Caterpillar Inc. says it is seeking to buy a Chinese maker of mining machinery for as much as $886 million. Hong Kong-based ERA Mining Machinery Ltd. designs, builds, sells and supports equipment for underground coal mining in  China. CAT officials say  expanding in the mining industry is one of its top priorities. The deal needs the approval of China's Ministry of Commerce and other regulators.  This summer, U.S. mining equipment maker Joy Global Inc. said it wants to take majority control of China's International Mining Machinery Holdings Ltd. That deal still needs government approval.