Abstract:
A road paver ( 10 ) and a loader and a homogenizing mechanism ( 17 ) which permit optimum quality of the road building material without the operation of the road paver ( 10 ) or of the loader being impaired. Road coverings are customarily produced from materials such as asphalt by means of road pavers ( 10 ). In order to ensure optimum durability of the road covering produced, the road building material is homogenized by mixing devices prior to being laid. The continuous mixing of the road building material requires a very large amount of energy and results in severe wear phenomena in the mixing devices.

Description:
STATEMENT OF RELATED APPLICATIONS 
       [0001]    This application claims the benefit of German Patent Application No. 102015007800.3 having a filing date of 19 Jun. 2015 and German Patent Application No. 102015009530.7 having a filing date of 27 Jul. 2015. 
       BACKGROUND OF THE INVENTION 
       [0002]    Technical Field 
         [0003]    The invention relates to a road paver with a running gear, with at least one hopper for receiving road building material, with a paving screed for producing a road covering, and with a conveyor for conveying the road building material from the hopper to the paving screed. Furthermore, the invention relates to a loader with a running gear with at least one hopper for receiving road building material, with a conveyor for preferably continuously feeding the road building material from the hopper to a road paver for paving a road covering, in particular an asphalt layer or asphalt paving. The invention also relates to a homogenizing mechanism for homogenizing road building material, with a receiving space for receiving the road building material having at least one mixing element for homogenizing the road building material, and with at least one opening in order to feed the road building material to a further device. 
         [0004]    Prior Art 
         [0005]    Surface coverings or road structures, which can for example be walked or driven over, such as in particular carriageway coverings or road paving layers, in particular road pavings, are customarily produced from materials such as, preferably, asphalt. What are generally referred to as pavers, in particular road pavers, are used for producing the material layer that is applied on an underlying surface. 
         [0006]    The material is usually at least substantially continuously fed to the road paver in order to ensure an even application of material that is as uninterrupted as possible. As a buffer for short interruptions in delivery, the road paver generally has a container or hopper that is also known as a material bunker. The material is usually loaded into this hopper from what is referred to as a loader with the aid of a conveyor. The road paver itself usually also has a conveyor, preferably a scraper conveyor, which serves to remove material from the hopper and feed it to a paving screed. The paving screed distributes and compacts the material evenly on the underlying surface. The road paver can be designed as a single-layer or multi-layer paver. 
         [0007]    Surface coverings made from asphalt are processed when hot. In order to ensure optimum durability of the surface covering produced, it is necessary to avoid deviations of properties of the laid material, for example the processing temperature and/or the material composition, from predetermined values. Use is customarily made for this purpose of mixing devices which homogenize the material by mixing, in particular produce a homogeneous temperature distribution and a homogeneous distribution of the components of the material, prior to the laying of the road building material. For this purpose, the mixing device is deposited into the hopper of the road paver and serves equally as a container for receiving the road building material and as a homogenizer. The continuous mixing of the material being laid requires a very large amount of energy and results in severe wear phenomena in the mixing devices. Due to the high energy requirement, the homogenization is associated with an external energy source, in particular with the drive of the paver, and is therefore flexibly usable only to a conditioned extent. Furthermore, the increased energy requirement for the homogenization may reduce the overall power of the road paver or of the loader. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The invention is therefore based on the object of providing a road paver and a loader and a homogenizing mechanism which permit optimum quality of the material being laid without the operation of the road paver or of the loader being impaired. 
         [0009]    A road paver for achieving this object is a road paver with a running gear, with at least one hopper for receiving road building material, with a paving screed for producing a road covering, and with a conveyor for conveying the road building material from the hopper to the paving screed, characterized in that a mechanism for homogenizing the road building material can be positioned in the hopper, with at least one receiving space for receiving the road building material. According thereto, it is provided that a mechanism for homogenizing the road building material can be positioned in the hopper of the road paver, with at least one receiving space for receiving the road building material. The volume of the homogenizing mechanism or of the receiving space corresponds approximately to the volume of the hopper or is slightly smaller. By positioning the homogenizing mechanism in the hopper, the road building material can be homogenized directly before the road building material is fed to the paving screed or directly before the road building material is laid. As a result, directly before the laying, the road building material is blended in terms of its composition and temperature in such a manner that it can be applied uniformly on an underlying surface in a sufficiently blended and thermally homogeneous state. As a result, an optimum road covering can be produced. 
