Cover drives for crucible induction furnaces are available in a wide range of versions. Flap covers or sliding covers are normally operated by means of differential cylinders and chains. If cover hoods are being used, the drive takes the form of 2 differential cylinders. Swivel covers are driven via a curved roller and guide cylinder by means of a vertically acting plunger cylinder. The lowering takes place under the own weight of the cover and the piston rod. In case of certain special requirements, a small differential cylinder can also be used.