DESCRIPTION This invention concerns a machine with a mobile grid 5 for the el imination of sol id products, transported by a l iquid flow, from channels and similar.

More particularly this invention refers to a machine of the abovement i oned type formed so as to real ise, .by means of a mobile grid combined ith a fixed grid, a transport system J_Q adapted to withdraw the sol id product from the flow of l iquid carrying it and discharge it at a higher level from where the said product is removed- One such l ifting and transport system has been known for some time, but the arrangements which real ise it give 15 rise to various difficulties.

One of the difficulties of these known arrangements is the poor rigidity of the supporting structure due essentially to the fact that the restraining wall.s a r e mobile. Since the mobile walls must be sufficiently l ight and unencumberi ng so 0 as not to hinder the motion, these are not able to contribute sufficiently to the achievement of a good structural rigidness, being, furthermore, subject to hydrodynamic thrust

and vibrat ons which restrike the mobile group walls and the said connected walls. One such difficulty is particularly notab e in heavy uses of the machines depending generally on the high cc tent of solid products in the flow, on the product type, on the pipe configuration and on other factors well known to an expert in the art.

Another difficulty met in the known technology is the difficulty of realising reliable machines with a high discharge height this being due to the abovementioned difficulty regarding the poor rigidity of the supporting structure .

A further difficulty, also due to the poor rigidity of the supporting structure, consists of the width li itation and therefore the limitation of the machine's use. Furthermore this the use limitation of conventional machines is due to the fact that conventional machines a re equipped with driving means of the mobile group, that is electric motors which cannot be immersed in liquid and therefore such m.achines cannot be used in channels or similar, in which the level of the liquid is subject to considerable changes in level .

In the conventional machines it is, furthermore, necessary to provide a means of seal ng with the supporting structure, such means is subject to rapid wear and tear, the possibility of clogging and leaking and therefore reduction

in the machine's performance.

The object of this invention is to produce a machine of the abovementi oned type which substantially eliminates the difficulties encountered with conventional machines. This and other objects, characteristics and advantages are evident to a person skilled in the art from the following detailed description and from the appended claims.

The mobile grid machine for the elimination of solid products transported by a liquid flow from channels and similar according to the present invention is characterised by the features indicated in the characterising part of claim 1, further characteristics are indicated in the dependent clai s from 2 to 12.

A preferred form of embodiment of the machine is illustrated - only exemplifying but not l imiting - in the figures of the attached sheets of drawings, where:

- Figure 1 is a perspective view of the machine as a whole;

- Figure 2 is a perspective view of the fixed group only;

- Figure 3 is a perspective view of the mobile group only with parts removed for greater clarity;

- Figure 4 s a perspective view of an element of the mobile group;

- Figure 5 is another simplified perspective view of the tnachine as a whol e ; - Figure 6 is a perspective view, with parts removed for

greater clarity, of an element of the mobile group and of the driving means ; and

- Figure 7 illustrates the various positions of the mobile group during a movement cycle. With reference to the above figures, the machine indicated generally in 1 as a whole - is of the type comprising conventionally a first mobile group 2 and a second fixed group 3 of elements formed as steps so as to permit, as a consequence of the movement of the mobile group, the raising and transport from one step to the next in the sieved ateri al .

Machine 1, as is known, is destined to be positioned in any duct and to remove the solid material transported by the liquid flowing in the duct from said liquid. The elements of the fixed group are joined to a supporting structure essentially composed of two lateral plates 4,4' joined by upper crossbeams 5 and lower crossbeams 5' . The said lateral plates 4,4' have a profile which is variable as a function of the desired incl ination and dimension of the machine.

Elements 2 of the mobile group a re joined together by crossbeams 6 which a re in turn fixed to longitudinal members 7, 7' to which the motion is transferred by arms 8,8' on the exterior of the plates 4,4'. As shown by the figure, the arms 8 are made up of two elements joined together by an

oscillating joint 9, while the arms 8' are al so constituted by two elements which a r e bolted together.

The arms 8,8' a r e joined to cams 10, which receive the motion from a driving unit 11. The particular two-element form of the arms 8,8' al lows easy removal of the mobile group and relative elements 2 from the body of the machine 1 maintaining the position of the whole driving mechanism unchanged. The advantage of not having to interfere with the driving mechanism together with the use of reference keys, conventional in itself, on all the particulars of the motion transmission avoids proble s of phase displacement between the two groups and greatly reduces the servicing times for repairs and/or maintenance.

With reference to Fig. 6, the movement of the mobile group 2 is obtained by means of pairs of pistons 18 and 19, situated substant ally vertically and horizontally or sl ightly incl ined, respectively, hinged on inferior crossbeams 5' and of which the piston rods 18' and 19' a r e hinged to longitudinal members 7,7' . For a regular movement of the mobile group there are (as in the illustrated example) two pair of pistons 18 and 19 positioned next to the lateral plate 4 and two pairs positioned next to lateral plate 4' .

The pistons 18 and 19 are of hermetically sealed type and so these, controlled by a suitable control box 20, can operate even when immersed in l iquid thus machine 1,

according to the invention, can be used in channels, or similar, in which the level of liquid varies considerably.

The movement of the mobile group 2 is outl ined in Fig. 7: - In the position 0(4) - the mobile group 2 and the fixed group 3 are perfectly aligned, in phase - the piston rods 18 are in and the piston rods 19' a re out (with respect to the relative pi stons) ;

- In position 1 - mobile group 2 raised, the piston rods 18' are moved out and the piston rods 19' remain out;

- In position 2 - mobile group 2 moved forward, the piston rods 18' a re out and the piston rods 19' remain out;

- In position 3 - mobile group 2 lowered, the piston rods 18' are moved in and the piston rods 19' remain out; - In position 4 (0) - mobile group 2 moved backwards, the piston rods 18' remain in and the piston rods a r e moved out;

- after this, the cycle repeats itself as described above.

As shown in detail in Fig. 4, each element 2 has the points 12 of the steps curved alternativel in opposite directions with respect to the plane of the said element, said curved parts having the function of breaking up any lumps and/or filaments of sieved material .

The mobile elements 2 and fixed elements 3 have * the upper part at least from the last step equipped with a boss 13 destined to prevent the sieved material from falling down

a g a i n .

As results from the above, the structure of the machine 1 gets round al l the difficulties encountered in the known technol ogy . The use of fixed lateral plates 4,4' allows the real isation of machines which are robust and thus insensitive to hydrodynamic thrust and vibrations, of increased height and width according to necessity and without requiring the use of seal ing means. The hermetically sealed piston system, as al ready said, can operate even when immersed allowing the mac ine to be used in any type of channel , or similar, and finally allows a remarkable energetic saving with respect to existing systems.