AIR DRILLING SYSTEM

Down hole Intermittently Rotatable Air Motor is placed above Air Hammer a nd percussive drill bit. By applying weight on the drill string Air Motor is engaged. Air Motor intermittently rotates the Air Hammer and percussive drill bit at low RPM. By lifting the drill string off bottom, thus eliminating the weight on bit Air Motor is disengaged and a free flow of the compressed air is facilitated through the Air Motor into the Air Hammer and the percussive drill bit. In the Air Motor a closed valve is operatively moved downwards by compressed air flowing down the drill string, the valve when it attains its lower position being opened and being returned under the influence of a spring or other upwardly urging means acting on the valve to its upper position at which the valve is closed thereby to complete the cycle of operations. The valve is so continuously coupled to a torque member that the downward movement of the valve causes turning of the torque member so that during the downward movement of the valve the rotor and the Air Hammer and the drill bi t are rotatably driven by the torque member but are not rotated during the upward movement of the valve. During the upward movement of the valve, the compressed air flows through the open valve and continues to energize the Air Hammer and to flowt hrough the nozzles in the drill bit. Valve is prevented from rotating by being engaged on the outside in straight longitudinal grooves while on the inside it is engaged i n angular grooves that are on the outside of the torque member. Thrust bearing is protected from the destructive shocks caused by Air Hammer by implementing hard elastomer washers.