         [0010]    The present invention preferably furthermore provides that the homogenizing mechanism is an independent unit, in particular has a dedicated energy supply, preferably a dedicated motor, and therefore the homogenizing mechanism can be operated independently of the road paver. According to the invention, it is provided for this purpose that the mechanism outside the receiving space is assigned, for example, an internal combustion engine which drives the mechanism via driving means. The operation of the mechanism is therefore independent of the operation of the road paver. The energy generated by the engine of the road paver can equally be used completely for the production of the road covering and does not additionally have to ensure the operation of the homogenizing mechanism. Furthermore, this separation of the energy supply permits the operation of the homogenizing mechanism while the road paver is in, for example, a waiting mode in which the drive of the road paver is switched off at least temporarily. 
         [0011]    According to the invention, it is furthermore provided that the mechanism has, in the at least one receiving space, at least one mixing element which is preferably drivable in a rotating manner about a shaft parallel to a paving direction of the road paver by means of the motor of the mechanism, and in that the at least one mixing element has blades arranged radially about the shaft, wherein the shaft is preferably assigned a set of long blades and a set of short blades which are arranged in an alternating sequence along the shaft. The shaft of the mixing element is mounted in the receiving space or in the mechanism in such a manner that said shaft is rotatable and is directly connected to the engine. The blades which are attached to the shaft in a manner pointing radially outward are, for example, of wing-like design, wherein the wing can be flat, concave or convex. Furthermore, it is conceivable for the blades to have a “T” shape, wherein the base of the “T” is connected to the shaft. Various blades or various blade combinations can be connected to the shaft depending on the requirements imposed on the material to be mixed or on the road covering to be produced. According to the invention, it is provided that the “T”-shaped blades are arranged in an alternating manner with a short base and a long base along the shaft. Furthermore, the blades which are assigned to a common portion on each shaft can enclose different angles to one another. The blades are dimensioned in such a manner and the shaft is positioned in such a manner that they cover as large a volume region of the receiving space as possible and, during rotation of the mixing element, as large a portion of the road building material as possible is thoroughly mixed or ploughed through. 
         [0012]    In particular, the present invention furthermore provides that the homogenizing mechanism has two mixing elements, the shafts of which are oriented parallel to each other and which are preferably drivable so as to rotate in opposite directions to each other, wherein the distance between the blades, which rotate in opposite directions about the shafts, of the respective mixing elements is minimized, in particular in that the blades, which rotate in opposite directions, of the respective mixing elements overlap. It is thus conceivable, for example, that a short and a long blade of each shaft always lie opposite each other in such a manner that the mixing elements, inter-engaging in a corresponding manner, thoroughly mix or homogenize the road building material. The mixing elements can be driven at different speeds governed by the situation, but are also driven in a rotating manner independently of one another at different speeds or in different directions. 
         [0013]    A further advantageous refinement of the present invention can provide that the homogenizing mechanism has wheels with which the mechanism can be supported on an underlying surface, the wheels are preferably removable from the mechanism, and the mechanism can be fastened, in particular releasably, in the hopper. In particular in the case of a mechanism loaded with road building material, it is advantageous if the mechanism is at least partially supported by wheels. The entire weight is thus not loaded on the road paver and does not impair the driving properties thereof. In order to supply the road paver with road building material, the mechanism can be fastened in the hopper. However, it is also conceivable for the homogenizing mechanism to be positioned on the far side of the road paver and, when required, can be lowered onto the road paver or into the hopper by a lifting mechanism. During this, the road covering is preferably continuously homogenized in the receiving space of the mechanism. The wheels can be coupled to or decoupled from the mechanism, depending on the operating mode. 
