The piston ring K 43570 is an essential sealing and guiding component designed for the piston K 43556 within the automatic starting-air stop valve of the Adriadiesel/Jugoturbina/Zgoda/Sulzer ZV40/48 engine. Its primary function is to maintain an effective seal between the piston and the corresponding cylinder bore, limiting internal compressed-air leakage while allowing the piston to move smoothly and reliably during pneumatic actuation of the valve. By maintaining the necessary pressure difference across the piston, the K 43570 piston ring helps ensure that pneumatic forces are transmitted effectively and that the automatic starting-air stop valve responds consistently to the engine's starting commands. The ring's dimensional accuracy, material properties, surface condition, elasticity, and compatibility with the piston groove and cylinder bore are particularly important because excessive wear, incorrect clearances, deformation, or damage can lead to pressure losses, increased friction, sticking, or delayed valve movement. During operation, the K 43570 piston ring is exposed to repeated pressure cycles, sliding contact, vibration, temperature variations, and extended periods of standby readiness, requiring dependable wear resistance and stable sealing performance. During maintenance or overhaul, the piston ring should be inspected for wear, cracking, deformation, corrosion, loss of elasticity, and surface damage, while the piston groove and corresponding cylinder surface should also be checked for scoring, deposits, or dimensional deterioration. By providing effective internal sealing and supporting smooth piston movement, the K 43570 piston ring contributes to efficient pneumatic actuation, reduced compressed-air leakage, reliable operation of the automatic starting-air stop valve, and dependable long-term starting performance of the ZV40/48 engine.