US Patent 7338426 Centrifugal separator with rotation detector

A centrifugal separator for separating dirt particles from a fluid includes a separator cylinder, which rotates in a separator housing and into which the fluid to be cleaned is introduced. A detection device for indicating the operating state of the separator cylinder is provided, which includes a radially extending guide tube in which a detection element is accommodated in such a way that the detection element can be outwardly displaced within the guide tube under the influence of centrifugal force when the separator cylinder rotates and can move between a normal position and a contamination-indicating position.