Abstract:
A non-stop, large round baler is provided with transversely spaced side walls having peripheries which are not connected to any structure or to the chassis and mounted so as to be adjusted transversely to increase or decrease the width of a bale forming chamber formed between them. Furthermore flexible bale forming elements are trained over rolls carried on the free end of revolving arms mounted outside the side walls, the rolls moving along the periphery of the side walls so as to define between them separate expansible chamber sections permitting one chamber section to begin filling with oncoming crop while the other chamber is being emptied of a completed bale.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a round baler having a set of flexible bale forming elements, useful to form two bale forming chamber sections between side walls and trained over fixed and moveable rolls having at least one conveyor acting with the bale forming elements to cover substantially the circumference of at least one of the bale forming chamber sections and having rotatable arms to carry some of the moveable rolls.  
         BACKGROUND OF THE INVENTION  
         [0002]    EP-A1-0 064 117 discloses a round baler formed as a so-called non-stop baler. This round baler provides an upstream bale chamber and a downstream bale chamber surrounded by an upper and a lower conveyor. The upper conveyor comprises a single set of belts routed side-by-side over a series of fixed and moveable rolls. Three major moveable rolls are carried on a rotatable carrier at three equidistant locations. The spans of the belts between the major rolls are moved with the carrier from the front to the rear and form part of the bale chambers. A gate is provided in which rolls are kept in fixed positions to guide another run of the belts.  
           [0003]    The problem to be solved with respect to this prior art baler is the limitation of the bale diameter by the distance between the major rolls. Another problem is the complexity of this design due to the high number of rolls needed in total. Yet another problem is the need to rotate the carrier inside the bale chamber which requires to double the side walls with discs to support the rotating rolls, as simple arms would interfere with the bale. More uncertain even is the transfer of the bale from one belt span to the next during the process.  
         SUMMARY OF THE INVENTION  
         [0004]    According to the present invention, there is provided an improved arrangement for supporting flexible bale-forming elements of a non-stop, large round baler.  
           [0005]    An object of the invention is to provide an arrangement for supporting flexible bale-forming elements including moveable arms mounted so as to permit relative movement between their respective free ends such as to allow them to reach large bale diameters, at least in the bale chamber concluding the bale cycle, whereas the bale chamber acting as an auxiliary bale chamber may be kept small.  
           [0006]    A more specific object of the invention is to arrange the arms such that the segment of the flexible bale-forming elements that span between adjacent rolls supported by the arms creates a loop which will form a chamber surrounding a substantial portion of the forming bale in a much simpler way than using a multitude of rolls to provide walls of a bale chamber. Furthermore, the density reached with a loop around a bale is much higher than that reached with spans covering the bale only partially. The flexible bale forming elements may consist of belts or chains and slats.  
           [0007]    Yet another object of the invention is to provide a bale chamber defined in part by opposite side walls, the periphery of which is not connected to surrounding structure, such as to allow the moveable rolls to move outside the bale chamber. In such a design the side edges of the belts or other flexible bale forming elements come quite close to the inner face of the side walls and, thus, avoid losses of crop and plugging problems. Furthermore, this feature enables the side walls to be moved laterally, so as to either change or adjust the friction between a bale and the side walls and/or to change the width of a bale formed in the bale chamber.  
           [0008]    Although it is possible to have the arms inside the bale chamber, arms rotating outside the bale chamber are simple to control, avoid friction, (since no crop can squeeze between them and the side wall), and have freedom to move and allow the moveable rolls to be mounted so as to extend beyond the side walls. Arms moving through the space between the side walls would need to be journalled on a bearing outside the periphery of the side walls and should be extendable to a larger extent than arms being journalled within the periphery of the side walls.  
           [0009]    Rolls extending beyond the side walls allow the width of the bale chamber to be selectively increased. Side walls which can be moved laterally, i.e., in the direction of the width of the round baler, enable making bales of different width or the friction between the walls and bale to be reduced when ejecting the bale.  
           [0010]    The size and location of the bale chambers as well as the tension in the bale forming elements can be controlled, if the arms are formed of multiple parts which are adjustable with respect to each other by means of a power actuator. For example, the arms may be lengthened or shortened, tilted, bent or the like, to guide the rolls over which the bale forming elements are trained in a certain pattern.  
           [0011]    One way to adjust the effective length of the arms is to connect its parts like a telescope, e.g., one part may be in the form of a tube, with another part being slidably received in the first part.  
