Thyssenkrupp's foundation, the company's largest shareholder, pledged to work with unions and management to appoint a successor to its chairman Ulrich Lehner. : FRANKFURT, July 17 (Reuters) - Thyssenkrupp’s foundation, the company’s largest shareholder, pledged to work with unions and management to appoint a successor to its chairman Ulrich Lehner. Thyssenkrupp has been gradually dismantling its complex submarines-to-elevators business and last month merged its European steel assets with those of rival Tata, further retreating from a core business.