Valvetrain components in Cummins engines control airflow and exhaust timing. Camshafts rotate to actuate lifters and pushrods. Rocker arms transfer motion to open and close valves. Valve springs ensure valves return to their seats. Precision machining maintains timing and clearance. Hydraulic lifters reduce noise and wear. Components endure high stress and temperature cycles. Cummins engineers valvetrain for durability and precise valve timing.