         [0014]    Furthermore, it can be provided according to the invention that the homogenizing mechanism has at least one, in particular closable, opening through which the road building material is conveyed onto the conveyor, preferably in that the at least one opening in the homogenizing mechanism at least partially corresponds to an opening in the hopper. An advantageous exemplary embodiment of the present invention provides that the mechanism has an opening on a lower side. If the homogenizing mechanism is not located in the hopper of the road paver, but rather is mounted on the other side of the road paver, this opening is closed such that the road building material does not inadvertently pass onto the underlying surface. As soon as the road building material is sufficiently homogenized, this opening is opened, and therefore said road building material is transported on the conveyor of the road paver to the paving screed. 
         [0015]    A further possibility of refinement of the present invention makes provision that the homogenizing mechanism has a cleaning mechanism by means of which the receiving space and the at least one mixing element can be cleaned, and/or the mechanism, in particular the receiving space, can be heated by the motor, and/or the mechanism, in particular the receiving space has preferably thermal insulation. The cleaning mechanism cleans the homogenizing mechanism preferably with water or with a cleaning liquid or with an emulsion. As a result, it can be provided that the mechanism is assigned a plurality of spray nozzles which are connected to a liquid supply system. The entire interior of the homogenizing mechanism and also the shafts and the blades can be acted upon with the liquid by means of said cleaning mechanism, in particular with the spray nozzles. The interior is preferably cleaned after use of the mechanism. Road building material which has remained in the interior is thus rinsed off as long as the latter is still at a certain temperature. Furthermore, it is conceivable that the cleaning liquid additionally has an anti-stick agent which is intended to have the effect that, when the mechanism is reused, further material immediately solidifies in said mechanism. The liquid supply system comprises a tank which is directly connected to the mechanism, preferably is fastened to the mechanism. 
         [0016]    The present invention can preferably furthermore provide that the cleaning mechanism can be operated automatically, in particular depending on the degree of soiling, filling level of the mechanism with road building material, planned refilling of the mechanism and/or external conditions, such as temperature and humidity. For this purpose, the invention can make provision for the mechanism to have at least one sensor which determines the degree of soiling of the mechanism. If a soiling threshold value that is to be specified can be determined, the cleaning can take place. The mechanism can also have sensors for ascertaining ambient conditions, such as temperature. Depending on the measured values, the cleaning mechanism can be controlled automatically via a control mechanism. In addition, the drive of the shafts can be assigned a sensor for determining the load, wherein the mechanism is cleaned depending on the load on the drive. If the load is, for example, high relative to a reference value, although there is no road building material in the mechanism, the degree of soiling can be classified as being high. Furthermore, the controller of the cleaning mechanism can be connected to an onboard computer of the road paver or to a loader, and therefore the mechanism is cleaned only between two operations to fill it with new road building material. 
         [0017]    Furthermore, the receiving space is heated up by heating elements which are supplied with energy by the engine. So that the energy serving for heating up the road building material is not lost, the receiving space has thermal insulation. This is particularly advantageous in the event that the homogenizing mechanism is mounted away from the road paver. The mechanism can thus be deposited directly onto the road paver when required and the road building material can be laid. 
         [0018]    Furthermore, the present invention can furthermore provide that the at least one mixing element of the homogenizing mechanism can be exchanged, preferably in that the blades of the at least one mixing element can be exchanged. In particular, the mechanical, but also the thermal loading of the blades is very high because of the homogenization. The blades may therefore become worn or defective. In order to ensure continuous operation of the homogenizing mechanism and therefore little idle time, the blades are interchangeable in groups or individually. Furthermore, the blades can be interchanged individually depending on the requirements imposed on the mixing process, and therefore optimized mixing can take place for each road building material. 
         [0019]    A loader for achieving the object mentioned at the beginning is a loader with a running gear with at least one hopper for receiving road building material, with a conveyor for preferably continuously feeding the road building material from the hopper to a road paver for paving a road covering, in particular an asphalt layer or asphalt paving. According thereto, it is provided that the loader is assigned a mechanism for homogenizing the road building material, which mechanism can be positioned in the hopper and has a receiving space for receiving the road building material. Furthermore, it is provided according to the invention that the loader has the same features as the road paver described previously. 
