Patent attributes
A power wrench has a rotation motor, and a hydraulic pulse unit. The pulse unit includes an inertia drive unit connected to the motor. The inertia drive unit includes an oil chamber with an impulse generating mechanism, and an output spindle extending into the oil chamber to receive torque impulses. The inertia drive unit has a cylindrical member defining the oil chamber, a rear end wall, and an air separator element co-rotating with the wall and having a substantially axially facing surface which together with a congruent surface on the rear end wall forms oil passages in the form of a clearance gap through which oil mixed with air is circulated between one or more oil inlet openings, past one or more air outlet openings, to one or more oil outlet openings. Air is extracted from the oil and is gathered in a centrally located air collecting chamber.
