Product Overview This swing reduction gearbox, available under part numbers 451-2798, 378-9557, and 451-2801, is the swing transmission unit specially designed for the E390F excavator swing system. It reduces the output speed of the swing motor and increases torque to drive the upper structure to rotate. Built with a planetary gear structure, wear-resistant alloy gears, and precision machining, it offers direct replacement installation and stable torque output performance for