Intermittently rotatable down hole drilling tool, thrust bearing for use therein and method of assembly of such thrust bearing

Abstract From the Canadian patent

In a down hole drilling tool a closed valve is operatively moved downwards by pressurised drilling mud pumped 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 in one direction, and the upward movement of the valve causes turning of the torque member in the opposite direction. A drill bit mounted on the lower end of a rotor is connected …