Hydraulic torque impulse mechanism

Hydraulic torque impulse mechanism, comprising a rotatively driven drive member (10) provided with a concentric fluid chamber (12) as well as a radially acting cam means (25,26,28), an output shaft (16) extending through said drive member fluid chamber (12) and having two radially extending cylinder bores (18,19) which communicate continuously with each other via a central high pressure chamber (23), and two oppositely disposed piston elements (20,21) which are reciprocable in said cylinder bores (18,19) by said cam means (25,26,28),

• characterized in that said output shaft (16) comprises at least one valve chamber (45,46) which communicates continuously with said high pressure chamber (23), said at least one valve chamber (45,46) comprises one or more fluid communicating openings (50) for connecting said high pressure chamber (23) to said drive member fluid chamber (12), and a pressure responsive valve means (51) arranged to block said one or more fluid communicating openings (50) as the pressure difference between said high pressure chamber (23) and said drive member fluid chamber (12) exceeds a certain level.