Abstract:
A variable counterweighted take-up assembly for an endless conveyor system is disclosed, wherein the endless conveyor system has a frame, an endless conveyor belt supported by the frame and is adapted to traverse a predetermined endless path. A take-up section of the conveyor system receives and stores excess portions of the conveyor belt so as to permit operational fluctuations in the length of the belt. The portion of accumulated excess belt is divided into at least two adjacent sections, a first fixed section wherein the length and weight of the belt therein is substantially constant, and a second variable section wherein the length and weight of the belt therein is permitted to vary. The first and second sections are opposed to each other in counterbalance relation in a manner to affect belt tension throughout the conveyor system. The take-up section includes an elongated flexible weighted member having at least two ends, a first end being supported by the accumulated belt portion in the second variable section, and the second end being supported by a fixed frame member spaced from the second variable section. An endless conveyor system which incorporates such variable counterweighted take-up assembly is also disclosed. A method of controlling the excess portions of conveyor belt in the second variable section is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present application relates to variable counterweighted take-up assembly for endless conveyors and endless conveyor system incorporating such take-up assembly. The invention also relates to endless conveyors incorporating such variable counterweighted take-up assembly. Although all types of endless conveyors are included, conveyors having a helical belt path are particularly contemplated. 
     2. Description of the Related Art 
     Endless conveyors of the type contemplated herein generally include an endless conveyor belt which has sufficient flexibility to allow the belt to traverse an endless path from a product input station to a product discharge station, and thereafter to return from one station to the other via a return section. When the conveyor path is straight, the belt must be capable of flexing along an axis generally perpendicular to the path. When the path is other than straight, such as a helical path of the type contemplated herein, the belt must be capable of flexing at least to a limited extent along at least three mutually orthogonal axes in order to permit the belt to traverse such relatively complex paths. 
     In order to permit such multi-directional flexing, such conveyor belts are generally constructed of a plurality of interconnected links which permit at least limited link-to-link articulation along two or more mutually orthogonal axes. In such instances, the links are generally constructed of a material such as steel making the weight of the belt a relatively significant factor in operating the conveyor system. 
     Conveyor belts of the type contemplated herein generally range from about 12 inches to about 60 inches in width and from about 200 feet to about 2,500 feet in length, and even up to about 3,000 feet in some instances. When a conveyor belt is constructed of numerous interlocked steel links and is between 10 and 60 inches in width and more than 200 feet in length, the weight of the belt becomes a significant factor to reconcile. For example, the belt must be driven through the work path which begins at the product input station and ends at the product discharge station. Thereafter, the belt enters the return section where it reverses direction and re-enters the product input station to continue operating in its endless path. In helical conveyors, the belt is driven up a helical shaped path in an up-go conveyor, and down a helical shaped path in a down-go conveyor. The belt is generally driven by friction forces imparted to it along the inner edge by a circular shaped rotating cage around which the belt is wrapped in the work zone, and it is provided with additional assistance by a motor driven sprocket which is constructed to engage the links of the belt directly as it is rotatably driven by the assist motor. Such motor assist is particularly needed in up-go helical conveyors where the relatively heavily weighted belt is made to traverse an up-go helical path against the force of gravity. A motor driven assist sprocket is also utilized in helical shaped down-go conveyors, although the gearing and roller arrangements differ somewhat from the up-go conveyors, and the assist force required is somewhat different. In other applications, the work zone of the conveyor path is straight. 
     Conveyor belts of the type contemplated herein are generally used for conveying products under various conditions. For example, in some applications, the belts are used to convey dough products through relatively high temperature atmospheres in order to assist the dough in rising prior to formation of a bread product. In other applications, the belts may be made to carry food products through relatively cold atmospheres, sometimes under freezing conditions. In still other applications, the belts may be required to conduct products at room temperature. 
     In each instance, the belt, being made of a plurality of interlocked metal links, will react to the surrounding conditions such as temperature, cleanliness and the like, with the result that the belt will undergo a natural stretch or compression such factors will, in turn, affect the belt tension. In some instances, the belt will become longer during operation and, in others, the belt may become shorter, and such variations in these vital parameters have necessitated the incorporation of a take-up section in the belt return section of the system in order to permit the accumulation of excess belt and to accommodate the increases and decreases in the length of the belt. Further, since the belt is constructed of numerous interconnected links, variations in the link-to-link spacing at any given time will also accumulate to change the overall length of the belt. 
