Norton Big 4
Encyclopedia
The Model 1, or more commonly known as Big 4 was a Norton
motorcycle
made between 1907 and 1954 in various forms. With 633 cc, it was the largest and most powerful side valve engine, with plenty of low end torque in the model range, and was mostly used to haul sidecars. 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. It was called Big 4 due to its power rating of 4 hp, calculated as tax horsepower
. Calculated using current methods the horsepower rating would be 14 brake horsepower.
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
when Norton ended the manufacture of side valve singles to concentrate on twins. As from 1948 the bore and stroke changed to 82 x 113 mm to give 596cc capacity.
in Dorset
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 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 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
Norton (motorcycle)
Norton is a British motorcycle marque, originally from Birmingham, founded in 1898 as a manufacturer of "fittings and parts for the two-wheel trade". By 1902, they had begun manufacturing motorcycles with bought-in engines. In 1908, a Norton-built engine was added to the range...
motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
made between 1907 and 1954 in various forms. With 633 cc, it was the largest and most powerful side valve engine, with plenty of low end torque in the model range, and was mostly used to haul sidecars. 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. It was called Big 4 due to its power rating of 4 hp, calculated as tax horsepower
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 Britain, Belgium, Germany, France, and Italy; some US states like Illinois charged license plate purchase and renewal fees for passenger...
. Calculated using current methods the horsepower rating would be 14 brake horsepower.
Civilian Norton Big 4
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
when Norton ended the manufacture of side valve singles to concentrate on twins. As from 1948 the bore and stroke changed to 82 x 113 mm to give 596cc capacity.
Military Norton WD Big 4
The WD Big 4 was a development of prewar 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 StudlandStudland
Studland is a small village on the Isle of Purbeck in the English county of Dorset. It is famous for its beaches and nature reserve. In 2001 Studland had a population of 480, the lowest in 50 years...
in Dorset
Dorset
Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...
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 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 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