Abstract:
A double knotting method and apparatus capable of producing two successive knots in a pair of strands during one full operating cycle of a tying mechanism. The tying mechanism is comprised of a twine holder for maintaining a pair of strands in a suitable position, a cutter that co-operates with the twine holder for severing the strands during formation of successive knots, and a release mechanism for releasing the pair of strands from the twine holder before frill successive knot completion. The method and apparatus avoid twine tail formation.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to agricultural balers and, more particularly, to a baler for forming rectangular bales having a bale knotting system using twine to bind the bales. 
   Rectangular bales conventionally are able to maintain their shape by means of a series of parallel extending twine loops, provided lengthways around the bales. Agricultural balers, utilizing automatic knotters by which two conventional knots are made on every loop for binding a bale, have been available for many years. U.S. Pat. No. 4,142,746, for example, discloses a tying mechanism of the conventional double knotter type. Such a tying mechanism is a complex gathering of elements such as a bill hook for forming the knot, a holder in combination with a retainer for retaining the strands when forming the knot and an arm with an integrated cutter for stripping the formed knot from the bill hook in combination with the separation of the knot from the retained strands. When a bale reaches its desired length, a knot tying cycle is initiated. During this tying cycle, two knots are formed, the first knot for closing the loop of the finished bale and the second knot for starting the loop for the next bale. 
   In use, such conventional knotters, while being effective in binding bales with twine, result in small pieces of twine, commonly known as twine tails, being wasted after each knotting operation. These twine tails are obtained after the second knot is formed and stripped of the bill hook by a moving stripper arm. In conventional knotters, a stripper arm with an integrated cutter is used to strip the knot from the billhook. At the same time, the cutter will cut the strands that are retained by the holder. In contrast with the forming of the second knot, no twine tails will be obtained when forming the first knot, since the strands are at that point still retained by the holder and needed for forming the second knot. The first knot is merely cut loose from the strands and dropped onto the finished bale. 
   Although the amount of twine wasted is not great, as the twine tails are approximately only 3 to 5 cm long, they may build up in the vicinity of the knotter and ultimately cause knotter-tying problems. In some situations the twine tails are removed from the baler when the formed bale is pushed out of the baler, then the twine tails drop on the field where they may cause or contribute to environmental pollution. Indeed, nowadays farmers often use synthetic twine instead of natural fibers. Unlike natural fibers, synthetic twine will not be broken down by atmospheric influences, and therefore, the synthetic twine tails remains longer on the field and may be picked up the next harvesting season by a baler. Eventually, the twine tails will end up in the entrails of life-stock, where they may cause digesting problems or even poisoning as a result of the chemical coloring agents contained therein. Some crops that are used for industrial processes must be prevented from being polluted with synthetic twine tails lest the harvested bale would be worthless and could not be used for further processing. 
   To attenuate the above disadvantages of the presence of twine tails, U.S. Pat. No. 4,805,391 discloses a system to collect the twine tails. A suction fan, connected on one side by hoses to intake units, and on the other side to a container, conveys twine tails from the knotters to the container. Such a collecting system suffers from the disadvantage that sometimes twine tails escape the action of the fan because insufficient suction power is available. The above described problems of twine tails ending up on the field or hampering the operation of the knotter system, thus still remain. Another disadvantage of this system is the necessity of providing an extra device that moreover needs to be powered to collect the twine tails. Since baler knotters are very complex devices, with a high number of elements rotating and moving in different planes, there is little or no space available for such a device in the area of the knotter. 
   Apart from double knotter systems forming two knots on a single loop, it has been known for many years how to close a loop around a finished bale with a single knot. The biggest disadvantage of a loop formed with one knot at the end of the baling process is that relatively high forces are applied to the twine when the bale is formed. Single knotter systems indeed require the twine to be pulled through the baling chamber and around the formed bale in order to be able to close the loop. The higher forces on the twine increase the danger of twine failure or the occurrence of misshapen knots. 
   On the other hand, single knotter systems have the advantage that various types of knotters may be employed, one of which being the conventional knotter already referred to in connection with the double knotter system and producing the twine tails as already explained. Moreover, another type of knotter suitable for a single knotter system is the so-called loop-knotter, producing a small loop on top of the knot. Since loop-knotters operate according to a tying principle which is different from conventional knotters, no twine tails are generated during formation of a knot. The positioning of a loop-knotter relative to the formed bale is such that the bale will pull the formed knot from the bill hook when the knot is made, cutting the formed knot loose from the remaining strand. The retained strand is then used for forming the next loop around the next forming bale. 
