Abstract:
A large round baler includes an expansible baling chamber having an inlet at a forward location thereof and defined in part by a lower run of a flexible, endless component arrangement of an upper conveyor, and by an upper run of a flexible, endless component arrangement of a bottom conveyor. In each of two embodiments, the bottom conveyor includes a moveable roller which operates to selectively deflect the upper run of the bottom conveyor so that it cooperates with a lower run of the upper conveyor so as define a baling chamber having a cross section conducive to starting a bale core at the beginning of the baling process and moveable to a discharge position for allowing a completed bale to roll onto the ground. In the second embodiment, the upper conveyor also includes a moveable roller operates to yieldably resist expansion of the lower run of the upper conveyor.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention pertains to baling chambers of large round balers, and more specifically relates to such chambers as are provided with a bottom conveyor for aiding in the support and discharge of a bale.  
         BACKGROUND OF THE INVENTION  
         [0002]    A round baler known from U.S. Pat. No. 4,208,862 features a baling chamber defined in part by an upper, expansible conveyor, that conforms to the shape of a bale being formed, and a lower conveyor which supports the bale and cooperates with the upper conveyor in discharging the bale. At the beginning of the baling process the baling chamber is of a wedge-shaped cross section of short height and long sides converging to the rear of the baler.  
           [0003]    The patented baling chamber has the drawback of not being constructed so as to reliably start a bale core at the beginning of the baling process.  
         SUMMARY OF THE INVENTION  
         [0004]    According to the present invention, there is provided a round baler baling chamber having an improved conveyor arrangement.  
           [0005]    An object of the invention is to provide a large round baler with a baling chamber including a conveyor arrangement constructed so as to aid in the formation of a bale core at the beginning of the baling process.  
           [0006]    A more specific object of the invention is to provide a large round baler with a baling chamber defined in part by a bottom conveyor including an endless, flexible component arrangement having an run which may be selectively altered in such a way as to cooperate with a lower run of an endless, flexible component arrangement of an upper conveyor in the starting of a bale core.  
           [0007]    Yet a more specific object of the invention is to provide a baling chamber for a large round baler, as defined in the immediately preceding object, wherein a support roller for the upper run of the bottom conveyor is mounted for being moved among a starting position, wherein it alters the configuration of the upper run in such a way that it aids in the starting of a bale core, an intermediate range of positions, wherein it aids in supporting a bale being formed in the baling chamber, and a final position, wherein it configures the upper run for easy discharge of a completed bale.  
           [0008]    Still, another object of the invention, in accordance with a second embodiment, is to provide a large round baler having a baling chamber as defined in one or more of the preceding objects and which includes a further movable roller that supports a section of a crop-engaging lower run of the upper conveyor, this roller being movable between a starting position, wherein in it configures the upper conveyor run so as to cooperate with the bottom conveyor so as to define a chamber cross section that aids in the start of a bale core, and a second position wherein it is withdrawn into the discharge gate so as not to interfere with the discharge of a completed bale.  
           [0009]    These and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a schematic left side view of a large round baler having a baling chamber defined in part by a bottom conveyor constructed in accordance with the principles of the present invention, with a movable roller shown in a raised, bale core starting position.  
         [0011]    [0011]FIG. 2 is a view like FIG. 1, but showing the movable conveyor roller in an intermediate, bale support position.  
         [0012]    [0012]FIG. 3 is a view like FIGS. 1 and 2, but showing the movable conveyor roller in a lowered, bale discharge position.  
         [0013]    [0013]FIG. 4 is a schematic left side view of a large round baler having a baling chamber constructed in accordance with a second embodiment of the invention wherein a bottom conveyor, and an upper conveyor both have movable roller which are each shown in respective bale core starting positions.  
         [0014]    [0014]FIG. 5 is a schematic left side view of the large round baler shown in FIG. 4, but with the movable roller being shown in respective bale discharge positions. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Referring now to FIG. 1, there is shown a large round baler  10  having a front frame  12  and a discharge gate  14 .  
         [0016]    The round baler  10  is used in a conventional manner to pick up mowed forage crops and to press them into round bales of variable size. Fundamentally, however, the invention can also be used for a round baler that features a baling chamber with a size that essentially does not change.  
