The Model 1, more commonly known as Big 4, was a Norton

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

made between 1907 and 1954 in various forms. With , it was the largest and most powerful side-valve engine in the model range and with plenty of low end torque was mostly used to haul sidecars. It was called Big 4 because it was rated at 4

tax horsepower The tax horsepower or taxable horsepower was an early system by which taxation rates for automobiles were reckoned in some European countries such as the UK, Belgium, Germany, France and Italy; some US states like Illinois charged license plate ...

. Mechanically, 'the power output, about which Norton Motors tended to be cagey, was lowly, 14

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for 1951'. Approximately 4700 of the nearly 100,000 military bikes made by Norton during WW2 were Big 4 sidecar outfits. Designed to carry two or three men plus their fighting equipment over very rough terrain, the Big 4 was used for reconnaissance and carrying loads of ammunition to the front line troops.

Civilian Norton Big 4

The first Big 4 machines were civilian versions starting in 1907 with a bore and stroke of 82 x 120 mm. The model was produced for nine years after the end of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. In 1948 the stroke was reduced to 113 mm to give 596cc capacity. In 1955 Norton ended the manufacture of side-valve singles to concentrate on overhead-valve twins.

Military Norton WD Big 4

The WD Big 4 was a development of pre-war trials outfit with a sidecar wheel coupled to the motorcycle rear wheel through a dog clutch and drive shaft. Initial trials were carried out at

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Dorset Dorset ( ; Archaism, archaically: Dorsetshire , ) is a Ceremonial counties of England, ceremonial county in South West England. It is bordered by Somerset to the north-west, Wiltshire to the north and the north-east, Hampshire to the east, t ...

and it coped well with challenging terrain. The simple design also meant it was easy to maintain in the field. All three 18" X 4.00 wheels were interchangeable with various makes of tyres for off-road use. The sidecar was unarmoured, with thin sheetmetal on the front of the sidecar and there was no sprung suspension in the rear of the heavy duty frame. The sidecar was mounted on four leaf springs, and had two friction disc shock absorbers at the back. The Big Four was eventually replaced by the Ford GP or the Willys Jeep in 1941. The Big 4 could be equipped with a

Bren gun The Bren gun (Brno-Enfield) was a series of light machine guns (LMG) made by the United Kingdom in the 1930s and used in various roles until 1992. While best known for its role as the British and Commonwealth forces' primary infantry LMG in Worl ...

or a 3-inch mortar, bombs could be fitted to a platform in place of a sidecar, but this seems to have been a one-off model, same with the Thompson equipped Big 4.

References

External links

Norton Big Four restoration
{{Norton motorcycles Military motorcycles Big 4

Civilian Norton Big 4

Military Norton WD Big 4

See also

References

External links