           [0012]    Another way to change the arms is to connect its parts in a joint, which allows the various parts of the arms to assume a position which brings the moveable rolls to the place necessary to create the one or other bale forming chamber.  
           [0013]    Individual drives for each arm allow them to be positioned independently of each other and for electronic controls to be used to determine their position. Such drives may exist in belt or chain drives, in mechanical transmissions, including planetary gears, hydraulic drives, etc., and are controlled depending on the size of the bale, the operation step it currently undergoes, etc.  
           [0014]    While it would be possible to change the position of the arms according to a control device without any feed-back signals, it is more sophisticated to use sensors to constantly compare the relationship between the size of the bale and the position of the arms. This feature allows the bale to be well surrounded by the belts and to eliminate excessive tension in the belts and the parts carrying them.  
           [0015]    One way to make use of the signals emitted by the sensors is to feed them into a hardware electric circuit. More flexibility is obtained though by using a controller based on software, since it is more simple to react to different situations and to activate the power actuators accordingly.  
           [0016]    The number of parts involved is kept low and the relationship between the arms and the sidewalls remains unchanged, if the part connecting the side walls to the chassis and the part bearing the arms is the same, namely an axle. This axle may comprise a strong and rigid tube withstanding the bending and torsion forces applied on it. Since this tube does not obstruct the path in which the arms move, it may have a considerable diameter, like 0.5 m, which is sufficient to support the load.  
           [0017]    Rotating all arms about the same axis avoids a conflict between one arm and the axle on which another arm is journalled or with the other arm itself.  
           [0018]    Filler plates between the lower edge of the side walls are helpful to avoid crop losses and to keep the shape of the bale uniform. Furthermore, they avoid friction of the bale side faces when they slide over the edge of the side wall.  
           [0019]    In order to facilitate the movement of the arms through the gap between the lower edge of the side walls and the bottom conveyor, the filler plates are moveable too. One manner in making the filler plates moveable is to construct them in sections, with certain sections of the filler plates being moveable outwardly and inwardly with respect to the side walls so as to let the rolls and arms pass by. Another way would be to move the filler plate sections along and together with the arms and also to move them from the rear to front in a revolving cycle. Whichever solution is chosen, the position of the arms is used in controlling the position of the filler plates or of its sections.  
           [0020]    Since the shape and the size of the side walls is determined by the location and size of the round bales produced between them, the rolls supported between the free ends of the arms guide the bale forming elements along respective portions of the edges of the side walls. Thus the periphery of the side walls is an excellent place to provide a track for the rolls or the arms. The periphery may by provided with covered or uncovered rails, tracks or the like for that purpose. Alternatively the track, for example a bent, profiled or formed rail, tube, carrier or the like may be attached rigidly to the side wall.  
           [0021]    Three arms are an efficient number to support rolls having flexible bale forming elements extending between them for creating two bale forming loops between them.  
           [0022]    While one roll at the end of each set of arms may be sufficient to carry the flexible elements, such as belts, and while three or more rolls may be used to control the movement of the bale forming elements, two rolls are appropriate to guide and carry the elements, and, depending on the radial distance between them, are helpful to determine the distance of the loops for forming the bale chambers.  
           [0023]    If one bottom conveyor is assigned to each bale forming chamber, i.e., underneath the bale forming elements in the front and the rear, each of them may be designed according to its functions. Whereas a rear bottom conveyor only has to cover the bottom end of the bale forming chamber, the front bottom conveyor has to assist in the start of the bale. For this reason, the bottom conveyor immediately downstream of a pick-up assembly is inclined upwardly and forms a wedge with a span of the bale forming elements.  
           [0024]    One means to provide for the proper tension in the bale forming elements which provides for a good tracking and a high density in the bale is to have at least one moveable roll on an arm applied by a biasing force. The biasing force may come from a spring, a hydraulic circuit, a pressure vessel or the like.  
           [0025]    Such a new round baler is useful also to tie or wrap a produced bale if a wrapping or tying mechanism is provided near the downstream bale chamber to feed net, plastic or twine between the rear bottom conveyor and the bale forming elements.  
           [0026]    The density of the crop may be increased and the quality may be improved if the crop is cut by using a cutting means, since this allows a higher compaction.  
           [0027]    Flexing of the side walls can be limited or decreased if a support is used, which provides for a rigid connection between the chassis and the side walls. Such support can be a link, a hydraulic actuator or the like.  
