... Description:1.Magnetic levitation technology, no iron core, no hysteresis and cogging, low starting torque.2.No mechanical friction, above 98% of ... , small gap, high power density5.Low speed direct drive, No torque ripple6.Compact, high-volume power ratio7.Due to ... Diameter mm4019Materials of Case Aluminium Alloys20Materials of Shaft Carbon steel 2012 newest 400W Permanent Magnet Generator with 200rpm