A clutch release bearing comprising a fixed portion (5, 6) including an outer body (5) and an inner support tube (6) concentric therewith and separated therefrom, and defining an axially extending blind ring-shaped cavity (50) capable of being supplied with a fluid and housing an axially movable tubular...http://www.google.com/patents/US5865288?utm_source=gb-gplus-sharePatent US5865288 - Hydraulically controlled clutch release bearing for a motor-vehicle diaphragm clutch
