The Aristocratic Brute – Smooth, Fast and Powerful

Legend has it that Edward Turner conceived the Square Four engine in 1928 – the essence of the concept appearing so quickly that he was required to write it down on the back of a cigarette packet. The engine was essentially a pair of 'across frame' OHC parallel twins joined by their geared central flywheels, with one four- block (or Monobloc) and one head. The idea for the engine was rejected by BSA, but adopted by Ariel. Thus it became the ‘Ariel Square Four’. The idea of mounting an inline four into a performance motorcycle historically given rise to fundamental problems: mount it longitudinally and the wheelbase was too long, transversely and the bike was too fat – both outcomes would result in poor geometry handling. So anyone attempting to deliver the qualities that only four-cylinder motors might deliver to a sports bike required a new way of thinking. Turner’s vision was to provide “a four cylinder engine small enough for use in a solo motorcycle yet producing ample power for high performance without undue compression, racing cams or big choke carburetors”. Essentially, Edward Turner’s design philosophy foreshadowed decades of modern design; he stated that he merely sought to “deliver ultimate reliability and performance with minimum attentions (maintenance requirements)”.The Square Four was first shown at Olympia in 1930. Originally an overhead-camshaft 500, the model grew to 601cc before a total redesign saw it emerge as the Model 4G, with 995cc overhead-valve, all-iron engine, in 1937. Ariel’s patented Anstey link plunger rear suspension (as depicted here) became an option in 1939 but would not be offered again until 1946 when a telescopic front fork replaced the previous girder type. With its limitless reserves of pulling power and innate smoothness, the model was a superb touring mount for the solo pilot. This exquisite example of the rare crossover model comes from the Ross Duncan collection and is undoubtedly a superior example of the superbike of the girder fork era.Brute