Motor includes small fan adequate for high speed cooling, with larger fan on separate shaft which can be de-coupled from motor at higher speeds

摘要

A smaller fan (12) is fixed to the motor shaft (10). This is sufficient for motor cooling at higher speeds. Further along the motor shaft there is an additional shaft (14). This can be coupled to the motor shaft, and slides axially. A larger fan (16) is connected to it. It is driven by the motor shaft and de-coupled from it above a given motor speed. A simple, axial spring-loading (20) arrangement provides a form of automatic de-clutching for the larger fan at higher speeds.