           [0028]    Another way to avoid an outward bending of the sidewalls under high pressing forces is the use of stops on the rolls, the arms carrying them or a brace bridging the arms, which stops slide or roll along the outside of the side walls and restrain them from bending outwardly.  
           [0029]    One alternative way to control the movement of the rolls on the arms is to use a track, which controls the movement of that part of the arm, which carries the rolls.  
           [0030]    While conventionally the flexible bale forming elements are arranged above a bottom conveyor or above a pick-up assembly, this is not absolutely necessary. It is possible too, to feed a bale forming chamber between bale forming elements also from the top. This would provide for a longer path between the pick-up assembly and the inlet for crop processing, like cutting and adding additives, and it would be easier to carry the weight of the bale. Reference is made also to already existing machines having the feeding on the top.  
           [0031]    Using the existing pick-up assembly to close the bale forming chamber just being fed at the bottom, render another bottom conveyor superfluous. Thus cost savings and a higher reliability may be achieved.  
           [0032]    There are two ways to close the bale forming chamber, which is currently fed, by means of the pick-up assembly. One is to move the inlet of the bale forming chamber to a location above the pick-up assembly. Another is to move the pick-up assembly accordingly. Movement may be accomplished by using hydraulic motors and tracks, links or the like. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    The drawing shows two embodiments of the invention explained in the description below, whereas it is shown in:  
         [0034]    [0034]FIG. 1 is a schematic left side depiction of an empty large round baler constructed in accordance with a first embodiment.  
         [0035]    [0035]FIG. 2 is a view like FIG. 1, but showing a partially filled main bale chamber and adding some drive elements for positioning the arms that support the baleforming belt support arms.  
         [0036]    [0036]FIG. 3 is a view like FIG. 1, but showing an almost full main bale chamber.  
         [0037]    [0037]FIG. 4 is a view like FIG. 1, but showing a completely filled main bale chamber now moved to the rear of the round baler,  
         [0038]    [0038]FIG. 5 is a view like FIG. 1, but showing a filled main bale chamber in the rear and an auxiliary bale chamber in the front.  
         [0039]    [0039]FIG. 6 is a view like FIG. 1, but showing the main bale chamber in an open condition and the auxiliary bale chamber filled and ready to be moved rearwardly.  
         [0040]    [0040]FIG. 7 is a schematic rear view of the round baler of FIG. 1 illustrating the filler plates.  
         [0041]    [0041]FIG. 8 is a schematic left side view of a large round baler according to a second embodiment.  
         [0042]    [0042]FIG. 9 is a schematic rear view of the large round baler of FIG. 8.  
         [0043]    [0043]FIG. 10 is a schematic top view of the large round baler of FIG. 8, illustrating structure for keeping the side walls in place.  
         [0044]    [0044]FIG. 10 a  is a schematic partial top view of the round baler of FIG. 8, but showing another structure for keeping the side walls in place.  
         [0045]    [0045]FIG. 11 is a schematic left side view of a large round baler according to a third embodiment.  
         [0046]    [0046]FIG. 12 is a view like that of FIG. 11, but showing a partly filled main chamber.  
         [0047]    [0047]FIG. 13 is a view like that of FIG. 11, but showing a completely filled main chamber.  
         [0048]    [0048]FIG. 14 is a view like that of FIG. 11, but showing a completely filled main chamber and a partially filed auxiliary chamber.  
         [0049]    [0049]FIG. 15 is a view like that of FIG. 11, but showing a partially filled auxiliary chamber and an opened main chamber. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0050]    A first embodiment of the invention is illustrated in FIGS.  1 - 7  and includes a round baler  10  with a chassis  12 , side walls  14 , an arm-and-roller assembly  16  and an endless, flexible bale forming element  18 .  
         [0051]    The round baler  10  is shown as a pull type round baler, to be coupled to a pulling vehicle, like a tractor, but can be part of a self-propelled vehicle as well. Such a round baler  10  is used to produce bales  20 ,  22  (FIG. 5) of straw, hay, alfalfa, etc., in a main bale forming chamber  24  and an auxiliary chamber  26 , which bales  20  are tied or wrapped before they are ejected and dumped to the ground. This type of a round baler  10  is formed as a so-called non-stop round baler, i.e., the round baler  10  is picking up and baling crop, without interrupting the advancement over the field.  