   To avoid the formation of twine tails, loop knotters unfortunately cannot readily replace the conventional knotters of a double knotter system, as the operating principle of a double knotter system cannot merely be regarded as a duplication of a single knotter system. When the two knots are formed with a conventional knotter, the bale in the baling chamber remains stationary. This means that no pulling action from the formed bale on the knot can be achieved. So pulling the knot from the bill hook as is done with a single loop-knotter is not possible. 
   SUMMARY OF THE INVENTION 
   Thus, it is a primary object of the present invention to provide a tying mechanism in the form of a double knotter system solving the above described problems by not producing any twine tails at all. 
   It is another object of the present invention to provide a double knotter system for an agricultural baler. 
   Another object of the present invention is to provide a double knotter system that is durable of construction, relatively easy to manufacture and assemble, and reliable in operation. 
   These and other objects are attained by providing a tying mechanism for an agricultural baler, operable to produce two successive knots in a pair of twine strands during one full operating cycle of the tying mechanism. No twine tails will be formed, preventing knotter problems occurring during the baling process. Also environmental pollution will be prevented since no twine tails will be removed from the baler. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a fragmentary, side elevational view of a baler having a double knotter tying mechanism; 
       FIG. 2  is a diagrammatic view of a complete and a partial double-knotted loop as known from the prior art; 
       FIG. 3  is a diagrammatic view of a complete and a partial double-knotted loop without the forming of twine tails  62 ′ and  64 ′ as seen on  FIG. 2 ; 
       FIG. 4  is an enlarged, fragmentary, side elevational view of the knotter, needle and associated mechanism in mid cycle; 
       FIG. 5  is a fragmentary, plan view taken substantially along line  4 - 4  of  FIG. 4 ; 
       FIG. 6  is a fragmentary, front perspective view of the knotter with strands of twine draped across the bill hook and held by retaining discs in readiness of preparing a knot; 
       FIG. 7  is a fragmentary, elevational view of cams on a drive shaft of the knotter for operating a slack take-up arm and a twine finger; 
       FIGS. 8 to 17  are fragmentary, schematic views illustrating the successive steps of a double-knotting operation; 
       FIG. 18  is an enlarged, front elevational view of the tip of a needle which presents the strands to the knotter, illustrating details of the construction thereof; and 
       FIG. 19  is an enlarged view of the bill hook which forms the knot by turning around its lengthways axis, illustrating details of construction thereof. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In the description which follows and in certain passages already set forth, the principles of the present invention will be described in terms of “twine” and “knots” formed in such twine. However, it is to be recognized that such principles extend to wire and twisted junctions of wire as well as twine and knots. 
   Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art, and they will not therefore be discussed in significant detail. Also, any reference herein to the terms “left” or “right” are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application of any element may already by widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. 
   The baler  20  illustrated in  FIG. 1  has a rectangular bale case  22  that is supported by ground wheels  24 . The bale case  22  defines a bale chamber  26  wherein material is pushed though a curved duct  28 . A plunger  30  reciprocates within the bale case  22  to intermittently pack fresh charges of material from the duct  28  rearwardly in the chamber  26  in the direction of the arrow  32 . When the bales reaches a predetermined size (this is determined by an appropriate bale length sensor (not shown)), a trigger  34  is pulled by a rod  36 . This rod  36  engages a dog clutch  38 , the clutch  38  in turn being connected to a tying mechanism and a set of needles  42 . As will be appreciated, the tying mechanism comprises a set of individual knotters  40  provided crosswise on top of the bale chamber  26  at spaced intervals. Each knotter  40  has an associated needle  42  for assisting in forming an individual loop around a finished bale. When the bales needs tying, the dog clutch  38  connects the knotter  40  and their needles  42  via a drive chain  44  to a source of driving power to initiate the tying operation. As the individual knotters  40  all operate in an identical manner, it suffices to describe the present invention in relation to only one such knotter  40 . 
