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It consists of stator and rotor. Stator is made by squeezing rubber sleeve on the wall of steel tube. There forms spiral structure with a certain geometric parameter. Rotor is a chrome-plated screw rod.
Stator and rotor matches with each other, to form spiral line and seal cavity through their guide rail difference. With rotor running in the stator, the seal cavity is moving along its axial direction, continuously forms and disappears to complete its energy conversion. This is the basic principle of down-hole motor.
Spiral seal line on rotor is divided into single end and multi-end (stator with one more end than rotor). The less ends the motor has, the higher speed and the lower torque are. The more ends it has, the lower speed and the higher torque are. The following figure shows the sectional profile of several typical motors.
