Double-acting jar

摘要: A double-acting jar is disclosed comprising: an outer housing; inner mandrel at least partially disposed telescopically within the housing to define a fluid chamber between and housing, containing being sealed; valve on one of having downhole portion that movable seated position in which seats against unseated position, restriction surface; uphole other cooperating surface cooperates with set for jar, dimensioned so that, from relative movement above below neutral incorporating first bypass configured allow when move past each during re-setting jar; second jarring surfaces respectively contact direction; direction.