1. Attrition of drilling pipe is declined obviously for downhole screw motors running torque is only to drive bit while the drilling is not rotating;
2. Not only provide special drill assembly with high deflection rate, but also guide drill assembly with everlasting control;
3. Out torque and pressure difference is nearly liner relationship within a certain range when the power liquid flows into the screw motor;
4. Provide great delivery volume and improve speed of uphole velocity and carrying capability for rotor is hollow;
5. Suitable for all kinds of bits.