         [0052]    As can best be seen in FIG. 7, the chassis  12  includes a frame  28  supported on an axle  30 , and defined by opposite vertical side structures  32  supporting a tongue  34  to connect the round baler  10  to a tractor or the like. The axle  30  is equipped with wheels  36  to support the round baler  10  on the ground, whereas the wheels  36  may be single wheels or wheels on a tandem axle (not shown). The opposite side structures  32  may be provided with side shields (not shown) to cover the functional elements of the round baler  10  for security reasons.  
         [0053]    Extending between, and rotatably mounted to, the side structures  32  is a lower front roll  38 , an upper front roll  40 , a moveable roll  42  and an upper rear roll  44 . Also extending between, and supported by, the side structures  32  is a pick-up assembly  46 , a front bottom conveyor  48  and a rear bottom conveyor  50 .  
         [0054]    In side view, the side walls  14  are substantially of a wedge shape with rounded edge portions, whereas their height at the front of the round baler  10  is less than at the rear. The size and form of the side walls  14  is determined by the shape and size of the bales  20 ,  22  formed in the auxiliary and in the main chambers  24 ,  26 . The bottom edge of the side walls  14  is substantially a straight line having a length equal to the sum of a conveying plane of the front and the rear bottom conveyors  48 ,  50  and disposed parallel to the rear bottom conveyor  50 , which is disclosed as being horizontal. According to FIG. 7, the side walls  14  are fixed to the structure  32  in a center area by means of an axle  52 . In order to withstand the pressing forces in the bale chambers  24 ,  26  the side walls  14  are reinforced against bending in a known manner by means of stiffener plates and bars (not shown). The axles  52  may be provided with a hydraulic cylinder or the like to move the side walls  14  laterally over a small distance to decrease the friction between the bales  20 ,  22  and the side walls during ejection of the bale  20  or over bigger distances like 0.2 m to increase the width of the bale chamber  24 ,  26  during the full bale forming process. The diameter and the cross section of each axle  52  depends on the structure of the arm-and-roller-assembly  16 , which is rotating about said axles  52 .  
         [0055]    The arm-and-roller-assembly  16  comprises a first arm  54 , a second arm  56  and a third arm  58 , each provided with a pair of parallel rollers  54   a ,  56   a ,  58   a , respectively. The assembly  16  further comprises a first drive  54   b , a second drive  56   b  and a third drive  58   b  assigned to the respective arms  54  to  58 .  
         [0056]    Each arm  54 - 58  is formed of two parts  60 ,  62  (see arm  58  in FIG. 2, for example), which are moveable with respect to each other and the relative position between which can be adjusted by a motor  64 , which preferably is a hydraulic motor or alternatively an electric motor. According to FIG. 2, the parts are hinged to each other in a joint, the pivot axis of which is parallel to the longitudinal axis of the axle  52 , with the parts  60 ,  62  being of about the same length. In a not shown alternative arrangement, both parts  60 ,  62  are connected to each other in a telescopic fashion, allowing an extension and retraction in a mere radial direction. One first, second and third arm  54 - 58  is provided on each side of the round baler  10  in the space between the side walls  14  and the side structures  32 . The arms  54 - 58  of each set are pivotally connected to a central location of a brace or carrier  65  which rotatably receives the respective rolls  54   a - 58   a  at opposite ends thereof. Preferably the rolls  54   a - 58   a  can assume different positions versus the arms  54 - 58  to follow the periphery of the side walls  14 . The respective inner parts  60  of the arms  54 - 58  are journalled on the axle  52  directly or indirectly for a rotation thereabout. For that purpose each inner part  60  is provided with a wheel  66 , here shown as a belt pulley. According to FIG. 7, all wheels  66  are journalled concentrically, whereas the wheel  66  of the first arm  54  is radial innermost and the wheel  66  of the third arm  58  is the radial outermost.  
         [0057]    Each of the drives  54   b - 58   b  has a drive wheel  68 , which drive wheels  68  can be driven independent of each other by means of a hydraulic motor (not shown) for example, or via a mechanical transmission and clutches. Each drive  54   b - 58   b  also comprises an endless, flexible drive element  70 , here shown as a belt, surrounding the wheel  66  and the drive wheel  68  and being engaged with both. If the wheels  66  and the drive wheels  68  are formed as sprockets, the drive element is a chain; if they are formed as sheaves, the drive element is a belt. Each drive  54   b    58   b  is operated such, that it can bring the respective arm  54 - 58  into a certain position and keep it in said position until a change is necessary. As is apparent from FIGS.  1  to  6 , the arms  54 - 58 , while remaining in the same sequence, rotate about the axle  52  during one full baling cycle, whereas the distance between and the operational length of the individual arms  54 - 58  changes through the cycle. In order to avoid a bending and/or torsion of the assembly consisting of the respective arms  54 - 58  and the braces  65 , a respective drive  54   b - 58   b  is provided preferably on both sides of the round baler  10 .  
