The rotary slide valve K 43173 is a precision control component within the starting device of the Adriadiesel/Jugoturbina/Zgoda/Sulzer ZV40/48 engine, where it helps regulate and sequence the distribution of the starting medium during engine start-up. Through controlled rotary movement, the valve brings its ports or control passages into the required positions, allowing the starting system to direct the starting medium according to the engine's prescribed starting sequence. Accurate angular positioning, dimensional precision, surface condition, and suitable operating clearances are particularly important because wear, sticking, contamination, or excessive leakage can disturb the distribution sequence and reduce starting reliability. During operation, the K 43173 is exposed to repeated starting cycles, pressure forces, friction, vibration, and long periods of readiness between starts, requiring dependable movement and resistance to wear and corrosion. During overhaul, its sliding and sealing surfaces, ports, clearances, and associated components should be inspected for scoring, deposits, corrosion, deformation, or excessive wear. By providing accurate and repeatable control of the starting-medium distribution, the K 43173 rotary slide valve contributes to reliable engine starting, correct sequencing of the starting system, reduced mechanical stress, and dependable operational readiness of the ZV40/48 engine.