seat 22 it may stop short of upper seat 22 but for up jarring with tension applied to top sub 10 fluid pressure in passage 18 will ultimately seat valve member 20 on upper seat 22 during down jarring slots 16 will permit flow to bypass valve member 20 through open opening 28 on impact cap 24 mounted around upper shaft 12 is upper sub 32 upper sub 32 is connected to main barrel 34 at thread 36 main barrel 34 has an impact shoulder 38 fig1 b and a thread 40 to attach the helix housing 42 at its lower end helix housing 42 has an internal helix 44 see fig8 whose purpose will be explained below within main barrel 34 is dart body 46 dart body 46 has a central passage 48 that terminates in one or more lateral outlets 50 surrounding dart body 46 are springs 52 and 54 spring perch 56 is supported off a shoulder on main barrel 34 and acts as the lower support for spring 52 an upper flange 58 on dart body 46 rests on spring 52 during run in dart bushing 60 rests on another internal shoulder in main barrel 34 and supports the lower end of spring 54 mounted above spring 54 is trip bushing 61 trip bushing.