Impulse torque generator for a hydraulic power wrench

An impulse torque generator for a hydraulic torque wrench, comprising:

• a main shaft having a base end and extending in an axial direction;
• a cam that is rotatable with said main shaft and axially slidable on said main shaft, said cam having operating fluid guide holes extending axially therein between opposite sides thereof and said cam having at least one annular cam groove thereon;
• a cylinder receiving said base end of said main shaft and said cam, said cylinder forming operating fluid chambers on said opposite sides of said cam and said operating fluid guide holes extending between said operating fluid chambers, and said cylinder having at least one pin projecting from said cylinder into said at least one cam groove and a drive shaft to be connected to a drive source for driving said cylinder in a rotating manner, said cam groove being shaped such that rotation of said cylinder relative to said cam causes said pin to tend to move said cam in the axial direction;
• and
• a check valve structured and positioned to shut off circulation of operating fluid between said operating fluid chambers by selectively closing said operating fluid guide holes of said cam in dependence upon a relative rotating angle between said cam and said cylinder;
• wherein said cylinder is operable to be driven in a rotating manner with said drive shaft such that said at least one pin in said at least one cam groove tends to axially slide said cam on said main shaft by rotation of said cylinder relative to said cam and, upon said check valve shutting off circulation of operating fluid between said operating fluid chambers, such that said at least one pin engages said at least one cam groove to transmit rotational driving force from said cylinder to said cam and thus to said main shaft, thereby producing an impulse torque on said main shaft.