         [0020]    A homogenizing mechanism for achieving the object mentioned at the beginning is a mechanism for homogenizing road building material, with a receiving space for receiving the road building material having at least one mixing element for homogenizing the road building material, and with at least one opening in order to feed the road building material to a further device, characterized in that the at least one mixing element can be driven by an energy supply dedicated to the mechanism. According thereto, the at least one mixing element is drivable by an energy supply dedicated to the mechanism. The at least one mixing element for homogenizing the road building material is assigned here to a receiving space for receiving the road building material. Said receiving space has at least one opening in a lower region in order to feed the road building material to a further device. This further device can be, for example, the conveyor belt of a road paver or of a loader. As a result of the fact that the homogenizing mechanism is assigned a dedicated energy supply, in particular an internal combustion engine, the mechanism or the mixing elements can be operated independently of other devices, such as road pavers or loaders. The homogenizing mechanism is therefore not dependent on the fact that the device which supplies it with road building material has sufficient energy reserves for driving the mechanism and the device itself. Furthermore, the mechanism can be operated independently of the production status of the road covering. The homogenizing mechanism is therefore advantageous, in particular for short-term storage of the road building material, without the latter losing its advantageous properties. 
         [0021]    Furthermore, it is provided in particular that the mechanism can be coupled, in particular can be releasably coupled, to a hopper of a road paver and/or of a loader. For this purpose, the mechanism and/or the road paver or loader are/is assigned coupling elements, such as hooks, eyes and the like. 
         [0022]    The present invention can preferably furthermore provide that at least one mixing element is assigned to the mechanism, which mixing element is preferably drivable in a rotating manner about a shaft parallel to a longitudinal axis and the at least one mixing element has blades arranged radially about the shaft, wherein the shaft is preferably assigned a set of long blades and a set of short blades which are arranged in an alternating sequence along the shaft. The shaft of the mixing element is mounted in the receiving space or in the mechanism in such a manner that said shaft is rotatable and is connected directly to a motor of the mechanism. The blades which are attached to the shaft in a manner pointing radially outwards are, for example, of wing-like design, wherein the wing can be shaped flat, concavely or convexly. Furthermore, it is conceivable that the blades have a “T” shape, wherein the base of the “T” is connected to the shaft. Different blades or different blade combinations can be connected to the shaft depending on the requirements imposed on the material to be mixed or the road covering to be produced. According to the invention, it is provided that the “T”-shaped blades are arranged in an alternating manner with a short base and a long base along the shaft. Furthermore, the blades which are assigned to a common section on the shaft can enclose different angles to one another. The blades are dimensioned in such a manner and the shaft is positioned in such a manner that they cover as large a volume region of the receiving space as possible and, when the mixing element rotates, as large a portion of the road building material as possible is thoroughly mixed or ploughed through. 
         [0023]    It can be provided in a further refinement possibility that the mechanism has two mixing elements, the shafts of which are oriented parallel to each other and which are preferably drivable so as to rotate in opposite directions to each other, wherein the distance between the blades, which rotate in opposite directions about the shaft, of the respective mixing elements is minimized, in particular in that the blades, which rotate in opposite directions to each other, of the respective mixing elements overlap without coming into contact. For example, it is conceivable that a short and a long blade of each shaft always lie opposite each other in such a manner that the mixing elements, inter-engaging in a corresponding manner, thoroughly mix or homogenize the road building material. The mixing elements can be driven at different speeds governed by the situation, but are also driven in a rotating manner independently of one another at different speeds or in different directions. For this purpose, the drive is assigned a corresponding gearing. 
         [0024]    Furthermore, it can preferably be provided that the mechanism has wheels with which the mechanism can be supported on an underlying surface, the wheels are preferably removable from the mechanism and the mechanism can be fastened, in particular releasably, in the hopper. In particular in the case of a mechanism loaded with road building material, it is advantageous if the mechanism is at least partially supported by wheels. The entire weight is thus not loaded on the road paver and does not impair the driving properties thereof. In order to supply the road paver with road building material, the mechanism can be fastened in the hopper. However, it is also conceivable for the homogenizing mechanism to be positioned on the far side of the road paver and to be able to be lowered onto the road paver or into the hopper when required by a lifting mechanism. During this, the road covering is preferably continuously homogenized in the receiving space of the mechanism. The wheels can be coupled to and decoupled from the mechanism depending on the operating mode. 
