Hydraulic clamp bushing (13, 14) having a double walled sleeve (7), a hydraulic pressure medium which is trapped in a chamber (5) between the sleeve walls, and a mechanism for pressurizing the pressure medium. One, or both, sleeve walls (7) is/are formed for expanding radially outwards and/or inwards...http://www.google.com.tw/patents/US5855446?utm_source=gb-gplus-share專利 US5855446 - Hydraulic clamp bushing having sigma shaped bushing ends
