TecnoVeritas developed for American Presidential Lines – APL, a system to monitor the wear condition of the main engine liners of its then 160 container ships. The system is known as “Liner Guardian” was intended to detect the thickness of the lubricating oil film, and gave rise to a European patent. The system is based on the signals obtained from the oil thickness of the liners when the piston rings pass each time. The sensors were also developed by TecnoVeritas and are based on the Eddy effect, complemented by two other sensors, the pressure sensor, which continuously reads the pressure inside each cylinder, and an encoder that reads the angular position of the piston. The software and hardware were all produced by TecnoVeritas, as well as their respective commissioning.