rotatably mounted on the grip 12 for rotation about a centerline 38 the rotor 36 rotates in response to air passing through the motor 18 when the valve 34 is open the rotor 36 includes an output shaft 40 centered on the centerline 38 although the output shaft 40 may has other shapes without departing from the scope of the present in one embodiment the shaft has a generally cylindrical splined i e ridged exterior for connecting the shaft to the impact drive as illustrated in fig3 and 4 the impact drive 20 of the wrench 10 generally comprises a clutch base 50 a hammer 52 and an anvil shaft 54 as further illustrated in fig4 the base 50 includes forward and rearward bushing plates 60 62 respectfully separated by integral spacers 64 creating a space 66 between the plates for receiving the hammer 52 each of the bushing plates 60 62 includes a respective machined central opening 68 70 for receiving the shaft 54 holes 72 are provided on opposite sides of the openings 68 70 for receiving pins 74 76 that capture the hammer 52 in the space 66 formed between the plates 60 62 a portion 78 of the rearward central opening is 68 splined for receiving the splined output shaft 40 of the motor 18 thus the base 50 turns.