Lubricated fishing bumper sub is one of the jars which produce jarring force by means of the

energy caused by heavy weight objects when moving down,its inner chamber is full of hydraulic

oil so as to ensure a longer service life.The tool is suitable for deep hole and middle deep hole

operation.With some advantages:Can produce strong one way down jarring force,maximum

jarring force, continuous down jarring force. Medium jarring force;continuous up jar, low-grade

jarring force; can release fishing tool; can act as constant pressure drill tool, simply structure,

easy operation, all these make it widely used jarring tool.

Woking principle

● Energy conversion in jarring operation

Jarring downward is made by means of conversion. Rasing drill stem shall make bumper jar to

be pull down at a certain height to produce potential energy. Go on raising drill stem, the drill

stem has a strain energy due to spring strain. When drill stem is lowered suddenly, the energy

stored in drill stem the force the drill stem to move downward in acceleration. When bumper

sub reaches a closed position, the above energies at this instant change into a large downward

jarring force.

● Main factors having influenced on jarring force.

Many factors influence on jarring force.but key factors as follows:

1. The bigger hanging weight on top drill stem of bumper jar makes a bigger jarring force.

2. The longer the spring extension of drill stem is when raising drill stem.the bigger the jarring

force is.

3. The longer the stroke of the bumper jar is, the bigger the jarring force of jar is.