倒扣接頭  

Reversing Subs

倒扣接頭也叫倒扣矛，是用來在鉆、修井過程中倒出卡點以上被卡鉆柱的專用工具。打撈或倒扣時，若落魚被卡或倒不開時，可從倒扣接頭處退開，取出打撈鉆具。

Reversing Sub is also calledreversing spear which is a special tool for reversing stuck drill stem abovestuck point in drilling and work over operation. When make fishing orreversing, if fallen object is stuck or fail to be released, the tool canreleased from thread connection of reversing sub to take out fishing tool.