DE4316147A1 - Machine for comminuting solid waste - Google Patents

Abstract

A machine for comminuting large awkwardly shaped pieces of waste has a main comminuting unit (10) and a preliminary comminuting unit (12) arranged above the latter. The preliminary comminuting unit (12) has a preliminary comminuting rotor (18) which interacts with preliminary comminuting counter tools (38, 40) which are fixed to the casing. The preliminary comminuting rotor (18) also supports a conveying spiral (26) which delivers the pieces of waste which have been subjected to preliminary comminution via the charging aperture (50) of the main comminuting unit (10). The latter has two comminuting rollers (54L, 54R) which run in opposite directions and interact with a fixed twin counter tool (62). The top of the counter tool (62) supports a narrow deflector body (94) which is guided up to the vicinity of the charging aperture (50). <IMAGE>

Description

The invention relates to a machine for crushing solid waste according to the preamble of claim 1.

Such machines are from different manufacturers in particular for shredding residual wood in the trade offered.

For some applications, it would be desirable to have such Machines with a higher shredding capacity are available to have. An increase in shredding capacity could basically be done so that the length of the Zer reduction roller and the one working with it Counter tool enlarged. On the one hand, this has the Disadvantage that for a significant increase in capacity the footprint of the shredder is strong is increased. In addition, the price of the shredder rises tion rollers, which usually have a solid roller core have, with increasing length disproportionately, and it there are also difficulties in hiring one consistently large game between the shredding tools and the counter tool.

The present invention is therefore intended to comminute nerungsmaschine according to the preamble of claim 1 be trained so that with a compact installation surface a significant increase in size reduction capacity is maintained.

This object is achieved by a Zer reduction machine according to claim 1.

In the shredding machine according to the invention, one has  two counter-rotating shredding rollers, the un ter interposition of only the two counter tools run indirectly side by side. So you have in axial Direction no increase in size; the enlargement the size in the direction perpendicular to this is small, because much of what is needed in this direction Space from previously unused parts of the Ge housing of the shredder can be removed. In particular, there is a space saving through over lapp in the collecting room.

Another advantage of the shredding according to the invention machine is that the most important parts of the real small shredding plant, even while lying machines in the program, namely the crushing rollers and the counter tools and which partially enclose the shredding rollers the sieves (compare claim 2).

For reasons of mechanical stability, the from the free area of the two counter tools have a certain remaining width. With the continuing education of the Er Finding according to claim 3 ensures that about the counter tools do not form a material jam.

The developments of the inventions according to the An sayings 4 and 5 serve a congestion-free feeding of good to be crushed to the areas of engagement between the two shredding rollers and the two counter tools.

Here has a cross-sectional geometry of the deflector body, as specified in claim 6, as special proved advantageous.  

With the development of the invention according to claim 7 achieved that the deflector body well against tilting is secured.

The development of the invention according to claim 8 is in With regard to high throughput of the shredding machine advantageous. She has a shredding roller very much right now to process hard and unfavorable material, can the other shredding roller with high Zer working capacity. Because of the non-uniform Works of the two shredding rollers are also on the upcoming masses of material exerted vibrations, which slides well into the areas of engagement guarantee.

With the development of the invention according to claim 9 ensures that both crushing rollers through Can reverse direction reversal if there any pieces of material should be jammed. Ge straight under conditions where one of the crushing roller reverses while the other shredding roller continues in the direction of work, you get strong shock the upcoming waste to be shredded, through which entanglements in the waste are released.

The development of the invention according to claim 10 with regard to little effort for the discharge of the shredded waste is an advantage.

Is used for the shredding rollers tools with the geometry specified in claim 11, so you get a particularly high shredding performance.

The development of the invention according to claim 12 is in terms of low tooling costs and long overall  Service life of the shredding tools is an advantage.

The shredding performance of the shredding according to the invention machine can be further increased by that they are loaded with pre-shredded waste material, in which the individual parts were not extremely different size. A particularly suitable for this shredding unit is specified in claim 13. A such pre-shredding unit is particularly suitable for pre-shredding extremely bulky waste play of pallets no longer usable and the same.

The development of the invention according to claim 14 is in With regard to the mechanically particularly simple structure of the front shredding unit is advantageous because the pre-shredding and the discharge of the waste pieces obtained here under Can use the same engine and a ge separate shaft for the conveyor spiral is saved.

