Shafts for liquid ring vacuum pumps

What it does inside the pump

The shaft carries the impeller between the two bearings and transmits the full torque. On most frames it is a stepped shaft with the impeller seated on a keyed fit, a sleeve area under the seal or packing, and bearing journals at each end.

How it fails, and what you see first

Shafts are a long-life item and rarely wear out in service. They are replaced for three reasons: fretting damage at the impeller fit after the pump has been run with a loose impeller, corrosion pitting under the sleeve where seal liquid has sat, and bending. A bent shaft is almost always the result of coupling misalignment or of a hydraulic slug — starting a pump with liquid standing in the casing. Check runout before you reuse one.

What to send us so the part is right

Model, serial, and total length plus each diameter step with its length, measured from the drive end. Keyway width and depth, and thread details at the impeller end if there is a retaining nut. State the material you need: C45 steel for clean water duty, 304/316 or duplex where the seal liquid is corrosive.

Which models take this part (273)

Grouped by pump family. Model numbers in blue have their own page with the full specification table; the rest are supplied from the same frame — send the model and we confirm against the drawing.

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