The shaft is the main part of the transmission torque. The axial diameter is determined by strength, stiffness and critical speed. The stiffness and critical speed of the small and medium pump are determined by the horizontal axis, the impeller slip is attached to the shaft, and the impeller distance is positioned on the axle. The modern large pump adopts the step axis, and the impeller with unequal pore diameter is mounted on the shaft and USES the involute spline to replace the short key. In this way, there is no gap between the impeller and the shaft, which does not cause the interaxial water and scour, but it is difficult to disassemble.

Bearings generally include two forms: rolling bearings and sliding bearings.

Sliding bearing oil lubrication. A lubricating system consists of a reservoir and an oil ring, which forms an oil layer on the axis when the axis is rotated to make oil and oil layers not in direct contact. Another system is to use 㓎 packing bag, filled with oil lubrication. High power pumps usually use special oil pumps to deliver oil to the bearings.

Rolling bearings are usually lubricated with cold oil, and some motor bearings are sealed and cannot be lubricated. Rolling bearings are usually used in small pumps. Larger pumps may have both sliding bearings and rolling bearings. The sliding bearing is recommended for low noise due to large pump