Abstract: An oil field jar includes a barrel and mandrel selectively interconnected by a ball transfer mechanism so that pulling upwardly on the jar causes a ring spring assembly to be stressed. As the spring assembly reaches its limit of stroke, the ball transfer mechanism trips so that the mandrel moves relatively freely with respect to the barrel. A hammer and an anvil carried by the mandrel and barrel then impact to create an upwardly directed jar on the fish to which the tool of this invention is connected. The ball transfer mechanism includes a plurality of balls which move both axially and radially of the tool during operation.

Abstract: There is disclosed a shock sub for incorporation in the lower part of a drill string for damping oscillations of the bit and drill string during drilling. The shock sub incorporates a spring assembly including a multiplicity of substantially annular ring springs that exhibit a spring rate of less than about 25,000 pounds per inch of deflection. This is a continuation of application Ser. No. 849,718, filed Nov. 8, 1977 now abandoned.