The Square Four was essentially two 2-cylinder engines, each with traverse (across-the-frame) crankshafts that were geared together ... this was a cruiser. The 1948 Ariel Square Four continued to use ...

Ariel’s Square 4 – affectionately ... had come up with the concept of a square-four engine as far back as 1928 – essentially a pair of across-the-frame parallel twins – and had offered ...

The original Ariel Square Four was created by legendary engine designer ... The Model 4G ditched the rigid rear frame in 1939 in favor of an Anstey-link plunger rear suspension, and a new frame to go ...