Pneumatic torque impulse tool

A pneumatic torque impulse tool, comprising a housing (10) with an impulse chamber (11) at a forward end thereof, a motor chamber (12) having a cylindrical wall (14) and disposed rearwardly of said impulse chamber (11), a vane type rotation motor (19) disposed in said motor chamber (12), an air inlet passage (26), and an air outlet passage (27), both of said air inlet and outlet passages (26, 27) communicating with a rear end of said motor (19), a hydraulic impulse generator (15) rotatively supported in said impulse chamber (11), said motor (19) including a cylinder (20) and a vane carrying rotor (21) drivingly connected to said impulse generator (15), said cylinder (20) having three or more radial air communication openings (37a,b, 38a,b, 39a,b), at least one (39a,b) of which permanently acts as an outlet opening means, wherein:

• said cylinder (20) is formed with external grooves (37c,d, 38c,d, 39c,d, 41a,b) extending from either ends of said cylinder (20) and which define together with said cylindrical wall (14) parts of said air inlet and outlet passages (26, 27),
• each one of said air communication openings (37a,b, 38a,b, 39a,b) is separately located in one of said grooves (37c,d, 38c,d, 39c,d),
• said at least one air communication opening (39a,b) permanently acting as an outlet opening means is located in one of said grooves (39c,d) extending from the forward end of said cylinder (20) and communicating with said impulse chamber (11), whereas the other ones (37a,b, 38a,b) of said air communicating openings are located in those of said grooves (37c,d, 38c,d) extending from the rear end of said cylinder (20), and
• at least one (41a,b) of said grooves extends over the entire length of said cylinder (20) without coinciding with any one of said air communication openings (37a,b, 38a,b, 39a,b), thereby connecting said impulse chamber (11) to said air outlet passage (27).