Complete retrofit packages available for all RTA engines in service comprise the newly-designed upper scraper, new middle sealing and new lower scraper groups, and some modifications on the gland box housing. The upper scraper group consists of a two-piece housing with newly-designed oil scraper rings made of bronze, newly-designed gas-tight sealing rings and modified tension springs. The oil scraper rings consist of four segments conforming better to the piston rod.
Two new seal rings in three parts and adapted tension springs were introduced for the middle seal group. For the lower scraper group, all rings are of bronze, since Teflon has an inferior performance when there is an increased amount of hard particles in the oil residues coming from the piston underside. Here, the new scraper rings comprise three slotted segments for adaptability to the piston rod; they are
provided with grooves at the top to promote draining of the scraped
oil.