         [0025]    The present invention can preferably furthermore provide that the at least one opening for feeding the road building material to a further device is closable and at least partially corresponds to an opening in the hopper. In an advantageous exemplary embodiment of the present invention, the mechanism has an opening in a lower side. When the homogenizing mechanism is not located in the hopper of the road paver, but rather is mounted on the far side of the road paver, this opening is closed, and therefore the road building material does not inadvertently pass onto the underlying surface. As soon as the road building material is sufficiently homogenized, this opening is opened such that said road building material is transported on the conveyor of the road paver to the paving screed. 
         [0026]    Furthermore, it can be provided that the mechanism has a cleaning mechanism by means of which the receiving space and the at least one mixing element can be cleaned, and/or in that the mechanism, in particular the receiving space, can be heated by means of the dedicated energy supply, and/or the mechanism, in particular the receiving space, has preferably thermal insulation. The cleaning mechanism cleans the homogenizing mechanism preferably with water or the cleaning liquid. As a result, it can be provided that the mechanism is assigned a plurality of spray nozzles which are connected to a liquid supply system. Furthermore, the receiving space is heated up by heating elements which are supplied with energy by the engine. So that the energy serving for heating the road building material is not lost, the receiving space has thermal insulation. This is advantageous in particular in the event that the homogenizing mechanism is stored away from the road paver. The mechanism can thus be deposited directly onto the road paver when required and the road building material is ready for use. The cleaning mechanism and the spray nozzles serve for acting upon the entire interior of the mechanism with the liquid or a cleaning emulsion. The interior may be cleaned after the mechanism is used. It is conceivable for the cleaning liquid to have an anti-stick agent which is intended to at least partially prevent re-solidification of road building material in the interior of the mechanism. The liquid supply system comprises a tank which is connected directly to the mechanism, preferably is fastened to the mechanism. 
         [0027]    The present invention can preferably furthermore provide that the cleaning mechanism can be operated automatically, in particular depending on the degree of soiling, the filling level of the mechanism with road building material, planned refilling of the mechanism, and/or external conditions, such as temperature and humidity. For this purpose, the invention can make provision for the mechanism to have at least one sensor which determines the degree of soiling of the mechanism. If a soiling threshold value which is to be specified can be determined, the cleaning can take place. The mechanism can also have sensors for ascertaining ambient conditions, such as temperature. Depending on measured values, the cleaning mechanism is automatically controllable via a control mechanism. In addition, the drive of the shafts can be assigned a sensor for determining the load, wherein the mechanism is cleaned depending on the load on the drive. If the load, for example, is high relative to a reference value although there is no road building material in the mechanism, the degree of soiling can be classified as being high. Furthermore, the controller of the cleaning mechanism can be connected to an onboard computer of the loader, and therefore the mechanism is cleaned only between two operations to fill it with new road building material. 
         [0028]    Furthermore, in a particularly advantageous exemplary embodiment of the invention, the at least one mixing element can be exchanged, preferably in that the blades of the at least one mixing element can be exchanged. In particular, the mechanical but also the thermal loading of the blades is very high because of the homogenization. The blades can therefore become worn or functionally incapable. In order to ensure continuous operation of the homogenizing mechanism and therefore little idling time, the blades are interchangeable in groups or individually. Furthermore, the blades can be interchanged individually depending on the requirements imposed on the mixing process, and therefore optimized mixing can take place for every road building material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Preferred exemplary embodiments of the invention are described in more detail below with reference to the drawing, in which: 
           [0030]      FIG. 1  shows a side view of a road paver with a homogenizing mechanism, 
           [0031]      FIG. 2  shows a perspective illustration of the road paver according to  FIG. 1 , 
           [0032]      FIG. 3  shows a top view of the road paver according to  FIG. 1 , 
           [0033]      FIG. 4  shows a front view of the road paver and of the homogenizing mechanism according to  FIG. 1 , and 
           [0034]      FIG. 5  shows a perspective illustration of the homogenizing mechanism. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0035]    The road paver  10  which is illustrated schematically in  FIG. 1  is of self-propelled design. For this purpose, it has a central drive unit  11  which, for example, has an internal combustion engine which, for example, drives hydraulic pumps for supplying hydraulic engines and optionally a generator for generating energy for electric drives. 
