One of the first electric mixers to be produced was the `Universal Electric Mixer Beater' in 1918. It consisted of a kitchen whisk connected to an electric motor. There were other food mixers created but they did not become popular until after World War II.
Small domestic food mixers work on a different principle to larger industrial ones. The design of these mixers features the usual whisking and beating actions. A pair of whisks (or beaters) are mounted vertically in such a way that they have little distance between them so the whisks can intermingle with each other. The whisks are driven in opposite directions by a pair of helical gears that are positioned on opposite sides of a worm gear. The worm gear is fixed straight on to the motor shaft. This contra-rotating action causes the substance to be drawn through the whisks and therefore mixed thoroughly.
Food mixers are generally fitted with universal motors, so that they can be powered from a direct current source. With motors of this sort the speed of the mixer can be controlled by means of a series of switches. A number of coils are wound on top of each other. The switch selects one of these and the chosen coil determines the necessary speed.
