PRE-COAT FILTER

In the filter according to the invention (precoated filter), gap-type filter elements (11) designed in the manner of filter cartridges and consisting of a profile wire wound into a helical spring are used. In order to detach the adhering filter cake, the gap-type filter element (11) is stretched in its axial direction, with the filter gaps being opened at the same time, this appropriately being carried out be means of a stretching drive which at the same time can be designed as a vibratory drive. The gap-type filter elements are at the same time made to vibrate, and this can be obtained by means of periodic stretching and shortening or by making the stretched gap-type filter elements vibrate. The vibratory movement is appropriately executed at a frequency matching the natural frequency of the gap-type filter elements.