5.4   Moving blade root attachments


The last-stage blades of large turbines develop centrifugal forces of hundreds of tonnes when running, very efficient methods of attachment are therefore needed.

Systems in use at present include rhombus fixings in a peripheral slot, finger-shaped pinned fixing and straight or curved fir-tree roots. Fir-tree roots provide an excellent method of attachment, since they permit very close staggering of the blade cascade and the centrifugal force is produced in an optimum manner in the shaft teeth.

      5.4.1  Fir-tree roots

      5.4.2  Pinned roots


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