The Hydra-Jar AP double-acting hydraulic drilling jar is used to amplify the force applied at surface in order to free stuck drillstem components during drilling and fishing operations. The direction of jarring can be both up and down. The jar uses a unique temperature-compensation process to provide consistent impact, blow after blow, and high-temperature seals that make it suitable for hostile drilling conditions. The super seals can hold extreme pressures and the internal chamber is full pressure compensated.