Hydraulic turbo machines including pumps and pump turbines having pivotally adjustable wicket gates are vulnerable to damage caused by the ingress of dirty water containing abrasive particles into the bushings in which the stems of the wicket gates are pivotally supported in the headcover and bottom ring. This problem is overcome by the provision of individual seals between the end of each wicket gate and an adjoining surface portion of the headcover or bottom ring in which the bushings are located. In addition, seal water at a pressure in excess of machine operating pressure forces the seal ring into contact with the end of the wicket gate and also causes a slight flow of clean water outwardly between the seal and the respective end of the wicket gate, so as to keep the seal entry zone flushed clear of particulate material.
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