   The needle  42  is swingably mounted on the bale case  22  by a pivot  46  and is swung back and forth across the bale chamber  26  by a linkage  48 , which is activated by the clutch  38 . The needle  42  has an “at-home” or rest position fully below the bale case  22  as illustrated in  FIG. 1  and a “full-throw” position extending completely across the bale case  22  as illustrated, for example, in  FIG. 9 . As illustrated perhaps most clearly in  FIGS. 4 and 18 , the tip  50  of needle  42  has an eyelet  52  defined therein by the opposed furcations  54  and  56  of the bifurcated tip  50  in conjunction with a pair of longitudinally spaced, transversely extending rollers  58  and  60 . It will be noted that the roller  58  is positioned inwardly from the outer extremity of the tip  50 , while the roller  60  is positioned outwardly from the roller  58  more closely adjacent this extremity. Even so, the roller  60  is positioned a short distance inwardly from the outer extremity of the tip  50 , and both of the rollers  58  and  60  may be tapered toward their mid points, comparable to a diabolo, so as to provide secure seats for the tying strands. 
     FIG. 2  shows the binding loop as already known for many years in the prior art. It is also shown in  FIG. 2  that twine tails  62 ′ and  64 ′ are obtained between the last knot  70  of a first bale and the first knot  68   a  of a next bale. As clearly seen in  FIG. 2 , both knots  70  and  68   a  are identical to each other and are so-called conventional knots. 
   In contrast therewith,  FIG. 3  shows the binding loop without twine tails  62 ′ and  64 ′, as obtained by the present invention. In a finished bale, and still comparable to the prior art, the loop  62  is made from two strands of binding material, i.e., one strand  64  along the top side of the bale and a second strand  66  along the bottom side of the bale and its two opposite, vertical ends. The strands  64  and  66  together form the continuous loop  62 . Together, they fully circumscribe the bale and are circumferential complements of one another. However, in contrast with the prior art, the first knot  68  of a bale according to the present invention, is a so called loop-knot. This means that the ends of the strands  64  and  66  of the knot  68  are released from a retained position so they can be pulled back by the movement of an arm  88  (to be described further) to form a small loop on top of the knot. The knot  68  itself, thus holds the ends of the strands  64  and  66 , united with the knot  68  in contrast with a conventional knot in which the ends are cut off by a cutter  94  only a short distance from the knot. These ends are then pulled completely through the formed knot, thus forming a conventional knot as known for many years in the prior art (to be described later). As such, twine ends  62 ′ and  64 ′ are obtained, since these twine ends  62 ′ and  64 ′ are retained by the holder  86  when the cutter  94  passes. The two knots  68  and  70  appear in the loop  62  at those locations where the strands  64  and  66  are substantially end-to-end. This is typically in the area of the top corners of the bale. 
   With reference to  FIG. 3 , to the left of loop  62  is a partial loop  62   a  which is in the process of being formed. The top strand  64   a  emanates from a source of twine supply  72 , while the bottom strand  66   a  emanates from an entirely separate, second source of twine supply  74 . At the particular point in the sequence chosen for illustration, the knot  68   a  is in existence, and the bale is approaching that length where the needle  42  is ready to swing into operation and present the strands  64   a  and  66   a  to the knotter  40  to complete the first knot  70   a  (not shown in  FIG. 3 ). 
   With this short explanation in mind, the details of the embodiment according to the present invention and as illustrated primarily in  FIGS. 4 ,  5 ,  6  and  7  will now be described. The knotter  40  is identical in many respects to a “Deering” type knotter available from P. D. Rasspe Sohne, Hamburg, Germany. That is to say, the components of the knotter  40  which co-operate to form each of the knots of a bale may have a great resemblance to those in a unit provided by the Rasspe Company. 
   As such, the knotter  40  of  FIG. 4  comprises a generally circular element  76  that is secured to a drive shaft  78  for rotation with the latter through one full revolution when the clutch  38  is engaged. The shaft  78  is supported by a forwardly inclined frame  80  attached to the top of the bale case  22 , and the frame  80  also supports the knotter components for forming the knots in response to rotation of the element  76 . 
   Briefly, such components include a rotary bill hook member  82 , supported by the frame  80  for rotation about an inclined axis  84 ; a multi-disc holder  86  rearwardly of and adjacent to the bill hook  82  for holding strands  64   a  and  66   a  in position for engagement by the bill hook  82  during rotation of the latter; and means for releasing the connected strands from the holder  86  in the form of an arm  88  pivotally attached to the frame  80  by a bolt  90 . It is to be noted that the strands  64   a  and  66   a  are held between notches in the rotating multi-disc holder  86  and a retainer  220 . The tensioning force of this retainer  220  to the holder  86  can be adjusted manually by changing the tension of a leaf-spring  200  when a bolt  210  is loosened or tightened. The lower end of the arm  88  is forked, defining a crotch  92  that opens away from the holder  86  beneath the bill hook  82 . The crotch  92  carries a cutter  94  between the bill hook  82  and the holder  86  for severing the strands  64   a  and  66   a  in response to swinging movement of the arm  88  in the proper direction. Such movement of the arm  88  to operate the cutter  94  also serves to bring the proximal areas of the crotch  92  in engagement with a knot formed on the bill hook  82  for stripping such knot off of the bill hook  82 . 
