... ,250-inlet diameter (mm)A-first reconstruction, Y-centrifugal oil pump, S-first impeller double-suction,,material code of over-current ... times are represented by A, B.......Structure:AY-type oil pump has six models: single-stage single-suction cantilever type, ... (stuffing box) is combined pump cover, and includes two seals: stuffing seal and mechanical seal (balancing type, bellow type and tandem type ...