Abstract: A screening mechanism which has two ladder-shaped frame systems with spaced parallel ladder stringers and spaced parallel ladder rungs extending between the stringers, wherein at least one of the said frame systems is moving relatively to the other frame system to form sieve zones of continuously changing width with alternating dips of a different depth, curved arches or a different tension in a stretched condition, whereby at least one of the said frame systems is connected to a driving means such as a crankshaft, electro-magnets, pneumatic or hydraulically driven cylinders or the like and is held on link springs, swing supports, rollers, suspended swings, cables, swing metals or the like, while the other frame system is moving by the same driving means shifted by 180.degree..

Abstract: A transporting, sieving or filtering base or bottom consists preferably of extensible or bendably elastic materials and is divided into zones and supported. The individual zones are fixed between transverse elements or carriers which either belong to a driving frame system or constitute transverse braces of a frame or other supporting elements. The invention is particularly characterized in that the carriers or transverse braces limiting the zones have supporting or moving elements which make them movable individually upon a corresponding sliding roller and an elastically movable guiding path or in an elastically movable guiding profile. The movement is so carried out that the carriers or braces are shiftably coupled with each other while moving in the same direction in or upon these elements when the cross-sections connecting them reach their greatest possible longitudinal extension.

Abstract: A device for sieving, sorting, filtering and the like, comprising two frame systems movable relatively to each other, each frame system comprising a number of carriers extending in the sieving direction and moving parallel to one another, said frame systems interengaging in such a way that one carrier of one system is always adjacent within a certain distance to one carrier of the other system.