced draught animals on small plots at a time when larger, multi-cylinder tractors were too heavy or too expensive.
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The air-cooled single-cylinder diesel engine of 660 cc delivers 12 hp at 2,000 rpm. The design top speed is 20 km/h, unladen weight is 800 kilograms and the wheelbase is 1,550 millimetres — figures typical of a compact, agile small tractor with a short turning circle.
With a design top speed of 20 km/h, the machine falls into the lower part of driving licence class T, which in Germany covers vehicles up to 60 km/h. Air cooling made single-cylinder engines of this kind lower-maintenance and more frost-resistant than water-cooled units, but required clean cooling fins to prevent overheating.
When buying such an old single-cylinder machine, the condition of the cylinder's cooling fins is the first thing to check, as they must be free of oil and caked dirt. Compression, the injection pump and bearing clearance on the crankshaft deserve equal attention, along with corrosion on the steering knuckles and linkage, which is often the real weak point on small tractors of this age. The clutch lining and the play in the steering gear are worth a look as well, since replacement parts for a machine this old and this rare are not always readily available.
Sources: SpecCodex-Register: Kennwerte des Modells M 3-12
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Tractor in 3D section
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