         [0058]    The flexible bale-forming element  18  is formed in this embodiment by multiple belts arranged side by side and starting with the belts lower front roll  38  are trained over the rolls  38 ,  40 ,  44 ,  58   a ,  56   a ,  54   a  and  42 . Alternatively, a chain-and-slat-assembly could be used. The flexible bale forming elements  18  are well known and fixed in length and width, although they may lengthen slightly under the tension applied. The number of bale forming elements  18  corresponds to the distance between the side walls  14  and can be varied if said distance is changed. The bias in the bale forming elements  18  is maintained by means of force applied by a spring  72  or the like on the moveable roll  42 . The moveable roll  42  may be carried on a pivotable arm (not shown) or in a sliding carriage (not shown) against the bias of said spring  72 . At least one of the rolls  38 ,  40 ,  44 ,  58   a ,  56   a ,  54   a ,  42  is driven and preferably it is one of the stationary rolls  38 ,  40 ,  44 , whereas rubber sleeves of smaller width and with grooves may be used between the rolls  38 ,  40 ,  44  and the bale forming elements  18  to increase the drive friction.  
         [0059]    While the embodiments shown in the drawings have two rolls  54   a ,  56   a ,  58   a  on each arm, one roll  54   a ,  56   a ,  58   a  may be sufficient. The advantage of having two rolls  54   a ,  56   a ,  58   a  is a better routing of the flexible bale forming elements  18  and the ability to create a bigger distance between the bale chambers  24 ,  26 . Contrary, it is possible to have three rolls  54   a ,  56   a ,  58   a  offset to each other and pressing the flexible bale forming elements  18  onto each other to create some friction. Depending on the travel direction of the flexible bale forming elements  18 , such friction may increase the tension in the bale forming elements downstream of the elements and decrease the friction upstream of elements. This enables the tension in the bale forming elements to be reduced in the auxiliary bale forming chamber  26 , which assists in starting a bale, and to increase the tension of the bale forming elements in the main bale forming chamber  28 , which provides for a higher density of the bale  20 . The friction may be adjusted by means of motors, screws, etc.  
         [0060]    As can best be seen in FIG. 5, the arm-and-roller assembly  16  enables the main and auxiliary bale forming chambers  24  and  26 , respectively, to be formed, with the main bale forming chamber  24  being the rear one, in which the bale  20  is completed. The main bale forming chamber  24  is substantially enclosed by a loop of the flexible bale forming elements  18  formed between the adjacent rolls  58   a  and  56   a  of the third and the second arm  58 ,  56  while the auxiliary bale forming chamber  26  is substantially enclosed by a loop of the flexible bale forming elements  18  formed between the adjacent rolls  56   a  and  54   a  of the second and the first arm  56 ,  54 . The size of the loops depends on the position of the arms  54  to  58 , whereas, within limits, the size of each single loop can be varied by adjusting the position and the length of the involved arms  54 ,  56  or  56 ,  58 . It is visible from FIG. 5 that the loops do not extend beyond the periphery of the side walls  14 . As it is apparent from the sequence given in the order of FIGS.  2  to  4 , each auxiliary bale forming chamber  26  turns into a main bale forming chamber  24  as soon as it is moved far enough to the rear, so that a second loop may be formed above the front bottom conveyor  48 .  
         [0061]    The pick-up assembly  46  is of a conventional design with elastic tines rotating in vertical planes to lift crop from the ground and deliver it rearwardly into a gap between the front bottom conveyor  48  and the bale forming elements  18 . The pick-up assembly  46  may be wider than the distance between the side walls  14  and have converging augers to deliver said crop toward a center area, as it is known in the prior art and, thus, not shown.  