         [0036]    The road paver  10  has a running gear  12  which, in the exemplary embodiment shown in  FIG. 1 , is designed as a crawler track, but may also be designed as a wheeled undercarriage or as a different running gear or traveling gear. 
         [0037]    A hopper  14  of tank-like or trough-like design is arranged upstream of the drive unit  11 , as seen in the paving direction  13 . The hopper customarily holds a supply of the road building material, for example asphalt, serving to produce the road covering. A plurality of hoppers  14  may optionally also be provided. The hopper  14  has two flaps  15  which are arranged opposite each other and can be swung up parallel to the paving direction  13 . During the production of the road covering, the two flaps  15  are in a swung-up position, and therefore they enclose an angle, the apex of which coincides with a center axis of the road paver  10 , wherein said apex region is open so that the road building material can slip onto a conveyor belt guided under the flaps  15 . For the refilling of the hopper  14 , the two flaps  15  are pivoted into a horizontal position such that a receiving width of the hopper  14  is maximized. 
         [0038]    By means of conveying members (not illustrated), the road building material from the hopper  14  under the drive unit  11  is transported through the rear end of the road paver  10 , as viewed in the paving direction  13 . The road building material is distributed over the entire working width of the road paver by a spreader screw (not illustrated) arranged behind the running gear  12 . The road building material passes here in front of a paving screed  16  which is hooked on the running gear  12  behind the spreader screw and is movable up and down. 
         [0039]    The road paver  10  is controlled by an operator (not illustrated) from an operating stand  31 . Said operating stand  31  can be designed as a closed or open cab. The operating stand has a driver&#39;s seat (not illustrated) and an operating console. During the process of producing the road covering, the road paver  10  moves in the paving direction  13 . In the process, the road building material is conveyed from the hopper  14  to the spreader screw which spreads the material over the entire laying width, and therefore the road building material can be compacted by the following paving screed  16  to form the road covering. 
         [0040]    In the exemplary embodiment of the present invention that is illustrated in  FIG. 1 , a mechanism  17  for homogenizing road building material is assigned to the swung-open hopper  14 . Said mechanism  17  is of trough-shape design and its area corresponds approximately to the hopper  14 . The mechanism  17  illustrated in  FIG. 2  has a greater height than the hopper  14 . Two mixing elements  19 ,  20  are assigned to a receiving space  18  of the mechanism  17 , which receiving space serves for receiving the road building material. Said mixing elements  19 ,  20  are connected rotatably to the mechanism  17  and serve for mixing or homogenizing the road building material. 
         [0041]    A front  21  of the mechanism  17  is assigned an energy supply  22  for the mechanism  17 , in particular for the mixing elements  19 ,  20  ( FIG. 4 ). Said energy supply  22  may be, for example, an internal combustion engine which drives the mixing elements  19 ,  20 . Said energy supply  22  can be operated independently of the drive unit  11  of the road paver  10 . The mechanism  17  can therefore also be operated independently of the road paver  10 . 
         [0042]    In the case of the exemplary embodiment of the energy supply  22  that is illustrated in  FIG. 2 , the engine is located in a cupboard-like housing  23  which is assigned wheels  25  on a lower side  24 . During the operation of the road paver  10 , said wheels  25  are located on the underlying surface and therefore serve for additionally supporting the mechanism  17 . The wheels  25  can be attached to or removed from the housing  23  or the device  17  depending on the requirements and properties of the road paver  10 . In particular in order to relieve the device  17  of weight, it may be advantageous for the housing  23  to be supported by the additional wheels  25 . 
