Drilling tool changer apparatus

An apparatus for changing a drilling tool for a drilling rig, where the drilling rig comprises a drill tower supporting a drill pipe;

• the apparatus for changing a drilling tool comprising:
• a drilling tool changer assembly moveable between a storage position and an exchange position;
• the drilling tool changer assembly supporting a rotatable carousel assembly;
• the rotatable carousel assembly capable of removal from the drilling tool changer assembly and capable of replacement on the drilling tool changer assembly in a same angular position;
• the rotatable carousel assembly having a plurality of bit adaptors for holding drilling tools;
• and
• the rotatable carousel assembly selectively rotatable to bring a selected drilling tool into coaxial alignment with the drill pipe when the drilling tool changer assembly supporting the rotatable carousel assembly is moved into the exchange position;
• wherein the drilling tool changer assembly further comprises a detector for detecting the presence or absence of a drilling tool in a bit adaptor of the plurality of bit adaptors that is in a predetermined angular position for pick-up or drop-off of a drilling tool in the rotatable carousel assembly.