         [0017]    The frame  12  comprises an axle  16  with wheels  18 , a tongue  20  and side walls  22 , and carries a collector or pick-up  24 , a rotary conveyor  26 , a cutting arrangement  28 , a bottom or floor conveyor  30 , a carrier  32  with rollers  34 , deflection rollers  36 , a tensioning device  38 , and bale-forming, flexible component arrangement  40 . The frame  12  is supported, by the axle  16  and wheels  18 , for being pulled over a field by a tractor (not shown) coupled to the forward end of the tongue  20 . The tongue  20  may be connected to the frame  12  in a rigid, flexible, or adjustable manner. The side walls  22  are attached rigidly to the frame  12  and they limit the sides of a baling chamber  42  for a round bale  44 .  
         [0018]    The collector or pick-up  24  is designed in a conventional manner as a pick-up that may have the same, or a greater, width than the baling chamber  42 . The collector  24  picks up crops from the ground with overshot, guiding prongs  46  and moves the crops along a conveyor surface, that is not described in greater detail, to the cutting arrangement  28 , where it is fed into the baling chamber  42 . The conveyor  26  operates in an undershot manner and is designed as a rotor that helps to feed the material guided from the collector  24  into the cutting arrangement  28 . The conveyor  26  can feature a smooth surface or it can have drivers, prongs, teeth rigs, screws, or the like.  
         [0019]    The cutting arrangement  28  comprises a base  48 , a cover  50 , a rotor  52 , blades  54  and a stripper  56 , like those that are known in the art. The cutting arrangement  28  is not important for the invention, but rather it is only cited as an addition to this embodiment. In particular, the blades  54  can be omitted, so that the rotor  52  acts like a simple conveyor. When the cutting arrangement  28  is present, it is used to reduce material fed from the collector  24 , so that the material can be better packed in the baling chamber  42 . The base  48  extends between the collector  24  and the bottom conveyor  30  and assumes a curvature that essentially follows the radius of the rotor  52 .  
         [0020]    The cover  50  extends with the same curvature between the conveyor  26  and the carrier  32  or a roller  34  arranged at its lower end region. Upstream of the rotor  52 , the base  48  and the cover  50  form a receiving opening and downstream from the rotor, they form an inlet  58  to the baling chamber  42  that is simultaneously limited by the lower roller  34  and the bottom conveyor  30 . As viewed from the side, the baling chamber inlet  58  is located in the first quadrant of the rotor  52  and thus is essentially at the side.  
         [0021]    The rotor  52  features a central pipe  60  and curving drivers  62  set on the central pipe  60 . The central pipe  60  is driven by a drive (not shown) to rotate clockwise, when one looks at the baler from the left side. The drivers  62  are essentially triangular and their tips nearly reach the base  48  and the cover  50 . A total of five rows of drivers  62  are welded onto or screwed into the central pipe  60  in a spiral line, wherein the drivers  62  are separated from each other in the axial direction of the rotor  52 . The diameter of the rotor  52  is a considerable size and takes up approximately 0.6 m.  
         [0022]    The blades  54  are designed in a conventional manner and preferably, they can be locked in various positions and withdrawn if there is an overload. The blades  54  project through not-visible slots in the cover  50  in all, or part, of the intermediate spaces between the drivers  62 . The blades  54  are held by a common, adjustable carrier (not shown), and, in one end position, they can extend up to the inner edge of the cover  50 . As already mentioned, the blades  54  can also be omitted, so that the rotor  52  is not acting for cutting, but rather only as a conveying rotor. The blades  54  are located over the rotor  52  upstream of the inlet  58 .  
         [0023]    The strippers  56  are located downstream of the blades  54  and likewise in the intermediate spaces between the drivers  62 . An upper edge of the driver  62  runs sloping slightly down and slightly curved on the side which faces the discharge gate  14  as the driver  62  sweeps past the inlet  58 . On one side, the strippers  56  border and follow closely the contour of the center pipe  60 , and on the other side, they border the and follow closely the contour of the front of the bottom conveyor  30 . The position of the stripper  56  is chosen so that the round bales  44  can be partially supported on it in the beginning phase of the bale formation and, thus, close the inlet  58  to a certain degree.  
