Patent ID: 8480340

Claim:
A hydraulic nut comprising: a casing ( 1 ); two blind holes for housing two bolts ( 15 ) and two galleries ( 21 , 21 ′) which are connected each with a ball valve ( 23 , 23 ′); a shank-screw body ( 6 ), with a seal ( 2 ); a threaded clamp nut ( 4 ) having a plurality of depressions ( 11 ); two ball valve cap screws ( 13 , 13 ′) through which the hydraulic fluid is supplied; wherein upon threading the clamp nut ( 4 ) on the casing ( 1 ), it forces an axial bearing roller ( 18 ) to abut against a seal ( 2 ), which apart from being a moisturetight seal, it performs the function of piston head, and as the clamp nut ( 4 ) threading continues, the hydraulic fluid contained in a chamber ( 17 ) is displaced into a chamber ( 17 ′), which is of greater diameter, whereby the hydraulic fluid forces the shank-screw body ( 6 ) to be displaced upwards, thus stretching.