In a shredder according to claim 14 need the pre-shredding tools only have small dimensions to have; they are also easy to get on with drive shaft connected.

The armoring of the pre-shredding tools according to An saying 16 is in terms of long life and lower Tool costs an advantage.

The detachable attachment of the pre-shredding tools according to Claim 17 facilitates the maintenance and repair of the Vorzer reduction unit.

According to claim 18 one sees at least two sets of fixed standing pre-crushing counter tools, so receives  a particularly uniform pre-shredding with high Throughput.

The development of the invention according to claim 19 is in With regard to the long service life of the pre-shredding counter tools and high mechanical strength of the same from Advantage.

Are given according to claim 20 of the discharge opening of the Vorzer smaller unit seen in the conveying direction increasing Width, you get a uniform distribution of the pieces of waste obtained during pre-shredding via the Filling opening of the main shredding plant.

With the arrangement according to claim 21, the smaller pieces of waste obtained in the pre-crushing are distributed substantially uniformly over the different axial regions of the comminution roller
For applications in which funds for lifting the waste to be shredded above the upper edge of the storage container are not available, one can lower the loading edge of the storage container by choosing the geometry specified in claim 22.

The development of the invention according to claim 23 enables it is light that the pre-shredding counter-tools carry move the wall section to jammed pieces of waste to get free or a slip of waste favorable.

The moving away of this wall section and its return internal pressure is carried out with that specified in claim 24 Mechanics reliable and faulty even in long-term operation free.  

The invention will now be further elucidated by way of example play explained with reference to the drawing. In this show:

Figure 1 is a side view of a multi-stage pulverization machine for bulky waste such as pallets, with part of a wall of a pre-shredding unit broken away.

Fig. 2 is a vertical section through the shredding machine shown in Fig. 1 along the section II-II there;

Fig. 3 is a similar section to Figure 2, but only the actual shredding area of a main shredding unit is shown, which is somewhat modified in details compared to Figure 1, and a block diagram of a control unit for the main shredding unit.

Fig. 4 is a plan view of part of the shredding unit of the main shredding unit according to Fig. 3;

Fig. 5 is a side view of a portion of the Vorzerkleinerungsrotors Vorzerkleinerungs unit according to FIGS. 1 and 2;

Fig. 6 is an axial end view of the pre-shredding rotor of the pre-shredding unit;

Fig. 7 is a plan view of a part of a size reduction with Vorzer-counter tools equipped WALL COMP-section of the Vorzerkleinerungseinheit;

Fig. 8 is a side view of a modified two-stage crushing machine;

Fig. 9 is a central diagonal section through a grinding tool for Hauptzerkleine approximation unit or the crusher shown in Figures 1, 2. 9;

FIG. 10 is a section through a Vorzerkleinerungswerkzeug for shredding Vorzerkleinerungseinheit the inference engine of Figures 1 and 2 and 9, respectively. and

Fig. 11 is a transverse section through a abgewan punched reservoir for a Vorzerkleinerungs unit of a crusher according to FIGS. 1 and 2 and 9 respectively.

In Figs. 1 and 2, a two-stage crushing is machine for bulky waste material such as wooden pallets or Preßspanmaterial reproduced, consisting of a generally designated 10 primary crushing unit and an over there arranged, generally designated 12 Vorzer size reduction unit.

The pre-shredding unit 12 has an upper, funnel-shaped housing part 14 and a lower, funnel-shaped, lower housing part 16 . These two housing parts are screwed together on flanges, as is common in apparatus construction, which, like similar connections, does not need to be described in detail below. Since vertical ribs 17 stiffen the lower housing part 16 .

A pre-comminution rotor 18 is arranged in the lower housing part 16 and has a roller core 19 . The latter carries at the end on the left in the drawing a shaft section 20 which runs in a bearing 22 . The right in the drawing end of the roller core 19 also carries a shaft section, which is not visible in the drawing and runs in a bearing, which is to be thought behind a working on the pre-shredding rotor 18 elec trical gear motor 24 .

A conveyor helix 26 is arranged on the roller core 19 .

As can be seen in particular from FIGS. 5 and 6, the conveyor helix 26 carries four circumferentially offset pre-shredding tools 28 on each gear, which are fixed in the circumferential direction by positioning strips 30 and are fastened by screws 32 running in threaded bores of the conveyor helix 26 .

