A radial magnetic coupling transfers rotation between an outer driver and inner follower across a stationary containment shell. Explore an ideal synchronous arrangement and convert entered mechanical power and speed to torque.
Mechanical Power–Torque Identity Calculator
Enter a mechanical power and rotational speed for the same ideal steady state. Pole pairs change the schematic magnet count only; they do not predict coupling capacity.
Equation Used
- Entered mechanical power and speed describe the same steady rotating state.
- The display assumes ideal synchronous operation, so driver and follower rotate at the same speed and ideal slip speed is zero.
- Magnetic geometry, gap, materials, temperature, containment-shell losses, startup and pull-out capacity are excluded.
The illustrated driver and follower turn at the same speed while the shell remains fixed. The torque result follows from power divided by angular speed; it does not establish the coupling's torque capacity.
Driver, containment shell and follower
Magnetic-drive pump patents describe an outer magnet ring connected to the motor on the dry side and an inner magnet ring connected to the impeller on the wet side. A stationary containment shell separates the two compartments while magnetic attraction transmits rotation across it.
The animation shows the two rings rotating together around a fixed shell. It is a topology diagram, not a magnetic-field, stress or loss simulation.
Sealless topology and exact unit conversion
Use the calculator to convert independently known mechanical power and rotational speed into torque. Use the exact coupling and pump manufacturer data for capacity, permitted speed, materials, temperature, containment pressure, startup and operating limits.
Rotational power identity
Power equals torque times angular speed. The familiar 9550 factor is the rounded unit-conversion form for kilowatts, revolutions per minute and newton-metres.
Arithmetic example
For 7.5 kW at 2,900 rpm, angular speed is 303.69 rad/s and implied torque is 24.70 N m. Under the explicitly assumed ideal synchronous state, driven speed is 2,900 rpm and slip speed is zero. This does not size the coupling.
Model boundary
Pull-out torque and losses depend on complete magnet, rotor and shell geometry, materials, temperature and speed, so they require validated manufacturer data, analysis and test.
Magnetic-coupling questions
Does zero ideal slip prove the coupling will stay synchronized?
No. It only states the selected ideal operating assumption. Capacity and transient response are not calculated.
Do pole pairs change the result?
No. That input changes only the explanatory drawing. No universal capacity law is asserted.
Can this select a gap or containment shell?
No. Those are safety-critical, design-specific decisions outside this model.
Primary and manufacturer references
- US 2010/0156220 A1, Inner drive for magnetic drive pump: describes synchronously coupled inner and outer drives separated by a containment shell.
- US Patent 5,201,642, Magnetic drive pump: documents concentric inner and outer magnet rings and a separating containment shell.
- Iwaki America MD/WMD instruction manual: manufacturer operating-principle diagram showing the field transmitted through the rear casing from drive magnet to driven magnet and impeller.
- OpenStax Physics, Rotational Motion: angular velocity, torque and rotational-power relationships.
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