         [0024]    In this embodiment, the bottom or floor conveyor  30  is formed from two stationary rollers  64 , a movable roller  65  and arms  67 , a carrier  69  and an endless, flexible component arrangement  71 . The fixed rollers  64  are respectively rotatably mounted in front and rear end regions of the carrier  69 . In this embodiment, the front roller  64  features a larger diameter than the rear and moveable rollers  64  and  65 , respectively. The movable roller  65  is supported so that it can rotate at the free ends of the vertically pivotable arms  67 . The arms  67  are mounted to the carrier  69  between the fixed front and rear rollers  64  in a support  73  and they are dimensioned such that they can position the roller  65  behind the rear roller  64  when they are in a position tilted completely towards the rear. The support  73  for the arms  67  is located in the space between the fixed rollers  64  and between the upper and lower runs of the flexible component arrangement  71 . The carrier  69  can be pivoted vertically about a pivot axis that coincides with the rotational axis of the front roller  64  that, in turn, is supported in the frame  12  or its side walls  22 . A pair of hydraulic tilt cylinders  92  for the conveyor  30  are respectively mounted between the side walls  22  and the carrier  69  for selectively pivoting the conveyor  30  about the pivot axis defined by the axis of its front roller  64 . The flexible component arrangement  71  is tensioned by the rollers  64  and  65  and bridges the distance between the rollers  64  and  65  in order to realize a more or less closed conveyor surface. The flexible component arrangement  71  can be designed from several belts laid next to each other, a conveyor belt, or a chain drive conveyor. The flexible component arrangement  71  is dimensioned such that its upper run can be deflected. According to the required dimensions of the deflection, each rearward roller  64  can be fixed to move radially in the carrier  69 . The configuration of the bottom or floor conveyor  30  with the flexible component arrangement  71  is selected for this embodiment, but this is not necessary. Instead of this configuration, several rollers  64  and  65  can also be arranged near each other, which as a whole can essentially form a conveyor surface like that also formed by the flexible component arrangement  71  guided over the rollers  64  and  65 . In the position shown in FIG. 1, the bottom conveyor  30  or its carrier  69  essentially assume a horizontal position.  
         [0025]    Each arm  67  can pivot in a vertical plane extending in the driving direction and for this purpose is joined to a crank arm located on an outer surface of the adjacent side wall  22  and coupled to a hydraulic cylinder  94  anchored to the side wall. The pivoting motion is controlled such that at the beginning of the baling process the movable roller  65  assumes a position that is to the left and below that shown in FIG. 1, so that a lower run of the bale-forming, endless flexible component arrangement  40  can extend straight or essentially straight and contact or at least be near the movable roller  65 . In the position shown in FIG. 2, the round bale  44  has achieved its full size. In this situation, the arms  67  are pivoted with the roller  65  backwards into an approximately two o&#39;clock position. In this position, the movable roller  65  is located in the direct vicinity of a lower front deflection roller  82  of the discharge gate  14 , which is described in greater detail below. In this state, the front roller  64  and the movable roller  65  are located essentially at the same height so that the upper run of the flexible component arrangement  71  that extends between them engages the round bale  44  and is deflected downward by its weight so as to define a trough that receives the round bale  44 . The rear roller  64  is located essentially vertically below the front roller  64 . In the position shown in FIG. 3, the round bale  44  is ready to be discharged, with the arms  67  being located in a rearward pivoted location, wherein the movable roller  65  is located behind, and slightly above, the fixed rear roller  64 . In this situation, there results an essentially straight and downward sloping surface of the bottom conveyor  30 , on which the round bale  44  can roll downward and onto the ground when the discharge gate  14  is raised, as shown.  
         [0026]    The motion of the arms  67  can be controlled in a simplified embodiment also by means of springs, which always bias the movable roller  65  towards the inlet  58  and is only moved backwards towards the discharge gate  14  due to the weight of the round bale  44 .  
         [0027]    The bottom conveyor  30  limits the baling chamber  42  in its lower region at one part of its periphery. Preferably, at least one of the rollers  64  is driven.  
         [0028]    The carrier  32  is designed in the form of a bar resistant to bending, and there are two, namely at each side wall  22 , wherein not-shown but adequately reinforcing elements are provided between the two. The carrier  32  can pivot in a vertical plane about a horizontal pivot axis  66  that is perpendicular to the driving direction of the round baler  10 . The pivot axis  66  is located between the ends of the carrier  32 , and in this embodiment approximately at its center, so that it can move like a rocker.  