On the back of each spiral aisle, three triangular stiffening elements 34 are provided lying behind the pre-shredding tools 28 , which core is welded to the roller and the back of the spiral.

As can be seen from Fig. 6, the end faces of the comminution tools 28 are at a clearance angle f. The pre-shredding tools 28 consecutive gears of the conveyor helix 26 are offset from each other in the direction of rotation, in the embodiment by 45 °.

As can be seen in more detail from FIG. 10, the pre-shredding tools 28 are provided with armor 36 made of wear-resistant material in their section above the conveying helix 26 .

The pre-shredding tools 28 work with two sets of pre-shredding counter-tools 38 , 40 , which are supported by the rear wall 42 of the lower housing part 16 in FIG. 1. As can be seen from Fig. 7, the two sets of pre-shredding counter-work 38 , 40 lie on two vertically spaced lines and are offset by half a pitch.

Each pre-shredding counter-tool has a trapezoidal tool section 44 in union which has a trailing edge and a vertical leading edge according to the inclination of the wall 42 . The tool sections 44 are nested and welded to their upper third with a triangular reinforcement plate 46 , which is welded to the wall 20 with its rear edge as well as the rear edge of the tool sections 44 . The division of the pre-shredding counter-tools 38 , 40 and their axial dimensions are each such that between them one of the pre-shredding tools 28 passes.

As can be seen from Fig. 2, the Hauptzerkleinerungsein unit 10 has a housing 48 which is provided at the center of its upper wall with a filling opening 50 . The shredding unit 10 is mirror-inverted to its vertical len in Fig. 2 perpendicular to the plane of the drawing center plane. Corresponding parts of the main grinding unit are distinguished below and in the drawing by the appended letters "L" and "R" where necessary. Reference numerals in the text below and the drawing, which contain no additions "L" and "R", should apply equally to both halves of the main comminution unit 10 .

From the filling opening 50 two guide walls 52 run downward, which represent extensions of the walls of the lower housing part 16 of the pre-shredding unit 12 . Two comminution rollers, generally designated 54 , are arranged under the guide walls 52 , which run around horizontal axes parallel to the axis of the pre-comminution rotor 18 . The shredding rollers 54 have a whale core 56 and on this shredder 58 (see FIG. 3), the tips of which pass through a path 60 .

The crushing tools 58 have a square shape when viewed from above. A counter tool 62 , which cooperates with the two comminution rollers 54 , has recesses 64 which spring back from its two longitudinal edges and which have the shape of isosceles right-angled triangles, as can be seen from FIG. 4. Through the recesses 64 NEN crushing tools 58 can pass through with little play.

Such as 3 and 4 can be seen from Fig., 56 annular grooves 66 are in the rolls core inserted, having the same cross sectional geometry as the recesses 64, the outer edges of the remaining between the annular grooves 66 webs inputting the tips of the between the recesses 64 verblei The bridges are again under a small distance.

As can be seen from FIGS . 3 and 4, four tool carriers 68 are welded evenly distributed in the circumferential direction in the ring grooves 66 , each of which removably carries one of the cutting tools 58 . For this purpose, the tool holder 68 are provided with (with respect to the crushing tools 58 central) threaded bores 70 which cooperate with fastening screws 72 running through the crushing tools 58 . As can be seen from FIGS . 3 and 4, the halves of the crushing tools 58 each fit positively in the associated ring groove 66 , while their free edge edges essentially represent an extension of the side walls of the adjacent ring grooves 66 .

As can be seen from Fig. 9, the crushing tools 58 each have a spherically concave top 74 , and their side surfaces 76 are arranged at a small clearance angle g. As shown in Fig. 4, the side surfaces of the tool carrier 68 are set back from the side surfaces 76 of the crushing tools 58 .

The counter tool 62 , which in practice can also consist of two mirror-image individual parts, is supported by a carrier 78 , which in turn is firmly connected to the housing 48 .

From the underside of the counter tool 62 to the lower edge of the guide walls 52 extend partially cylindrical perforated sieves 80 , the holes of which are arranged offset by half a pitch in successive axially parallel rows.

Below the perforated sieves 80 in the exemplary embodiment according to FIG. 2, an essentially W-shaped cross-section has a collecting container 82 , at the deepest points of which two screw conveyors 84 rotate, which are driven by assigned motors 86 and convey the comminuted material in a lateral direction to outlet connection 88 where it is taken over by another conveyor, for example a blow conveyor.

