The primary motion that drives manufacturer Electro-Motive Diesel (EMD) is locomotion. EMD designs, builds, sells, and services diesel-electric locomotives for commercial railroad applications: commuter, freight, intercity passenger, mining, and switching. It has the largest installed base of diesel-electric locomotives in the world, with products sold in more than 100 countries. EMD also supplies locomotive replacement parts and diesel power engines for marine propulsion, oil drilling rigs, and power generation. The company is a subsidiary of Caterpillar.