         [0062]    The front bottom conveyor  48  is located between the pick-up assembly  46  and the rear bottom conveyor  50 . It is located underneath the front portion of the side walls  14  and extends over about {fraction (1/3)} of the length of them and is inclined with respect to the rear bottom conveyor  50 . Due to the inclination, a wedge is formed between the top surface of the front bottom conveyor  48  and the underside of the bale forming elements  18  located above the conveyor  48 . This wedge shape facilitates the bale starting process, and the position of the first arm  54  is chosen to provide a trouble free bale start.  
         [0063]    The rear bottom conveyor  50  is immediately behind the front bottom conveyor  48  and extends almost to the rear end of the side walls  14 . While in the embodiment shown, the rear bottom conveyor  50  is oriented more or less parallel to the ground, this is not a must. For example, the rear bottom conveyor  50  may decline to the ground so as to let a finished bale  20  drop only a short distance before it reaches the ground.  
         [0064]    While in the embodiment shown, the front and the rear bottom conveyors  48  and  50  consist of belts, a canvas or a chain-and-slat assembly wound about front and rear rolls, of which at least one is driven, other embodiments like a series of rolls, paddles or the like forming an elongated closed conveying surface underneath the side walls  14  are possible, too. Preferably the bottom conveyors  48 ,  50  are wider than the bale chambers  24 ,  26  or at least as wide as their maximum width. Finally, both bottom conveyors  48 ,  50  may be combined to form a single conveyor.  
         [0065]    Referring to FIG. 7, there can be seen a filler plate assembly  74  provided on each side of the round baler  10  between the lower edge of the side walls  14  and the conveyor plane of the front and the rear bottom conveyor  50  to prevent crop, like leaves or brittle straw to escape from the respective bale forming chamber  24 ,  26  through this gap. Each filler plate assembly  74  comprises a filler plate  76 , which is moveable between a position closing said gap and a position in which it is moved out of the track of the respective rolls  54   a ,  56   a ,  58   a . Movement may be achieved either through slanted surfaces at the front end, so that the approaching roll  54   a ,  56   a ,  58   a  moves the filler plate  76  away, or it may be achieved by an actuator like a motor, a linkage or the like, moving the filler plate  76  in a track or about an axis. Each filler plate  76  may consist of several portions which are moved subsequently away from the gap depending on the position of the respective roll  54   a ,  56   a ,  58   a . Portions of the filler plate  76  may be moved in a cycle along the side walls in order to cover always the gap between the bottom conveyors  48 ,  50  to the side wall. For this purpose one set of portions of the filler plate  76  may be attached to the side wall  14  about a horizontal axis  84  to pivot away, when another portion moves along the side walls  14 .  
         [0066]    The position and the length of the arms  54 - 58  are controlled by means of a control circuit  78  having a controller  80  and sensors  82  and acting on the drives  54   b ,  56   b ,  58   b  and the motors  64 .  
         [0067]    The controller  80  is preferably in the form of a software operated computer located on the round baler  10  or on the pulling vehicle and is producing output signals according to a given program.  
         [0068]    The sensors  82  may be provided to measure the position and radial extension of each arm  54 - 58 . Other values may be gathered as well, like the condition and amount of the crop, the position of the moveable roll  42 , the position of the round baler  10  on the field, the status of the tying or wrapping cycle, the diameter of the bales on each side, etc.  
         [0069]    The output signals generated by the controller  80  provide for a movement of the arms  54 - 58  and their parts  60 ,  62  such, that the rollers  54   a - 58   a  at their end follow the sequence given in FIGS.  1  to  6 .  
         [0070]    While it is not shown in the drawing, a net wrap or tying mechanism may be provided at the open side of the main bale forming chamber  24  and in the interface area of between the bale forming elements  18  and the rear bottom conveyor  50 .  
       Operation  
       [0071]    Empty Bale Chambers—FIG. 1:  
         [0072]    All arms  54 - 58  are in a lower position and the bale forming elements  18  extend over them to form sort of a shallow pan in which a front section forms a wedge with the upper surface of the front bottom conveyor  48 . In this stage, the moveable roll  42  is in an upper position and the spring  72  is under little bias. The bale forming elements  18  do not provide a loop between the rolls  54   a ,  56   a  of the first and the second arm  54 ,  56  but a straight span.  