   In order to transmit driving power from the element  76  to the bill hook  82 , the latter is provided with a gear  96  which is disposed for meshing engagement with a pair of circumferentially spaced gear stretches  98  and  100  on the element  76 . Similarly, driving power is transmitted to the discs of the holder  86  through a worm gear drive  102  and a bevel gear  104  in position for sequential meshing engagement with a pair of circumferentially spaced gear sections  106  and  108  on the element  76 . 
   In contrast with a typical “Deering” type knotter, a supplementary gear section  109  is provided after gear section  108  ( FIG. 4 ) for a purpose to be described further on. Power to swing the arm  88  about the pivot bolt  90  is obtained through a cam follower  110  at the upper end of the arm  88  beyond the pivot bolt  90  which is disposed within a cam track  112  on the element  76 . A pair of circumferentially spaced cam shoulders  114  and  116  in the track  112  are positioned to sequentially engage the follower  110  to operate the latter. 
   A finger  118  is located below the bill hook  82  and the crotch  92  of the knotter  40  and is mounted on an upright pivot  120  for lateral swinging movement between a standby position illustrated in  FIGS. 4 and 5  and a full-throw, laterally extended position somewhat beyond that illustrated in  FIG. 6 . An operating link  122  attached at one end to the finger  118  and at the opposite end to a crank  124  serves to effect swinging of the finger  118 . The crank  124  is in turn fixed to a transversely extending shaft  126  that extends to a point behind the element  76  where it carries a second crank  128  as illustrated in  FIG. 7 . The crank  128  is biased upwardly in a counter-clockwise direction by a coil spring  130  and carries a cam follower  132  at its outermost end. The follower  132  is in position for operating engagement with a double-lobed cam  134  fixed to the shaft  78  for rotation therewith, its lobes  136  and  138  being circumferentially spaced apart in accordance with the desired timed relationship between the finger  118  and the knot-forming components of the knotter  40 . 
   Also mounted on the shaft  78  with the cam  134  is a second cam  140  having a peripheral land stretch  142  over approximately 180° of its circumference and a peripheral valley stretch  144  over the remaining approximately 180° of its circumference. Such stretches  142  and  144  are disposed for operating engagement with a cam roller  146  located at the outer end of a lever  148  that is fixed at its inner end to a transverse shaft  150 . The lever  148 , and hence the shaft  150 , are biased in a counter-clockwise direction viewing  FIG. 7  by a coil spring  152 . The shaft  150  extends back out to the opposite side of the element  76  parallel with the shafts  78  and  126  to a point substantially in fore-and-aft alignment with the bill hook  82 . At that location, the shaft  150  fixedly carries a rearwardly extending slack take-up device  154 . The device  154  carries a pair of spaced rollers  156  and  158  at its rearmost end around which the strand  64   a  is entrained as illustrated in  FIG. 4 . A length of the strand  64   a  is also looped upwardly around another roller  160  disposed above the device  154  and carried by the knotter frame  80  adjacent the drive shaft  78 . 
   The strand  64   a  may be clamped between a pair of opposed plates  162  and  164  ( FIG. 4 ) of a tensioning unit  166 . The force with which the plates  162  and  164  clamp the strand  64   a  may be controlled by a wing nut  168  operating against a spring  170  that in turn presses against the movable plate  164 . A tensioning unit similar to unit  166  may also be provided for the strand  66   a , although such additional unit is not illustrated. 
   The condition of the partial loop  62   a  in  FIG. 3 , and that of the knotter  40  and the needle  42 , corresponds substantially with conditions illustrated in  FIGS. 4 ,  5  and  8 , with the exception that in  FIG. 3 , the needle  42  is still in its home position. At this point in the bale forming operation, the bale has reached its desired length and it is time to complete the loop around the bale and make the second knot in the loop. It is remarked that at this specific instance, the strand  64   a  stretches along the top of the bale directly beneath the crotch  92  of the arm  88  but, at least for all effective purposes, is out of contact with the knotter  40 . 