Roughly speaking, the comminution machine shown in FIGS. 1 and 2 works as follows:
The pallets to be shredded are placed in the upper housing part 14 of the shredding unit 12 . Before shredding rotor 18 disassembles them together with the shredding counter tools 38 , 40 into larger fragments, which are moved to the left by the conveyor spiral 26 in FIG. 1 and through a discharge opening 90 which lies in a position above the center of the filling opening 50 Intermediate wall 92 of the pre-shredding unit 12 is provided. From there, the pre-shredded material falls down and is passed through a deflector body 94 placed on the counter tool 62 either into the engagement area between the shredding roller 54 L and the recesses 64 L or the engagement area between the shredding roller 54 R and the recesses 64 R. The deflector body 94 has the shape of a strip with an acute triangular cross section and extends over the entire length of the counter tool 62 .

The material shredded by the shredding rollers 54 and the counterwork 62 falls through the holes of the perforated screens 80 and is discharged through the screw conveyors 84 .

FIG. 3 shows details of the excitation of motors 96 which operate on the comminution rollers 54 .

In the connecting line from a motor control unit 98 to the corresponding motor 96 , a power meter 100 is inserted, which in practice can simply be an ammeter. The output signal of the power meter 100 is passed to the one input of a comparator 102 , which receives at its second input a reference feature assigned to the maximum permissible power, which can be set, for example, on a potentiometer 104 . The comparator 102 always generates an output signal when the actual power is greater than the target power. The rising edge of this signal triggers a monostable multivibrator whose period can be set, as indicated by an arrow. The output signal from the monostable multivibrator 106 arrives at a control input of the engine control unit 98 and causes the engine control unit 98 to reverse the direction of rotation of the associated engine 96 for the duration of this signal. In this way, pieces of waste that have become wedged between the assigned comminution roller 54 and a fixed housing part or the counter tool 62 are released again.

As shown in FIG. 3, separate controls of this type are provided for the two motors 96 L and 96 R, which are supplied from a common feed line 108 , which is connected to the three-phase network via a main switch 110 .

In the exemplary embodiment according to FIG. 3, instead of the W-shaped collecting container 82, a V-shaped collecting container 82 is provided, at the lowest point of which only a single screw conveyor 84 is provided. Their motor 86 is just in case connected to the feed line 108 .

In the modified shredding machine according to FIG. 8, the pre-shredding unit 12 is placed at an angle so that its motor-side end rests on the installation surface, while its discharge end stands above the center of the main shredding unit. For this purpose, the dead space of the housing 48 located at the top right in FIG. 8 is correspondingly chamfered. In the pre-shredding unit 12 , the intermediate wall 92 is omitted and a continuation 112 of the conveyor spiral 26 is arranged on the shaft section 20 . A conveyor trough 114 extends around this and is provided with a discharge opening 116 at the lower left end. Their width increases as seen in the conveying direction, as a result of which the waste pieces discharged are again distributed over the two comminution rollers 54 L and 54 R.

As can be seen from Fig. 8, the deepest, there right edge of the upper housing part 14 is only slightly higher than if the pre-shredding unit 12 would be arranged next to the main shredding unit 10 on the footprint. The upper housing part 14 is loaded with the pallets or the like to be shredded via this relatively low edge, which can also be done by hand. In order to convey the pre-shredded material upwards to the filling opening 50 , no separate conveyor is required, despite the lower loading edge, which would cause additional costs. In practice, the gravity feed of the pallet to be shredded or the like for the pre-shredding rotor is also sufficient in the embodiment according to FIG. 8.

In the exemplary embodiment according to FIG. 11, the wall 42 carrying the shredding counter-tools 38 , 40 is fastened to the housing of the shredding unit 12 via joints 118 . By side tension springs 120 acting on the wall 24 , the wall 42 is biased in the direction of the pre-crushing rotor 18 away. An eccentric roller 122 is provided between the tension springs 120 and works together with the lower portion of the outside of the wall 42 and is rotated by a motor 124 .

The motor 124 can be excited manually by means of a switch 126 if a jam is observed in the storage container of the pre-shredding unit 12 . Alternatively or additionally, the motor 124 can also be activated via a time control 128 which operates at predetermined regular intervals. Alternatively or additionally, motor 124 can also be energized when the current drawn by geared motor 24 exceeds a predetermined value.

