Made by pre-War Germany's premier toy manufacturer around 1909, the 3ft 2in (96cm) long Fidelitas features seated clowns with a variety of props - a hoop, a bouquet of flowers, and the curious sign that gives the toy its name.
Kaufman, aged 78, has been collecting toys for 50 years, although many of his higher profile acquisitions were made following the sale of his stake in the family business Kay-Bee Toys in 1981. His Märklin clown caravan had been bought at Bertoia a decade ago for $30,000.
It has some replaced elements - including a leg, a hand and the sign carried by the figure at the rear of the train - but ranks among less than ten complete examples known (the individual carriages were also sold separately by Märklin and survive in greater numbers).
Estimated at $30,000-40,000, it sold to a European collector at $90,000 (£66,200) plus 15 per cent buyer's premium.
One blogger described the Kaufman collection - which could provide Bertoia with as many as five sales - as "a procession of toys worthy of a ticker-tape parade". With many strong prices posted for early German, French and American 'connoisseur' toys, Part I brought a total of $4.2m (£3.1m).
By Roland Arkell
