A brushless DC motor has a rotor with impeller blades mounted thereon to pump blood through the central portion of the motor. Over a portion of its length, the rotor has a cylindrical surface that is spaced from a cooperating cylindrical surface on the motor stator. There is a gap between these cylindrical surfaces through which there is a leakage flow of blood. The relative motion between the cylindrical surfaces provides a hydrodynamic bearing that suspends the rotor in the stator.
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