 Tank car manufacturing is a significant part of its business, products which are sold through its subsidiaries Union Tank Car Company in the United States and Procor in Canada.Berkshire Hathaway, which owns the largest freight railroad carrier in North America, BNSF Railway, acquired controlling interest in Marmon in 2007 and became sole owner six years later.In 1953, Jay Pritzker and Robert Pritzker acquired Colson Corporation, a struggling manufacturer of casters, bicycles, navy rockets, and wheelchairs with sales of $3 million.