Ariel 599CC Model 4F Square Four 1939, Inglaterra

 

Ariel 599CC Model 4F Square Four 1939, Inglaterra

Fotografia

Designed by the legendary Edward Turner, Ariel's Square Four was first shown at Olympia in 1930. Unique at the time of its introduction, the 'Squariel', as it was swiftly dubbed, featured a single block of four cylinders and twin geared-together crankshafts with pistons phased at 180 degrees. The crankcase was split horizontally, unusually for a motorcycle engine of the period, while the vertical valves were operated by a single overhead camshaft. Although launched as a '500', the Squariel was soon enlarged to 601cc with an eye on the important sidecar market, this bigger 4F6 version being made available for the 1932 model year. Added to the range in 1937 was the totally redesigned Model 4G, with 995cc overhead-valve engine, making it an even more enticing prospect for sidecarists. Dropped after 1936, the '600' 4F reappeared for 1939, redesigned along the lines of its larger sibling. Not revived after WW2, the overhead-valve 4F is one of the rarest of 1930s Ariels.