In a further implementation of the invention, one can also provide a reversing mechanism for the geared motor 24 , as described in FIG. 3 for the shredding rollers 54 of the main shredding unit 10 .

Claims (24)

1. Machine for crushing solid waste, with egg ner crushing roller ( 54 L), the surface on its outer surface with a plurality of protruding crushing tools ( 58 ), which are arranged in relation to the roller axis transverse tool planes, the tool planes preferably are equidistant and preferably, the shredding tools are at least directly adjacent tool levels in the direction of rotation against each other, and with a counter tool ( 62 ) which runs parallel to the axis of the shredding roller ( 54 L) and on its side facing the shredding roller ( 54 L) the tool planes have aligned recesses ( 64 L) through which the shredding tools ( 58 ) can pass with play, with a partially cylindrical perforated sieve ( 82 L), which, viewed in the direction of rotation, lies behind the counter-tool ( 62 ) section of the shredding roller ( 54 L ) partially encloses, and with one the Ze Reducing roller ( 54 L) and the counter tool ( 62 ) surrounding housing ( 48 ), which has a collecting container ( 82 ) for crushed waste lying under the perforated screen ( 80 ) and one over the area of engagement between the crushing roller ( 54 L) and counter tool ( 62 ) lying filling opening ( 50 ) for waste to be shredded, characterized in that a second counter-tool ( 62 ) and a second shredding roller ( 54 R) extend parallel to the counter-tool ( 62 ) at a small distance, which in an analogous manner as the first shredding roller ( 54 L) and the first counter tool ( 62 ) are provided with shredding tools ( 58 ) or recesses ( 64 L); that the second comminution roller ( 54 R) is surrounded by a partially cylindrical second perforated screen ( 80 R); that the second shredding roller ( 54 R) rotates in the opposite direction of rotation as the first shredding roller ( 54 L); and that the filling opening ( 50 ) also extends over the engagement area between the second shredding roller ( 54 R) and the second counter tool ( 62 ). 2. Shredding machine according to claim 1, characterized in that the two shredding rollers ( 54 L, 54 R), the two counter tools ( 62 ) and the two perforated sieves ( 80 L, 80 R) related to the center plane of the counter tool ( 62 ) are mirror images of each other. 3. Crushing machine according to claim 1 or 2, characterized in that a deflector (94) is disposed above the counter-tools (62) which extends over the entire length of the ge counter tools (62). 4. Shredding machine according to claim 3, characterized in that the longitudinal edges of the deflector body ( 94 ) are closely adjacent to the inner base points of the recesses ( 64 ) of the counter tools ( 62 ). 5. Shredding machine according to claim 3 or 4, characterized in that the deflector body ( 94 ) up to the uppermost point of the web ( 60 ) of the shredding tool ( 58 ) is pulled up. 6. Comminution machine according to claim 5, characterized in that the transverse cross-section of the deflector body ( 94 ) has the shape of a small opening angle on pointing isosceles triangle. 7. Comminution machine according to one of claims 3 to 6, characterized in that the deflector body ( 94 ) is fixedly connected to the counter tools ( 62 ). 8. Shredding machine according to one of claims 1 to 7, characterized in that the two shredding rollers ( 54 L, 54 R) are driven by independent motors ( 96 L, 96 R). 9. Shredding machine according to claim 8, characterized in that each of the motors ( 96 L, 96 R) is assigned a lei meter ( 100 L, 100 R); that a comparator ( 102 ) is connected to the output of the power meter ( 100 ), which is also assigned a reference signal ( 104 ) assigned to the permissible maximum power; and that the output signal of the comparator ( 102 ) is in each case given via a timing element ( 106 ) to a control input of a motor control unit ( 98 ) which, for the duration of this signal application of its control input, reverses the direction of rotation of the motor ( 96 ) excited by it . 10. Shredding machine according to one of claims 1 to 9, characterized in that the collecting container ( 82 ) has a V-shaped cross-section and at the lowest point of the symmetrical to the central plane obliquely downwards from falling side collecting container walls, a single removal conveyor ( 84 ) is provided. 11. Shredding machine according to one of claims 1 to 10, characterized in that the tool ( 62 ) cooperating surface ( 74 ) of the shredding tools ( 58 ) is spherically concave. 