         [0073]    Auxiliary Bale Chamber gets Filled—FIG. 2:  
         [0074]    Due to the crop fed by the pick-up assembly  46  and pushed upwardly against the span of the bale forming elements  18  between the rolls  54   a  and  56   a  of the first and the second arm  54 ,  56 , said span is deflected upwardly to create a small loop in which crop is accumulated and formed to a cylindrical bale  22 . The moveable roll  42  is moved out of its home position slightly. The first arm  54  is moved towards the second arm  56  to better close the auxiliary bale chamber  26  in its bottom area. The arms  56  and  58  are kept in their initial positions since the drives  56   b  and  58   b  are stopped. The rolls  54   a ,  56   a  are substantially in line with the lower edge of the side walls  14 , while the rolls  58   a  follow the rounded corner at the end of the lower edge of the side walls  14 .  
         [0075]    Start of the Transition Stage from the Auxiliary Bale Chamber  26  to the Main Bale Chamber  24 —FIG. 3:  
         [0076]    All arms  54 - 58  are moved counterclockwise, as seen in the FIGS.  1 - 6 . Thus the rolls  54   a  of each first arm  54  come close to the rear bottom conveyor  50  but still allow crop to be fed into the auxiliary bale chamber  26 , the rolls  56   a  of the second arm  56  move to a position located above the rear half of the rear bottom conveyor  50  and the rolls  58   a  of the third arm  58  are moved to a position in which they are no longer in engagement with the bale forming elements  18 . Preferably the rolls  58   a  assume a position close to the moveable roll  42 . The rolls  54   a ,  56   a  are substantially in line with the lower edge of the side walls  14 . The loop and the bale  22  are bigger than the loop and bale shown in FIG. 2. Main bale forming chamber  24  is filled completely—FIG. 4:  
         [0077]    The position of the arms  54 - 58  in FIG. 4 is substantially the same as in FIG. 1, however the third arm  58  is now where the first arm  54  was, the second arm  56  is where the third arm  58  was and the first arm  54  is where the second arm  56  was. The bale  20  reached its full diameter and is ready to be tied with twine, plastic or net. The wedge shaped space underneath the span between the rolls  58   a  and  54   a  of the third and first arms  58 ,  54  and above the front bottom conveyor  48  is ready to receive crop and to start rolling a new bale  22 . The moveable roll  42  is moved further against the bias of the spring  72 .  
         [0078]    A Bale  22  is Formed in the Auxiliary Bale Chamber  26 , while a Bale  20  is Still in the Main Bale Forming Chamber  24 —FIG. 5:  
         [0079]    While the first and the second arms  54 ,  56  remained in their positions, the third arm  58  has been lowered and approaches the front bottom conveyor  48 , but still leaves an inlet for the crop to be baled. In the meantime the bale  20  in the main bale forming chamber  24  is wrapped or tied.  
         [0080]    The Bale  20  is Ejected from the Main Bale Forming Chamber  24 , while the Bale  22  in the Auxiliary Bale Chamber  26  Grows—FIG. 6:  
         [0081]    The third and the first arms  58  and  54  remained in their positions, while the second arm  56  is lifted to open the loop of the main bale forming chamber  24  and create a straight span between the rolls  54   a  of the first arm  54  near the rear bottom conveyor  50  and the upper rear roller  44 . Due to this action the bale  20  is ejected rearwardly and dumped onto the ground. During this ejection, crop is fed continuously to the auxiliary bale forming chamber  26  to increase the diameter of the bale  22  therein. The moveable roll  42  moves back to its initial position, and after the bale  20  is ejected, the second arm  56  is lowered to the position of the first arm  54  as shown in FIG. 2.  
         [0082]    Whenever the rolls  54   a - 58   a  are moved through the gap between the lower edge of the side walls  14  and the top surface of the rear bottom conveyor  50 , the filler plates  76  are moved away to free the track.  
         [0083]    FIGS.  8  to  10  show an alternative embodiment of the round baler, which conceptionally is the same as the one shown in FIGS.  1  to  7 , but there are differences in the structure and control of the arms  54 ,  56 ,  58  as well as in the presence of a support  86  for each of the side walls  14 .  
         [0084]    According to FIG. 8 a track  88  is provided in a vertical plane, with this track  88  being almost a mirror image of the contour of the side walls  14 . The shape of the track  88  is chosen such that the rolls  54   a ,  56   a ,  58   a  follow substantially the contour of the side walls  14  during the rotation of arms  54 ′,  56 ′,  58 ′. The track  88  may be formed of a rail with the cross section of a “U”. The tracks  88  are illustrated fixed to the structure  32 , but may instead be fixed to the side walls  14 .  