         [0043]    In order to clean the receiving space  18  of the mechanism  17 , said receiving space is assigned cleaning mechanisms  26  ( FIG. 3 ). Said cleaning mechanisms  26  have, for example, nozzles through which a cleaning liquid, such as, for example, water or an emulsion with an anti-stick component, can be sprayed into the receiving space  18  or onto the mixing elements  19 ,  20 . As a result, after the production of the road covering, the receiving space  18  or the mixing elements  19 ,  20  can be freed from impurities, such as remaining road building material. According to the invention, the cleaning devices  26  can be operated automatically depending on various parameters. For this purpose, the mechanism  17  can be assigned at least one sensor and a control device. 
         [0044]    The mixing elements  19 ,  20  each have a shaft  27 ,  28 , which shafts are oriented parallel to each other and to the paving direction  13 . The shafts  27 ,  28  are assigned a multiplicity of blades  29 , in each case spaced apart radially. The blades illustrated by way of example in  FIG. 3  are of “T”-shaped design. It can be provided according to the invention that the shafts  27 ,  28  are assigned two sets of blades, the “Ts” of which are designed so as to differ in length. Said blades  29  which differ in length are arranged in an alternating manner, as seen in the paving direction  13 , and therefore a long blade  29  is followed by a short blade, etc. Furthermore, the individual blades  29  are arranged on the shafts  27 ,  28  in a slightly rotated manner in relation to the paving direction  13 . The two shafts  27 ,  28  are spaced apart from each other in such a manner that the blades  29  do not touch, but reach as large a portion of the receiving space  18  as possible. 
         [0045]    According to the invention, the shafts  27 ,  28  are driven in such a manner that they rotate in opposite directions to each other. However, it is also possible for the shafts  27 ,  28  to rotate synchronously with respect to each other or at different rotational speeds. 
         [0046]    The individual blades  29  each have a type of sleeve  30  at the transition to the shafts  27 ,  28 . It is provided that the individual blades  29  are connected releasably to the shafts  27 ,  28  such that, in the event of a defective blade  29 , said blade can be interchanged. 
         [0047]    For the production of a road covering, road building material is poured into the receiving space  18  of the mechanism  17  by, for example, a lorry and is then thoroughly mixed or homogenized by the mixing elements  19 ,  20 . Furthermore, the mechanism  17  has heating which is supplied in any case by the energy supply  22 . By means of the homogenization of the road building material by the mixing elements  19 ,  20 , not only is the material therefore blended, but also a homogeneous distribution of temperature is also brought about. 
         [0048]    The lower side of the mechanism  17  is assigned a preferably closable opening. The homogenized road building material passes through this opening to the conveyor of the road paver  10 , with which said road building material is transported to the paving screed  16 . 
         [0049]    According to the invention, it is provided that the mechanism  17  can be operated independently of the road paver  10 . Accordingly, the mechanism  17  can homogenize road building material even when detached from the road paver  10  ( FIG. 5 ). The energy supply  22  which is dedicated to the mechanism  17  serves here for driving the mixing elements  19 ,  20  and for the energy supply of the heating elements (not illustrated). For example, road building material can thus be prepared or homogenized while the road paver  10  is already producing a road covering. When further road building material is required, the mechanism  17  together with the road building material can then be lowered into the hopper  14 . The mechanism  17  according to the invention has proven particularly advantageous in particular because of the increased receiving volume of the mechanism  17  relative to the hopper  14 . 
         [0050]    Even though a road paver  10  is illustrated in  FIGS. 1 to 4  exclusively in combination with the mechanism  17 , the mechanism  17  is equally also usable in combination with loaders. At this juncture, it should be explicitly stressed that the present invention is not intended to be restricted to the exemplary embodiments illustrated, but rather, on the contrary, further embodiments are conceivable. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           10  Road paver 
           11  Drive unit 
           12  Running gear 
           13  Paving mechanism 
           14  Hopper 
           15  Flap 
           16  Paving screed 
           17  Mechanism 
           18  Receiving space 
           19  Mixing element 
           20  Mixing element 
           21  Front 
           22  Energy supply 
           23  Housing 
           24  Lower side 
           25  Wheel 
           26  Cleaning mechanism 
           27  Shaft 
           28  Shaft 
           29  Blade 
           30  Sleeve 
           31  Operating stand