The drilling jar is consists of drilling up jar and drilling down jar in one body, which has stable working performance and strong jarring force both up and down. When in down hole, it can release the struck; it is a desire tool for directional well and deep well

Working principle

 Up jarring

Lowering drill string to make drilling jar closed completely (in locking position), elevating drill string by the order of small tonnage to larger tonnage, which make spring and hydraulic cylinder delay, when mandrel move to a position and become release resistance, the spring force stored in drill string will transfer to upforward energy and up jarring. Repeating the above  several times can force tool to produce continues up jarring.

 

 Down jarring

Move up and down the drill string to make drilling jar closed completely (in locking position), lowering drill string to make spring compressed and stored energy. When pressure of jar is larger than the desired lower unlocking force, grapple will slide out from mandrel to release the locking and make down jarring. Repeating the above  several times can force tool to produce continues down jarring.