The retaining ring K 43592 is an important mechanical securing component designed for the screw plug K 43591 within the automatic starting-air stop valve assembly of the Adriadiesel/Jugoturbina/Zgoda/Sulzer ZV40/48 engine. Its primary function is to retain the associated screw plug in its designated position, helping prevent unintended axial displacement or loosening of the connected components during operation of the compressed-air starting system. By providing mechanical retention, the K 43592 retaining ring contributes to the stability and integrity of the valve assembly, particularly under conditions involving repeated pressure fluctuations, mechanical loading, and engine vibration. Accurate ring dimensions, suitable material strength, elasticity, and compatibility with the corresponding retaining groove are essential because incorrect installation, deformation, or excessive wear can compromise the ring's securing function and potentially affect the reliability of the associated screw plug. During service, the K 43592 retaining ring may be exposed to repeated mechanical stresses, vibration, temperature variations, and extended periods of standby readiness, requiring dependable resistance to fatigue, corrosion, and permanent deformation. During maintenance or overhaul, the retaining ring should be inspected for cracks, corrosion, distortion, loss of elasticity, damaged edges, and signs of improper seating, while the corresponding retaining groove and screw plug K 43591 should also be examined for wear or damage. Installation and replacement should follow the manufacturer's specifications to ensure correct positioning and secure retention. By maintaining the proper mechanical positioning of screw plug K 43591, the retaining ring K 43592 contributes to reliable valve assembly integrity, reduced risk of component displacement, dependable starting-air control, and long-term operational reliability of the ZV40/48 engine.