Ariel Square Four
The Ariel Square Four is a motorcycle made by the British manufacturer Ariel with an air-cooled four-cylinder four-stroke engine and two crankshafts .
development
The engine was developed by Edward Turner and first tested in late 1929. The two crankshafts with two overhung crank pins , which are offset by 180 ° and which received the connecting rods , were installed transversely to the direction of travel and connected to one another via helical gears on the centrally arranged centrifugal masses so that they ran in opposite directions. This resulted in an arrangement of cylinders in a square from which the name was derived. From the teeth of the rear crankshaft, the power was first transferred directly to the integrated three-speed transmission. In the series, however, a separate Burman gearbox was used and an additional bearing was installed in front of the primary sprocket. The gas exchange was accomplished by parallel hanging valves that were operated by an overhead camshaft via rocker arms . The cylinder block and the cylinder head were each a cast iron piece . The gas outlet of the cylinder was on the outside of the head on both sides, the fresh gas ducts on the inside. The valve drive and the crankshaft gears were equipped with dry sump pressure lubrication with a gear pump each for pressure oil and return, the crank drive was lubricated with centrifugal oil.
Ariel 4F
The presentation of the type officially called Ariel 4F-31 with 498 cc and initially 20 hp took place in November 1930 at the Olympia Motor Show in London . In 1932 a 599 cc version with 24 hp (type Ariel 4F / 6) was added. That year, Ariel first went bankrupt. The production facility was bought by Jack Sangster , who let the production continue. In 1933 the 500 cc type was discontinued. The dry sump lubrication was replaced by a wet sump lubrication with a piston oil pump and the crankshaft gears were given straight teeth. In 1935 the engine casing was reinforced.
Ariel 4G / 4H
The production costs on the motorcycle market could not be covered by a corresponding sales price. Sangster therefore decided to develop a completely new square four engine with 1000 cm³, which should only have the cylinder arrangement in common with the output type. An OHV engine was designed. The crankshafts received separate gears on the left side of the engine for power transmission. They were conventionally guided in two outer bearings, which were mounted in a vertically split crankcase. The engine initially had 36 hp and was delivered from September 1936 with the model number Ariel 4G. In 1939 a more simply equipped Ariel 4H was added. There was also a 601 cm³ version with a reduced bore, which otherwise corresponded to the 4H.
Production continued after the Second World War. A telescopic fork replaced the previous trapezoidal fork in 1946.
Ariel Square Four Mark I.
Following the successful exports to the United States is increasing complaints were there due to overheating of the rear cylinder with prolonged exposure and in the UK by tapping the available fuels of sometimes only 70 octane due to decreased after the war octane number.
Val Page therefore redesigned the cylinder head and cylinder block from light metal in 1949 . The rocker arm housing was integrated into the cylinder head . Other changes included the fixing of the cylinder block and cylinder head and replacement of the light Magneto by a dynamo and a coil ignition . Thanks to the design measures, the weight could be reduced by 15 kg. This version was built until 1953.
Ariel Square Four Mark II
In 1952 the cylinder head was changed again. The exhaust gases now flowed through four individual manifolds to reduce the heat load on the cylinder head. Two individual rocker arm housings made it possible to conduct fresh gas more cheaply. The engine developed 40 HP, in a version with a compression increased to 7.2: 1 also 42 HP. In 1956 the model received full-hub brakes and a larger supply of lubricating oil was provided. This version was built until production was discontinued in 1958.
Ariel Square Four Mark III Royal Hunter
This variant was to replace the Mark II in 1954. The main design difference was a long arm swing arm instead of the telescopic fork. There were only prototypes.
Ariel Square Four Mark IV
The Mark IV was to replace the Mark II in 1958 and had a rear swing arm. Due to the change in business policy and the discontinuation of all motorcycles with a 4-stroke engine at Ariel, it stayed with the design.
Production numbers
| model | Manufacturing period | number of pieces |
|---|---|---|
| 4F-500 | 1931-1932 | 927 |
| 4F-600 | 1932-1940 | 2674 |
| 4G-1000 | 1936-1948 | 4288 |
| Mk I | 1949-1953 | 3922 |
| Mk II | 1953-1958 | 3828 |
| All types | 1931-1958 | 15,641 |
Technical data (Mark II 1958)
- Displacement: 998 cm³
- Bore: 65 mm
- Stroke: 75 mm
- Compression: 7.2: 1
- Power: 42 hp at 5800 rpm
- Transmission: 4-speed foot switch
- Wheelbase: 1422 mm
- Seat height: 787 mm
- Tank capacity: 23 liters
- Weight: 197 kg
swell
- English article from January 27, 2007
- Motorcycle Classic , 1/95
- Patent CH150402 from 1931
Web links
Individual evidence
- ↑ {{Web archive | text = archive link | url = http: //www.arielnorthamerica.org/sqfourhistory.htm | wayback = 20051102223857 | archiv-bot = 2018-03-30 11:44:47 InternetArchiveBot}} (link not available ) ArielNorthAmerica Ariel History (November 10, 2006)