     In helical conveyors, the belt will undergo compression along the inner edge of an arcuate turn and stretch along the outer edge, thus resulting in relatively complex changes in the overall conditions such as tension and length of the belt. These changes have also been found to affect the overall tension in the belt throughout the system, with the result that in some instances, particularly where sanitary conditions are not observed, the belt tension will differ between separate locations along the path. 
     It has been found that ideally, belt tension should be maintained as uniform as possible, and this objective has often been met with some success in the past by incorporating a take-up section in which excess belt is permitted to accumulate. In the take-up section, the excess belt is made to pass through two adjacent sections, a first fixed section and a second variable section. In the first fixed section, a portion of belt is maintained in the form of a vertical curtain of fixed length and weight. In the second variable section, the excess belt is looped under and about a floating dancer roller so as to assume a generally V-shaped configuration, and is permitted to increase and decrease in dependence upon increases or decreases in the length of the belt as may be caused by operating conditions. The weight of the portion of belt in the second variable section belt is maintained in counterbalance relation to the weight of the curtain of belt in the first fixed section such that when the length and weight of the belt in the second fixed section increases, the dancer arm moves to its lowermost position, and when the length and weight of the belt in the second variable section decrease, the dancer arm moves upwardly toward its uppermost portion. 
     In order to maintain a proper balance between the portions of belt in the first fixed and second variable sections, prior art systems have attached a fixed weight to the dancer arm in the second variable section. The weight is intended to complement the weight of the belt portion therein and to counterbalance the weight of the vertical curtain of belt in the first fixed section. It can be readily appreciated that a balanced or unbalanced condition between the two sections will in turn affect the tension on the belt in the entire endless system. Accordingly, the need to maintain a proper balance between the first and second systems is readily obvious. Ideally, it is preferable to maintain the weight of the belt portion in the second variable section at a constant level, or at least to within a predetermined relatively narrow range substantially equal to the weight of the belt portion in the first fixed section. 
     U.S. Pat. No. 4,189,047 to Beckius relates to an endless conveyor wherein the tension of the belt carrying the product cannot be readily adjusted during operation. A progressive counterweight is provided for tensioning the belt where lengthening of the portion of the belt carrying the product automatically reduces the tension force and shortening the belt carrying the product automatically increases the tension force. The amount of weight varies depending upon the vertical positioning of weights and supports within a column  70 . German Patent No. 263,275 relates to a conveyor belt tensioner which acts during extreme conditions. Tensioning drum  1  is connected by a tensioning cable  2  to a one-side supported load lever  5 , which carries ballast  6 . A force created by weights  6  varies depending upon the angle of supported load lever  5 . 
     In present conveyor systems of the type contemplated herein, with belts of relatively small sizes, it has been possible to maintain a reasonable condition of balance between the first and second sections of the take-up section utilizing a fixed weight attached to the dancer roller arm. However, with conveyor belts increasing in width and length, a condition of balance has been more and more difficult to achieve, with the result that belt tension has also become erratic and difficult to control. With additional factors such as sanitary conditions and temperature changes also affecting the systems, prior art endless conveyor systems have been adversely affected in these respects. I have invented a variable counterweighted take-up assembly for an endless conveyor system, and an endless conveyor system having such variable counterweighted take-up assembly which avoids the disadvantages of presently known systems by providing precise control of the amount of supplemental weight added in the variable section of the take-up section of the conveyor system in accordance with specific needs at any time. I have also invented a method of controlling the weight of the belt portion in the second variable section in counterbalance to the first fixed section. 
     SUMMARY OF THE INVENTION 
     A variable counterweighted take-up assembly for an endless conveyor system is disclosed, the endless conveyor system having a frame, an endless conveyor belt supported by the frame and adapted to traverse a predetermined endless path, and a take-up section wherein excess portions of the conveyor belt are allowed to accumulate so as to permit operational fluctuations in the length of the belt. The portion of accumulated excess belt in the take-up section is divided into at least two adjacent sections, a first fixed section wherein the length and weight of the belt therein is substantially constant, and a second variable section wherein the length and weight of the belt therein is permitted to vary. The first and second sections are opposed to each other in counterbalance relation in a manner to affect belt tension throughout the conveyor system. According to the invention, the take-up section comprises an elongated flexible weighted member having at least two ends, a first end supported by the accumulated belt portion in the second variable section, and the second end supported by a fixed frame member spaced from the second variable section. 
