A rotary plate makes it possible to support an element that is intended to be able to rotate. Such a rotary plate makes it possible for example to support a carousel so that its rotation can entertain persons on the carousel, for example on wooden horses in the most usual variants.
Conventionally, a carousel is rotated by a motor that is configured to drive the rotary plate supporting the rotating carousel. The use of such a motor is particularly necessary for large carousels. The rotation of the plate, and therefore of the carousel, depends on the operating speed of the motor, which makes it possible to control the speed of said rotation.
For smaller carousels, and therefore smaller rotary plates, it can be envisaged to not use a motor for the rotation: said rotation is therefore free and can be initiated manually, either by a person present on the carousel or by a person located outside it.
It is then possible to install a small carousel of this kind in an open place, such as a park or a square, and to leave it available to users without requiring the presence of a person responsible for managing the motor, as is the case with a larger carousel.
Nevertheless, leaving such a carousel without a motor available to users may pose certain problems, in particular if this carousel is located in a public place:                safety problems related to the use of the carousel without management personnel, in particular for children who should not use the carousel without supervision,        availability problems related to the lack of restriction of use, which may give rise to improper behaviour such as prolonged use.        
Thus, the rotation of the rotary plate must be controlled in order to satisfy all these requirements relating to the use of the carousel.