   As illustrated in  FIG. 8 , as the needle  42  swings upwardly toward the knotter  40 , it carries with it the strand  66   a  as the latter is paid out by source  74 . Note that because the strand  66   a  is threaded through the eyelet  52  of needle  42 , a length of that strand on the twine source side of the needle  42  is also carried upwardly toward the knotter  40 , such extra length being hereinafter denoted  66   b.    
   While the needle  42  approaches the knotter  40 , no additional length of the strand  64   a  is pulled from the source  72 . Even as the trip of the needle  42 , and more particularly, the roller  60 , snares the strand  64   a  as illustrated in  FIG. 9  and presents strands  64   a  and  66   a  in unison to the knotter  40 , still no additional length of the strand  64   a  is pulled from source  72  because the device  154  rocks upwardly in a counter-clockwise direction to provide the slack necessary in the strand  64   a  to accommodate the needle movement. In presenting the strands  64   a  and  66   a , the needle actually drapes the strands across the bill hook  82  and thence into awaiting notches of the holder  86 , whereupon rotation of co-operating discs in the latter, in combination with a pressing retainer  220 , serve to firmly grip the strands and prevent their escape as the bill hook  82  begins its rotation as illustrated in  FIG. 10 . When the needle  42  delivers the strands  64  and  66  to the holder  86 , the holder  86  rotates in such a manner that the strands  64  and  66  are retained twice in different notches in the holder  86  ( FIG. 12 ). By doing so, two knots  70   a  and  68   b  can be formed during one knotting cycle as will be explained further, whereby the cutter  94  severs the strands  64   a  and  66   a  from the strands  64   b  and  66   b  after the first knot  70  is formed, and thus separating the two loops  62   a  and  62   b  (not shown) from each other. The adjustable leaf-spring  200  pushes against the retainer  220 , thus co-operating with the discs in the holder  86  to retain the strands. 
   When starting the formation of the first knot  70 , the strands  64   a  and  66   a  are draped across the bill hook  82 , thereby closing the two lips  83   a  and  83   b  ( FIG. 19 ) of the bill hook  82  because of the pressure of the strands on the upper lip  83   a . Unlike with a typical “Deering” type knotter, the two lips  83   a  and  83   b  are normally opened, unless they are closed by the strands when they are draped across the bill hook  82 . 
   While the strands  64   a  and  66   a  are being delivered across the bill hook  82  to the holder  86 , the finger  118  is actuated to swing inwardly and engage at least the strand  66   a  as illustrated in  FIGS. 9 and 10  for the purpose of seating the same deeply within the crotch  92  so as to assure that the strands  64   a  and  66   a  are both in proper position across the bill hook  82 . 
   When the bill hook  82  rotates around its axis  84 , a cam follower  85 , which is connected to the upper lip  83   a , engages an element having a cam shoulder (not shown). When rotating, the cam follower will push the upper lip  83   a  away from the lower lip  83   b , thus enabling the strands  64   a  and  66   a  to enter in between the two lips  83   a  and  83   b  while the bill hook is rotated. 
   The foregoing described movement on the part of the bill hook  82  and the holder  86  are, of course, brought about by operable inter-engagement of the gear stretch  98  and gear section  106  on the element  76  with their respective gears  96  and  104  on the bill hook  82  and the holder  86 . Such driving inter-engagement continues until a knot has been formed on the bill hook  82  as illustrated in  FIGS. 11 and 12 , by which time the needle  42  has begun to withdraw. At this point, the cam shoulder  114  of the element  76  comes into engagement with the roller  110  of the arm  88  so as to swing the bottom of the latter, and hence the cutter  94 , across that portion of the strands between the bill hook  82  and the holder  86 , thereby severing the same as illustrated in  FIG. 12 . The cutter  94  will move along the retained strands  64   a  and  66   a , and hence cutting these strands loose from the strands  64   b  and  66   b . With reference to  FIG. 12 , it will be seen that at the moment of cutting, the strands  64   a  and  66   a  extend from in between the lips  83   a  and  83   b  towards the holder  86 . On account of the further rotation of the bill hook  82 , the lips  83   a  and  83   b  meanwhile are closed again to clamp the strands  64   a  and  64   b  in between. Considering that the cutter  94  moves very closely alongside the bill hook  82 , the free ends of the cut strands  64   a  and  66   a  extend only over a very short distance out of the lips  83   a  and  83   b . To complete the knot formation, the arm  88  engages the strands  64   a  and  66   a  which are retained in a twisted manner around the bill hook  82 . In so doing, the strand parts lying on top of the lip  83   a  are pulled over the strands parts laying in between the lips  83   a  and  83   b , thereby forming the knot. As described above, since the free ends of the strand  64   a  and  66   a  are very short, they are pulled completely through the knot during its final formation, resulting in the so-called conventional knot  70   a , as best seen in  FIG. 13 . Besides completing the knot, further motion of the arm  88  also strips the finished knot  70   a  completely from the bill hook  82  and drops the completed loop on the bale as illustrated in  FIG. 13 . 