         [0029]    The rollers  34  can be differentiated into a lower, middle, and an upper roller  34 , when there are three rollers  34 , which, however, is not necessary. The rollers  34  are supported between the two carriers  32  so that they can rotate and extend across the entire width of the baling chamber  42 . The arrangement is chosen such that when the round bale  44  has achieved its full size, the circumference or periphery of the rollers  34  lie on a curved surface that follows the diameter of the round bale  44 . The diameters of the lower and middle rollers  34  are greater than that of the upper roller  34 . The lower roller  34  is always located near the rearward edge of the rotor cover  50 . The rotational axis of the middle roller  34  simultaneously forms the pivot axis  66 , which, however, is not necessary and in other embodiments, this can be solved by other means.  
         [0030]    In particular, the pivot axis  66  can be adjusted downward, upward, forward, or rearward. Between the middle and upper roller  34  there is a gap, through which the bale-forming, endless, flexible component arrangement  40  runs. The lower and middle rollers  34  directly form a part of a front wall of the baling chamber  42  and force is applied to them directly by the material pressed therein.  
         [0031]    The use of the carrier  32  with rollers  34  supported on it is not required for the invention. A single roller or a single deflection roller is sufficient, where this roller guides the bale-forming, flexible component arrangement  40 . In the case of a carrier  32 , it is advantageous if this can be pivoted, but likewise, this is not required.  
         [0032]    A deflection roller  36 , that is preferably driven, extends between the side walls  22  in parallel relationship to the rollers  34  at a location spaced essentially vertically above the carrier  32 .  
         [0033]    The tensioning device  38  comprises a support  70  and an energy storage device  72  that resists movement of a pair of tensioning arms  68  in response to increasing bale size in an essentially known manner. The arms  68  are each formed by a massive steel bar or a steel pipe and, like the carrier  32 , they are respectively located in the region of the side walls  22 . Each arm  68  extends to the rear from the support  70  and terminates outside a rear edge of the adjacent side wall  22 , and is provided with two deflection rollers  36  at the end region remote from the support  70 . These deflection rollers  36  are separated from each other in the radial direction from the support  70 . The arm  68  extends beyond the support  70  at its forward end region and is slightly angled in order to form a lever arm  74 . The support  70  supports the arm  68  at the end region opposite the deflection rollers  36  so that it can pivot vertically. Here, on each side wall  22  there can be a separate support  70  or a support extending between the side walls  22 .  
         [0034]    The energy storage device  72  in this embodiment is formed by a spiral tension spring. Instead of this, a hydraulic cylinder with a compressed air storage device or throttle, another type of spring, a combination of these, or the like could be used. On one end, the energy storage device  72  is attached to the lever arm  74 , and on the other end, it is attached to a holder  76  that contacts the frame  12  or the side wall  22  in a fixed manner. Normally, the energy storage device  72  is at least slightly pre-stressed. However, an embodiment is also conceivable, for which the resistance can be changed by the energy storage device  72 , e.g., by means of a controllable throttle, in order to generate a slightly different compaction over the diameter of the round bale  44 , so that a so-called soft core can be achieved. The direction of action of the energy storage device  72  is chosen so that the arm  68 , with its deflection rollers  36 , is always biased downwardly towards the inlet  58 , i.e., in the sense of a smallest possible baling chamber  42 .  
         [0035]    The bale-forming, flexible component arrangement  40  is preferably formed in this embodiment from several narrow belts that are parallel to each other, like those that are known. The bale-forming flexible component arrangement  40  extending through the frame  12  and the discharge gate  14  is enclosed, i.e., it is endless. Alternatively, each of the frame  12  and discharge gate  14  could be provided with its own bale-forming flexible component arrangement. Due to the pivoting ability of the arm  68  and the carrier  32 , the lower run or region of the bale-forming, flexible component arrangement  40  extending between the upper roller  34  on the carrier  32  and a lower front deflection roller  82  in the discharge gate  14  can be deflected and changed in length. This region represents part of the boundary of the baling chamber  42  and force is applied directly on this region by the material being wound up and compressed in the baling chamber  42 .  
