Cummins is the top manufacturer of diesel engines used in commercial trucks, off-highway equipment, and railroad locomotives, in addition to standby and prime power generators. The company also sells powertrain components, which include filtration products, transmissions, turbochargers, aftertreatment systems, and fuel systems. Cummins is in the unique position of competing with its primary customers, heavy-duty truck manufacturers, who make and aggressively market their own engines. Despite robust competition across all its segments and increasing government regulation of diesel emissions, Cummins has maintained its leadership position in the industry.