Tachometer for air turbine motor

A high-torque rotor for a handheld or spindle-mounted pneumatic tool, comprising:

• a drive shaft with a first end, a second end, and an outer wall, the first end including an axial bore and a first set of openings in the outer wall at a first position from the first end and a second set of openings in the outer wall at a second position from the first end, the axial bore in fluid communications with the first set of openings and the second set of openings and the second end including a collet nut assembly;
• an air turbine rotor having a first annular chamber in fluid communication with the first set of openings of the drive shaft and a second annular chamber in fluid communications with the second set of openings in the drive shaft and the air turbine rotor including a set of tangential openings for exhaust air from the air turbine rotor;
• an air turbine rotor housing with an external side wall, the air turbine rotor housing surrounds the air turbine rotor, the air turbine rotor housing has a set of passages in fluid communications with a set of openings in the external side wall that directs exhaust air from the set of tangential openings of the air turbine rotor out through the side external wall;
• a measuring module including a photodetector electrically coupled to a cable, the measuring module fastened inside the air turbine rotor housing, the cable passing through one of the set of openings in the external side wall of the air turbine rotor housing;
• and
• a transmitting module electrically coupled to the cable and positioned externally to the air turbine rotor housing, the transmitting module includes a battery and a transmitter for wirelessly transmitting measurements from the measuring module.