12. Shredding machine according to one of claims 1 to 11, characterized in that the shredding machine ( 58 ) seen in supervision have the shape of an equilateral triangle or a square and have a central mounting hole so that they can be implemented with a with a roller core ( 56 ) connected tool carrier ( 68 ) can be connected. 13. Shredding machine according to one of claims 1 to 12, characterized by a pre-shredding unit ( 12 ), which in turn has: a storage container ( 14 , 16 ) for bulky waste to be shredded such as pallets or the like, one at the deepest point of the storage container ( 14 , 16 ) arranged pre-comminution rotor ( 18 ) which is equipped with pre-comminution tools ( 28 ) which are arranged in preferably equidistant tool planes which are transverse to the axis of the pre-comminution rotor ( 18 ) and which are located between a lower wall section ( 42 ) of the storage container ( 14 , 16 ) lying before comminution counter tools ( 38 , 40 ) can pass through with play, and a conveyor ( 26 ; 112 ) for moving the waste pieces obtained during the pre-comminution to a discharge opening ( 90. ) Formed in the storage container ( 14 , 16 ) ; 116 ); and by means for conveying the pre-shredded pieces of waste from the discharge opening ( 90 ; 112 ) of the storage container ( 14 , 16 ) to the filling opening of the main shredding unit ( 10 ). 14. Shredding machine according to claim 13, characterized in that the conveying device is formed by a conveying helix ( 26 ; 112 ) carried by the pre-shredding rotor ( 18 ). 15. Shredding machine according to claim 14, characterized in that the pre-shredding tools ( 28 ) are carried by the conveyor helix ( 26 ) and protrude radially beyond the free edge. 16. Shredding machine according to claim 15, characterized in that the pre-shredding tools ( 28 ) are armored with a hard wear layer ( 36 ). 17. Shredding machine according to claim 15 or 16, characterized in that the pre-shredding tools ( 28 ) releasably ( 32 ) on the conveyor helix ( 26 ) are attached. 18. Shredding machine according to one of claims 13 to 17, characterized in that at least two pre-shredding counter tool sets ( 38 , 40 ) in different vertical positions on the lower wall section ( 42 ) of the storage container ( 14 , 16 ) of the pre-shredding unit ( 12 ) are arranged, the two counter-tools are shifted by a division against each other. 19. Shredder according to one of claims 13 to 18, characterized in that the pre-shrinking counter tools ( 38 , 40 ) are armored with a wear material and have the shape of flat vertical material sections which have a longitudinal edge on the lower wall section ( 42 ) of the storage container ( 12 , 14 ) are welded and in their upper third are additionally welded to the lower wall section ( 42 ) by means of three angular stiffening parts ( 46 ). 20. Shredding machine according to one of claims 13 to 19, characterized in that the discharge opening ( 116 ) of the pre-shredding unit ( 12 ) has an increasing width when viewed in the discharge direction. 21. Shredding machine according to one of claims 17 to 20, characterized in that the discharge direction of the pre-shredding unit ( 12 ) runs parallel to the axes of the shredding rollers ( 54 ) and the discharge opening ( 90 ) above the center of the filling opening ( 50 ) of the main shredding unit ( 10 ) lies. 22. Shredding machine according to one of claims 13 to 20, characterized in that the pre-shredding unit ( 12 ) is so inclined that its discharge opening ( 116 ) above the filling opening ( 50 ) of the main shredding unit ( 10 ) and it from the Discharge opening ( 116 ) end resting on the installation surface; and that an end portion ( 20 ) of the pre-shredding rotor ( 18 ) carries a conveyor helix ( 112 ). 23. Comminution machine according to one of claims 13 to 22, characterized in that the lower wall section ( 42 ) carrying the shredding counter-tools ( 38 , 40 ) of the storage container ( 12 , 14 ) is movable and by a drive ( 120 to 128 ) to the pre-shredding rotor ( 18 ) and this can be moved away. 24. Comminution machine according to claim 23, characterized in that the drive ( 120 to 128 ) a spring arrangement ( 120 ) for biasing the movable Wandabschnit tes ( 42 ) away from the pre-comminution rotor ( 18 ) and an eccentric roller driven by a motor ( 124 ) ( 122 ), through which the movable wall section ( 42 ) can be pressed onto the pre-shredding rotor ( 18 ).