DUAL-ACTING HYDRAULIC JAR Russian patent published in 2014 - IPC E21B31/113 

FIELD: mining.

SUBSTANCE: hydraulic jar comprises telescopically connected tubular case and hollow shaft. Said case comprises inner anvil ledges at mid section and splines. Shaft comprises first piston with seal, hammers between inner anvils, second piston making the chamber filled with working oil. It comprises also two limiting mechanisms of fluid communication with said chamber, each being equipped with shaft collar of enlarged diameter. Besides, it includes first and second ring valves, each being arranged in working oil chamber. Valve device to constrict fluid flow inside the chamber is arranged every valve. Said device includes valve module comprising valves body and body adapter, secured together. Valve seat, spacer, first and second circular channels are arranged inside valve body. Said valve module makes with hollow shaft the central part of said chamber filled with working fluid. valve body has inner circular collar. Through circular channel is arranged between spacer inner surface and outer surface of shaft collar of enlarged diameter. Through circular channel is arranged between valve seat surface and inner surface of shaft collar of enlarged diameter. Tubular case parts have smooth stepless cavity.

EFFECT: longer life, higher reliability.

3 cl, 5 dwg, 1 tbl