Chuck Yung 
EASA Technical Support Specialist 

A common observation about 2­-pole machines fitted with sleeve bearings is the inherent weak magnetic centering force. The classic symptom is chronic axial movement: a 2-pole rotor drifting “to and fro” from the established magnetic center position. This article addresses the numerous causes of this phenomenon, colloqui­ally referred to as “hunting.” Although the focus is on 2-pole motors, much of this information applies to sleeve bearing motors of any speed rating. Identifying the cause of a problem is good, but solutions are a lot more useful, so I’ve included those as well. 

We can use magnets to describe how a motor works. Opposite poles attract; like poles repel. The magnetic field rotating within the stator turns the rotor, and magnetic force affects the axial position of the rotor relative to the stator core. 

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Categories: Technical topics, AC motors

Tags: Axial hunting

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