... ground, move up and down in the well as a unit, and fixed in the tubing by seating ... The plunger is connected to the hold-down by a hollow pull tube and remains stantinary.The travelling barrel ... wall metal plunger, Thread configuration)Location of seating assembly: A(Top) B(Bottom) T(Bottom, Ttraveling)Type of seating ... of uper extensionLength of lower extention API 11 AX subsurface sucker rod pump