Caterpillar is a company that manufactures construction and mining equipment, diesel and natural gas engines, industrial gas turbines, and diesel-electric locomotives.
Cummins is a company that designs, manufactures, sells, and services diesel and natural gas engines and powertrain-related component products, including filtration, aftertreatment, turbochargers, fuel systems, controls systems, air handling systems, transmissions, electric power generation systems, batteries, and electrified power systems.
Tenneco is a company that designs, manufactures, markets, and sells products and services for light vehicle, commercial truck, off-highway, industrial, and aftermarket customers.
Aerojet Rocketdyne Holdings (formerly known as GenCorp) is an aerospace and defense company providing propulsion and energetics to space, missile defense, strategic systems, tactical missile, and armaments customers.