The shaft broke at the keyway area. Actually this is an extention shaft connected to the main via a rigid coupling and there where it broke off. Up the power train there is also a flexible grid coupling connecting to the GB output shaft.

Please pay attention to the "rebuilt" keyway and "built up" diameter with some kind of epoxy which occurred long before this failure. It is a 300 RPM shaft driving a mixer.

Any idea about a cause?

Dave

This message has been edited. Last edited by: David_G,

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No sign of fatigue failure. The epoxy layer has broken increasing the clearance.May looseness in keyway cause increased stress concentration?