Working principles
● Upward Jarring
Lifting the drill stem gives the hydraulic jar an upward force, moving the upper hydraulic mechanism along with it. This generates an increased pressure in the working fluid. Thus, when the jar reaches a predetermined stroke, the fluid pressure is released, creating an upward jarring force, releasing the stuck drill stem.
● Downward Jarring
Downward force is applied on the hydraulic jar, to create pressure in the working fluid of the lower hydraulic mechanism. When the jar reaches a predetermined stroke, the fluid pressure is released, creating a downward jarring force to release the struck drill tools.