Abstract: An improved hydraulic wrench including a one-piece housing in which one end of the housing forms internally a cylinder for hydraulically reciprocating power and the second end of the housing includes an opening in which a torque arm/ratchet mechanism can be pivotally connected by, for example, a square shaft. There is further included a piston shaft which has a fixed piston on the first end and the second end includes an elongated slot which provides a flat wall at 90 degrees of the reciprocating power source. The wall in the elongated slot allows the drive pin which connects the ratchet mechanism to the piston shaft to roll up and down during cycling of the tool, and provides a non-pivoting reciprocating power source as the piston shaft moves backward and forward during operation. There is included a ratchet wheel fixed to a square shaft for rotation therewith, a ratchet pawl on the drive lever and engaging the ratchet wheel to rotate the square shaft upon reciprocation of the piston shaft in the cylinder.