Title: Shock sub

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Abstract: A novel shock sub is disclosed for use in a drill string for absorbing longitudinal and impact loads. A tubular housing is provided for connection to one part of a drill string and a tubular mandrel extends into the housing for longitudinal sliding movement with an outer end portion for connection to the other part of the drill string. The mandrel and housing define an annular cavity when assembled. The mandrel has two slots, positioned 90° apart circumferentially extending for length of the annular cavity. Annular spring washers positioned in the annular cavity are of a size having a sliding fit on the outside of the mandrel and inside the housing. The spring washers are each corrugated in a wave configuration and with a tab of a size fitting one of the mandrel slots and are placed on the mandrel with alternate ones having tabs fitting in one of the slots and the others having their tabs fitting another mandrel slot. This prevents nesting of the washers and provides a greater spring efficiency in absorbing longitudinal shock. An arrangement of slots and bearings interconnects the mandrel and housing to permit sliding movement and transmit rotary motion while absorbing longitudinal shocks.


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