         [0085]    The arms  54 ′,  56 ′,  58 ′ are each again formed of inner and outer parts  60 ′,  62 ′, which are pivotally connected to each other. Each of the outer parts  62 ′ at one end carries the rolls  54   a ,  56   a ,  58   a  and is provided at its other end with a trunnion  90 , which is received in said track  88 .  
         [0086]    The support  86  may comprise a hydraulic cylinder or the like fixed to the structure  32  and being moveable towards and away from the side walls  14 . In a retracted position, sufficient space is provided between the support  86  and the adjacent side wall  14  to let the arms  54 ′,  56 ′,  58 ′ pass therethrough, when the bale gets ejected. In an extended position, the support  86 , e.g., a piston of a hydraulic cylinder assembly, abuts the outer face of the side walls  14  and restrains the side walls  14  from bending outwardly. According to FIGS. 8 and 10, the support  86  is provided only at the rear end of the side walls  14 , since high bending forces may be expected there only, whereas in the area of the auxiliary bale forming chamber  26  the side walls  14  should be stiff enough to withstand the forces inside said bale forming chamber  26 . Nevertheless supports  86  may be provided at various places of the side walls  14 .  
         [0087]    According to a not shown alternative to restrain the side walls  14  from bending outwardly, each brace  65  may be provided with stops, possibly carrying rolls, sliding along the outer face of the side walls  14 .  
         [0088]    The third embodiment illustrated in FIGS.  11  to  15  uses the same concept, i.e., the arm-and-roller assembly  16  as the first embodiment, but is different as concerns the feeding of the crop and the way the bale chambers  24 ,  26  are closed in a bottom area.  
         [0089]    Specifically, in the third embodiment, when only one bale is present, like is illustrated in FIG. 3 of the first embodiment, the adjacent arms  54 ,  56 , with respective rollers  54   a ,  56   a , respectively extend further to the rear and to the front than the arms  54 ,  56  in the other embodiments, so that the rollers  54   a ,  56   a , are closer to each other, which enables them to cover the bottom of the main bale forming chamber  26  so far, that a bale formed therein is carried just by the rolls  54   a ,  56   a  of the first and second arm  54 ,  56 , as viewed in FIG. 12. Basically, in the third embodiment, the rolls  54   a ,  56   b ,  58   b  respectively carried by the leading and trailing ones of the arms  54 ,  56  and  58 , are being used in forming any given bale chamber and are disposed closer together so that the bottom conveyors  48  and  50  may be eliminated when used together with a moveable pick-up assembly  46  as described below.  
         [0090]    The situation shown in FIG. 11 corresponds to that in FIG. 1, that in FIG. 13 to FIG. 4, that in FIG. 14 to FIG. 5 and that of FIG. 15 to FIG. 6.  
         [0091]    Furthermore, the pick-up assembly  46  is carried in rails  92  attached to the structure  32  and extending in the space between the wheels  35 . The position of the pick-up assembly  46  along the longitudinal axis of the round baler  10  is controlled by non-shown hydraulic motors. Linear hydraulic motors could move the pick-up assembly  46  on gliders or rolls in the rails  92 , or a gear wheel of a rotating hydraulic motor could mesh with a tooth bar in the rails  92 .  
         [0092]    According to FIG. 12 in comparison with FIGS.  11  to  15 , the pick-up assembly may also be tilted about a horizontal axis in order to fit under the rollers  56   a  of the second arm  56 , when these are moved close to the rollers  54   a  of the first arm  54  in order to close the main bale forming chamber  24  in its bottom area. Tilting the pick-up assembly may be achieved by guide tracks or adjusting means, like a hydraulic motor and a respective control device.  
         [0093]    The pick-up assembly  46  may include a support surface  96 , located behind a reel or picking unit  94 , on which crop is sliding to be engaged by a span of the bale forming elements  18  to become wedged and rolled after that.  
         [0094]    The control of the pick-up assembly  46  is such that the pick-up assembly  46  constantly moves with the bale chamber to be fed with crop from the front to the rear, as illustrated in FIGS.  11  to  15 . As soon as the main bale forming chamber  24  is filled and the bale therein is ready to be wrapped or tied, the pick-up assembly  46  moves to the front to feed the auxiliary bale forming chamber  26 , whereas the bale in the main bale forming chamber  24  is kept in latter by the rollers  54   a  and  56   a  (FIG. 14).  
         [0095]    Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.