A canned motor pump combines the hydraulic section and electric motor into one compact, seal-less unit. Understanding the main components is useful for pump selection, troubleshooting and spare-parts planning because many internal parts also depend on the pumped liquid for lubrication and cooling.
Pump Casing and Impeller
The casing guides the liquid through the pump and contains the pressure generated by the impeller. The impeller converts rotational energy into flow and head. Single-stage and multistage arrangements are available depending on the required hydraulic duty.
For replacement work, impeller diameter, width, vane geometry and installation dimensions should be checked against the original pump rather than selected from model name alone.
Rotor and Stator
The rotor is connected directly to the pump shaft and impeller, so no external coupling is required. The stator generates the magnetic field that drives the rotor. This integrated arrangement keeps the unit compact and avoids coupling alignment work.
The stator winding is isolated from the process liquid by a thin stator liner. The rotor itself is protected by a rotor liner. Liner materials such as SUS304L, SUS316L or HC-276 may be considered according to corrosion, temperature and mechanical requirements.
Bearings, Shaft Sleeves and Thrust Parts
Canned motor pumps normally use fluid-lubricated bearings. Depending on the application, bearing materials may include graphite, antimony carbon or SSiC. Shaft sleeves provide the running surface in the bearing area, while thrust disks and thrust collars control axial position and carry axial loads.
- Bearings: support radial rotation
- Shaft sleeves: protect the shaft running surface
- Thrust disk / collar: control axial movement
- Wear-resistant surfaces: tungsten carbide or Stellite may be used where suitable
Replacement dimensions and running clearances should be confirmed carefully. See our Canned Motor Pump Spare Parts section for typical components.
Internal Liquid Circulation
In many canned motor pump designs, part of the process liquid circulates through the motor cavity. This internal flow lubricates the bearings and removes heat from the motor section before returning to the pump circuit.
The circulation path is not identical for every application. High-temperature, slurry, reverse-circulation and multistage pumps use different arrangements to suit fluid properties and operating conditions. For volatile or low-temperature liquids, vapor formation and suction conditions must also be considered.
Why Component Matching Matters in Replacement Projects
A replacement bearing, sleeve, thrust component, liner or rotor assembly must match more than the visible dimensions. Material, clearances, surface treatment, hydraulic duty and the original circulation design all affect reliability.
For many TEIKOKU, NIKKISO and HERMETIC applications, YUEMAX can review the original model, drawings, samples and service conditions before confirming a replacement solution.
Send your model, drawings or spare-parts dimensions for review →