Mechanical or hydraulic device used in the drill stem to deliver an impact load to another component of the drill stem, especially when that component is stuck.
Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards
A tool used to deliver an axial impact load to the downhole string.
Source:API SPECIFICATION 19TT, Specification for Downhole Well Test Tools and Related Equipment, First Edition, October 2016. Global Standards