   When the knot  70   a  is dropped by the knotter  40  following severance and stripping from the bill hook  82 , the strand  66   b  from source  74 , as well as strand  64   b  from source  72  is still retained in the second notch of the holder  86 . At this instance, the upper lip  83   a  is open again. Consequently, as the needle  42  continues to retract, the strand  66   b  is draped downwardly across the bale chamber  26  thereby pushing the tooth  83   a  down, while the slack take-up device  154  lowers to its normal position to pull a small amount of additional twine from the source  72 . Upon reaching the condition illustrated in  FIG. 14 , the strands  64   b  and  66   b  are in position for initiating the second tying cycle which is started by the finger  118  (which has been previously returned to its standby position) swinging inwardly to engage the strands  64   b  and  66   b  and seat them deeply within the crotch  92  as shown in  FIG. 15 . This assures that the strands  64   b  and  66   b  are properly positioned across and in engagement with the bill hook  82 , whereupon the latter and the holder  86  are operated by their second respective gear stretch  100  and gear section  108  on the element  76 . Thus, the second knot becomes formed as illustrated in  FIG. 16 , whereupon the arm  88  is once again actuated, but this time by the second cam shoulder  116 . When the tension of leaf-spring  200  is set to a low value, the pressure of the retainer  220  on the holder  86  and hence the force that holds the strands fixed within the holder  86 , will be minimal. 
   Additionally, the supplementary gear section  109  provides a prolonged operation of the holder  86  and will keep the holder  86  rotating over a longer arc. The strands  64   b  and  66   b  are no longer retained between the notch in the holder  86  and the retainer  220 . Therefore, when the arm  88  starts its movement for finalizing the knot formation, the cutter  94  will not be able to effect any cutting action. Indeed, even though the cutter  94  is very sharp, it will act as a blunt knife and will not be able to cut the strands because instead of holding the strands, the holder  86  is releasing them on account of the continued rotation of the holder  86  and the low pressure of the retainer  220  on the holder  86 . The strands will therefore just slide over the knife  94  without being cut, while the arm  88  continues moving and stripping of the almost completed knot from the bill hook  82 , thus pulling the strands out of the holder  86 . This results in the free ends of the strands  64   b  and  66   b  being considerably longer than the free ends obtained during the first knot formation. As such, upon finalizing the knot, free ends  64   b  and  66   b  no longer are pulled completely out of the knot, resulting in a so-called loop-knot  68   b , as best seen in  FIG. 17 . 
   This effect may also be realized without the use of a supplementary gear section  109 . When the tensioning force of the leaf spring  200  to the retainer  220  is sufficiently decreased, then the strands will also be pulled out of the holder  86  by the moving arm  88 , since they are no longer sufficiently held by the holder  86 . 
   This loop-knot  68   b  is the start of a new bight for the next bale. Such bight is in position to receive new material that is packed into the bale chamber  26  by the plunger  30 , and the bight grows in length as additional lengths of the strands  64   b  and  66   b  are simultaneously pulled from their sources  72  and  74 . Finally, when the bale has reached its desired size, the sequence returns to its starting point, whereupon the bight is closed by operation of the needle  42  to complete the loop around the bale and form the other knot. 
   From the foregoing, it will be appreciated that the formation of twine tails  62 ′ and  64 ′, as seen in  FIG. 2 , and as described in U.S. Pat. No. 4,142,746 was inherent only to the formation of a first knot for the next bale (or otherwise said, the second knot obtained during a full cycle of the knotter). In accordance with the present invention, by releasing the strands from the holder  86  before they can become cut during the formation of the second knot in the double-knotter cycle, the generation of twine tails  62 ′ and  64 ′ is avoided. 
   As already explained, two complete tying cycles are carried out during each single revolution of the drive shaft  78 . Thus, each time the needle  42  swings into operation, two different types of knots are formed by the same knotter  40 . The first formed knot is a conventional knot  70  which fully doses the loop of one bale, and the second formed knot is a loop-knot  68  on the next succeeding bale. The cutter  94  only operates to sever the two knots from one another, thereby also disconnecting the two bales from each other.