Sperry Rand SPD (Special Products Division) which was a division of New Holland, holds an important place in ATV history. In 1967 John Plessinger was a college student working on an engineering project. He designed the world’s first 3-wheeled ATV called the TriCart. John leased the patents to Sperry Rand and began helping with mass production after his graduation. An interview with John about the Tricart can be found here.

Who Invented the 3-Wheeled ATV? – ATV Scene Magazine

Source: Wedge, Tricart, Tricub & Minicub - Mudd-Ox IncMudd-Ox Inc