Abstract: A pneumatically powered torque impulse delivering tool for screw joint tightening comprises a housing (10) with a forward impulse chamber (11) enclosing a hydraulic impulse generator (15), a motor chamber (12) disposed rearwardly of the impulse chamber (11) and including a vane type air motor (19), and air inlet and outlet passages (26, 27) located at the rear end of the housing (10). The motor cylinder (20) is provided with radial air communication openings (37a,b, 38a,b, 39a,b) and outer grooves (37c,d, 38c,d, 39c,d) forming passages for connecting the openings (37a,b, 38a,b, 39a,b) to the air inlet and outlet passages (26, 27).