shell as it is moved translationally by the application by pumps 33 33a or withdrawal of hydraulic fluid to shoes 22 24 this also permits the radially extensible change in shape of the barrier chambers 82 84 while maintaining the chambers sealed thus pressurized cooling liquid is supplied to the first chamber 82 via conduit 100 which is axially outside of second chamber 84 flows through chamber 82 out into annular space 68 inwardly into chamber 84 and out of the roll via conduit 104 the cooling liquid thus is brought into direct engagement with the inner surface 39 of spacer 38 to cool spacer 38 or to cool the inner surface of the end of shell 18 if a spacer is not utilized this inward flow of cooling liquid 103 within both annular space 68 and chambers 82 84 in conjunction with rotary seals 69 69a and the cooperating flanges in chambers 82 84 effectively seals the hot hydraulic fluid 28 from physical contact with the bearings in addition the cooling zone which extends substantially between rotary seals 69 69a or the axial length of inner and outer spool members 74 78 effectively shields the bearings from radiant heat from the hot hydraulic fluid and minimizes the conduction of heat through the barrier components themselves due to their relatively thin construction and intimate contact with cooling liquid thus a heat shield between the hot hydraulic.