As regards performance unit R-500 can be considered identical with unit R-400, with the advantageously bigger working range thanks to the longer arms. The machine consists basically of the following elements: radial arm, lockable elbow joint, tilting arm and head. The compressed-air motor is coupled to the latter. Through the foot and by means of three M8 screws the machine can be fixed to a table or workbench. Such attachment can also be obtained by means of a simple clamp. The radial arm and the tilting arm revolve about themselves. The latter tilts therewith always maintaining the perpendicularity to the foot reference plane.The machine incorporates an air servicing unit (filter + regulator + lubricator) for the correct operation of the motor. The modular system consisting in a series of 7 quick-change modules (reducers) is provided for coupling to said motor. As a result of this 7 output speeds (90, 170, 300, 550, 750, 1050, 2100 rpm) are available thus allowing to adapt the tap speed to every type of thread. The handle allows to balance the tilting arm and to position it at the operator's convenience. The modular system admits the quick-change tap holders with or without safety clutch depending on the intended job (blind or through holes). Threading capacity from M2 up to M24 (M27).