Patent ID: 8650990

Claim:
A hand-operated hydraulic wrench for high torque tightening and loosening, comprising: a main casing ( 1 ); a manual drive lever ( 52 ) coupled to the casing ( 1 ), the lever is hollow and acts as hydraulic fluid accumulator ( 65 ) and contains a spring ( 53 ); a power piston ( 42 ) within the casing; wherein in order to make the power piston ( 42 ) advance forwards, it is pumped through the drive lever ( 52 ), which forces the hydraulic fluid to be displaced into a two-speed piston ( 20 ); a support ( 60 ) of the drive lever ( 52 ) which is coupled to the main casing ( 1 ) by an axis ( 59 ) and to the two-speed piston ( 20 ) through a spherical, two-head connecting rod ( 22 ); a piston sleeve ( 79 ), having two diameters for actuating the two-speed piston ( 20 ); a piston portion of greater diameter for low-pressure, fast forward movement, and a piston portion of lower diameter for high-pressure, slow forward movements; the manual lever ( 52 ) drive causes the hydraulic fluid from the accumulator ( 65 ) to flow to the lower chamber of lower diameter of the sleeve ( 79 ) and from this place the hydraulic fluid passes into a high-pressure chamber ( 49 ) driving the piston ( 42 ); and wherein in order to make the backward movement of the power piston ( 42 ) a rotation of the drive lever ( 52 ) is applied in counterclockwise direction, which causes the casing ( 1 ) to move forward to a receiving support ( 86 ) of a bearing wrench ( 90 ), retrieving the piston ( 42 ), and causing the hydraulic fluid to be displaced to the accumulator ( 65 ).