         [0036]    The baling chamber  42  is of variable size and includes the inlet  58  at its periphery, as well as the rollers  34  on the carrier  32 , the lower run of the bale-forming flexible component arrangement  40 , the deflection roller  82  in the discharge gate  14 , and the bottom conveyor  30 . At the front sides, the baling chamber  42  is essentially closed by the side walls  22 .  
         [0037]    The round bale  44  is formed from crops that are wound in the shape of a spiral and that finally reach a size like that shown in FIG. 2. For discharging the round bale  44  from the baling chamber  42 , the discharge gate  14  is pivoted counterclockwise, i.e., lifted, so that the bottom conveyor  30  can roll the round bale  44  onto the ground. The compaction of the round bale  44  is achieved through the tension of the bale-forming flexible component arrangement  40 , which is caused by the energy storage device  72 .  
         [0038]    The discharge gate  14  is connected to the frame  12  so that it can pivot vertically in a support  78 , wherein the pivoting motion is generated by not shown but adequately known hydraulic cylinders. The discharge gate  14  comprises two side walls  80 , several deflection rollers  82 , and a section of the bale-forming flexible component arrangement  40 . The side walls  80  respectively run in the same planes as do the side walls  22  of the frame  12  and cooperate with the side walls  22  to close opposite ends of the baling chamber  42 . Known reinforcing elements that are not shown extend between the side walls  80 . In this embodiment, there are four deflection rollers  82  that are supported in a stationary but rotatable manner in the side walls  80  and extend parallel to the deflection rollers  36  over the entire width of the baling chamber  42 . The deflection rollers  82  are located at the top center, top rear, bottom rear, and at the very bottom front. In a situation according to FIG. 1, the very bottom front deflection roller  82  is in the direct vicinity of the rear roller  64  of the bottom conveyor  30 . The deflection rollers  36 , that are carried by the arms  68 , are respectively provided so as to engage the top of the region of the flexible component arrangement  40  that extends between the upper central and upper rear deflection rollers  82  carried by the discharge gate  14 , and to engage the top of the region of the flexible component arrangement  40  that extends between the upper center deflection roller  82  of the discharge gate  14  and the upper front deflection roller  36  of the frame  12 .  
         [0039]    This results in the following function of the round baler  10  according to FIGS.  1 - 3 .  
         [0040]    In a situation that is not shown, in which each arm  68  is located in its lowest position due to the effect of the energy storage device  72 , the carrier  32  approximately assumes its position shown in FIG. 1, and the lower run of the flexible component arrangement  40  extending between the upper roller  34  on the carrier  32  and the lower front deflection roller  82  in the discharge gate  14  extend essentially in a plane from front top to back at a slope of approximately 20° from horizontal. The hydraulic motors  94  are then in a condition where they act on the arms  67  so as to lift the roller  65  until it contacts the lower run of the bale-forming flexible component arrangement  40  bordering the baling chamber  42  and converts the otherwise long, triangular baling chamber  42  into a small, nearly equal-sided baling chamber  42  that is quickly filled with baling material. In this case, the baling chamber  42  has a cross sectional shape of a nearly equilateral triangle that defines the smallest volume of the baling chamber  42 .  
         [0041]    At the beginning of the baling process, the round baler  10  is moved over a field with crops, e.g., formed into windrows, and the crops are collected from the ground by means of the collector  24  and fed to the cutting arrangement  28 . The rotor  52  guides the material in an overshot manner and, past the blades  54 , if the latter are used, into the baling chamber  42 , wherein it is guided by contact with the lower run of the bale-forming flexible component arrangement  40  and the upper run of the flexible component arrangement  71 . Due to the rotatable support and if necessary the drive of the rollers  64  and of the rollers  34  together with the packing surface of the lower run of the bale-forming flexible component arrangement  40  and the upper run of the flexible component arrangement  71 , a sufficient amount of crops are rotated in the counterclockwise direction, with respect to the view in FIGS.  1 - 3  of the drawing, to form a bale core. In another embodiment, the round bales  44  can also be wound in the clockwise direction.  
