The power section of SGDF

The power section is the most important part of the downhole motor. SGDF defines a power section by its outer tube diameter, rotor/stator lobe configuration, and number of stages.

Stator & Rotor Cross Section


The power section is based on a principle developed by Rene Moineau. In any drilling application, the power section of the motor is the heart of a drilling motor. With different connections at two ends, it is a customized universal part in the motor industry. It converts the hydraulic energy of the drilling fluid into mechanical energy, creating high output torque in the process. The power section places high demands on the elastomer, so as to endure difficult drilling conditions. The elastomer transmits mechanical energy through a universal joint and transmission system to the PDC bits. In the end, the rate of penetration in highly increased.

SGDF now provides power sections ranging from 73mm to 244mm (also 2 7/8inches to 9 5/8 inches).


The rotor and stator are designed as helical elements with a major and minor diameter. The lobe is a curved spiral shape formed by the difference in the major and minor diameters.

The stator has one more lobe than the rotor. The difference in lobes creates a fluid inlet area (cavity) into which fluid can be pumped to create rotation. A stage is the distance measured parallel to the axis between two corresponding points of the same spiral lobe. This distance is commonly referred to as the lead of the stator.

The torque and speed rate can be varied by changing lobes and stages. A motor with more lobes can generate more torque; a motor with fewer lobes can have a higher rotational speed rate. On the other hand, the torque can be increased by adding more stages.

There are two ways to increase torque: First, increase the number of rotor/stator lobes; second, increase the number of stages of the power section.

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