Gramophone motor with tachogenerator speed control - has disc type permanent magnetic rotor with non-magnetic bush between rotor disc and shaft

摘要

The electric motor has a drive motor with a flat air-gap in which a cove-less stator winding is located. These motors directly drive record players and a tachogenerator for speed control is incorporated in the motor. To minimise interference between the magnetic field of the motor rotor with the output winding of the tachogenerator, the motor is magnetically separated from the shaft. The ferromagnetic parts of the rotor structure are carred on a non-magnetic bush which fits on the motor shaft. The radial thickness of the bush is made as large as possible.