An anode for the electrolysis of aluminium made from an outer dense layer of a ceramic material on a dense core made from a composite of the ceramic material of the outer layer and an electronic conductor. The second mobile has means of locking with the escapement wheel and means of mechanical transmission with the escapement wheel and the first mobile. The invention also provides processes for preparing compounds of the inventions. The slider is free to move in a direction of a translational plane within the housing thereby providing the translational degree of freedom.