         [0042]    With an increasing amount of crops entering the inlet  58 , the round baler  10  achieves the operating state illustrated in FIG. 1, in which the arm  68  is moved slightly upward against the effect of the energy storage device  72 , and thus the lower run of the bale-forming flexible component arrangement  40  is deflected upwards and assumes a truncated roof-like shape. The carrier  32  is pivoted about the pivot axis  66  slightly in the counterclockwise direction, so that its lower roller  34  is moved to the rear. In this situation, the round bale  44  is supported on the front roller  64  of the bottom conveyor  30 , on the strippers  56 , and on the region of the upper run of the flexible component arrangement  71  that extends between the front roller  34  and the movable roller  65 .  
         [0043]    With further feeding of crops, the round bale  44  achieves the size shown in FIG. 2. In this operating state, the arm  68  is pivoted completely upward and the energy storage device  72  is completely tensioned, so that the highest possible compaction is achieved on the peripheral surface of the round bale  44 . Because the upper run of the bottom conveyor  30  cannot be optionally withdrawn, the round bale  44  expands upwardly, so that its peripheral surface presses on the top roller  34  and pivots the carrier  32  in the counterclockwise direction about the pivot axis  66 . Because the pivot axis  66  is located between the ends of the carrier  32 , this pivoting motion causes the lower end region of the carrier  32  with the lower roller  34  to move to the rear and thus to shift the round bale  44  backward so that it is now only supported on the bottom conveyor  30 , with its movable roller  65 , and the lower front deflection roller  82  in the discharge gate  14 . Because the round bale  44  is no longer directly rolling across the inlet  58 , new crops can be fed more easily into the baling chamber  42 , and because the three rollers  34  press on the peripheral surface of the round bale  44  in the region of the carrier  32 , both a good guidance of the round bale  44 , and also a high compaction is achieved.  
         [0044]    As viewed in FIG. 3, the round bale  44  is readied for discharge by lifting the discharge gate  14  in the counterclockwise direction about the coupling  78 , while the carrier  69  is pivoted clockwise, through extension of the hydraulic motors  92 . At the same time, the arm  67  is pivoted to the rear by extension of the hydraulic motors  94  so far that there results an essentially flat top surface of the upper run of the flexible component arrangement  71 , on which the round bale  44  can turn with low friction.  
         [0045]    [0045]FIGS. 4 and 5 show an embodiment of the invention that corresponds to the embodiment according to FIGS.  1 - 3  to a large extent and also features the same function. However, the discharge gate  14  according to the embodiment in FIGS. 4 and 5 features two vertically pivotable arms  86  with a deflection roller  88  supported on them so that it can rotate, and the arms  67  are supported at a point on the carrier  69  that is located noticeably underneath the lower belt run of the flexible component arrangement  71 .  
         [0046]    In the condition of the baler shown in FIG. 5, the moving deflection roller  88  appears at the point of the lower front deflection roller  82  in the discharge gate  14  according to the construction of FIGS.  1 - 3 , and has the lower run of the endless flexible component arrangement  40  engaged with its underside. From this position, the deflection roller  88  can be pivoted forward, while maintaining contact with the lower run, to a starting position forward of the discharge gate  14 , as seen in FIG. 4. The two arms  86  are controlled by hydraulic motors  96 , and/or springs, not shown, such that the moving deflection rollers  88  always keep the baling chamber  42  as small as possible and in this way increases the compaction of the round bale  44 . In this way, the control can be done such that the movable rollers  88  and  65  are arranged and guided nearly next to each other during the baling process, as can be seen in FIG. 4. The arms  86  are suspended in a support  90  on the back side of the discharge gate  14 .  
         [0047]    As can be seen in FIG. 4, the movable roller  65  is mounted to the tops of the arms  67  of the bottom conveyor  30 , while the lower end regions of the arms  67  are respectively pivotally mounted in supports  73  fixed to the carriers  69 , of the fixed front and rear rollers  64  and located approximately at the height of the axle  16 . The length of the arms  67  and the position of the support  73  are dimensioned and located such that the movable roller  65  comes to lie in a position, according to FIG. 5, which is in front of the fixed roller  64 , instead of behind it, like in the embodiment according to FIGS.  1 - 3 , i.e., the movable roller  65  can only move between the two fixed rollers  64 .  
         [0048]    Instead of the attachment of the movable roller  65  on the pivotable arms  67 , it is also possible to attach it in sliding or roller guides, in curved tracks, or on multipart guides.  
         [0049]    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.