     Preferably, the elongated weighted member comprises a plurality of individual weight members connected to each other in a manner to permit pivotal articulated movement relative to each other between the second variable section and the fixed frame member so as to permit flexible movement of the weighted member between the second variable section and the fixed frame member in dependence upon variations in the accumulated portion of excess belt in the second variable section. The individual weight members are preferably generally rectangular in shape, and are preferably connected to each other by at least one link chain to permit the pivotal articulated movement relative to each other. Preferably, two link chains are provided, one chain adjacent each of the shorter sides of the rectangular weight members. 
     The first fixed section and second variable section are preferably positioned within a return section of the conveyor belt wherein the conveyor belt returns from a product discharge station to a product input station while reversing belt direction. The portion of conveyor belt in the first fixed section is in the form of a vertical curtain of belt having an upper and a lower end, and a roller member is positioned at each end for directing the belt along its path within the section. The second variable section is comprised of excess conveyor belt which is directed beneath and around at least a portion of a floating dancer roller so as to assume a generally V-shaped elevational configuration in elevation, whereby the weight of the generally V-shaped excess conveyor belt in the second variable section is opposed in counterbalance relation to the weight of the conveyor belt in the first fixed section, and the elongated flexible weighted member is appended to the floating dancer arm to complement the weight of the excess conveyor belt in the second variable section. The floating dancer arm is permitted to move upwardly and downwardly in dependence upon the amount of excess belt in the second variable section, and the weight of the elongated flexible weighted member is permitted to transfer between the floating dancer arm and the fixed frame member in dependence upon the vertical position of the floating dancer arm as determined by the amount of excess belt in the second variable section. 
     A substantial portion of the weight of the elongated flexible weighted member is transferred to the floating dancer arm when the excess belt in the second variable section is at a minimum and the floating dancer arm is located at its uppermost vertical portion, and a substantial portion of the weight of the flexible weighted member is transferred to the fixed frame member when the weight of the excess belt in the second variable section is at a maximum and the floating dancer arm is located at its lowermost vertical position. The second variable section communicates with the discharge station of the conveyor belt by a plurality of roller members. 
     The flexible weighted member is preferably comprised of a plurality of rectangular shaped steel plates and the link chains are preferably bicycle-type link chains having at least one selected link respectively attached to each rectangular shaped steel plate to permit the pivotal articulated movement. The elongated flexible weighted member may also be an elongated unitary flexible member having weight members secured thereto to provide supplementary weight to the flexible member. Alternatively, a unitary flexible member made of a heavy metal such as lead may be provided, weight permitting. 
     The invention also relates to an endless conveyor system having a variable counterweighted take-up assembly, which comprises a frame, a flexible endless conveyor belt supported by the frame and adapted to traverse a predetermined endless path, a conveyor belt take-up section which permits excess portions of the conveyor belt to accumulate so as to permit operational fluctuations in the length of the belt. The accumulated belt portion is divided into at least two spaced sections, a first fixed section wherein the length and weight of the belt is substantially constant, and a second variable section wherein the length and weight of the belt therein is permitted to vary. The first and second sections are opposed to each other in counterbalance relation in a manner to affect belt tension in the endless conveyor belt. An elongated flexible weighted member has at least two ends, a first end appended to the second variable section, and a second end connected to a fixed frame member spaced from the second variable section. 
     The conveyor belt traverses a path having an input station and a discharge station communicating with each other by a return section, and the conveyor belt is directed from the discharge station around a plurality of roller members so as to reenter the input station in direction opposite the direction of the discharge station. The take-up section is located in the return section of the conveyor system. The elongated flexible weighted member preferably comprises a plurality of individual weight members connected to each other in a manner to permit pivotal articulated movement relative to each other between the second variable section and the fixed frame member so as to permit flexible movement of the weighted member between the second variable section and the fixed frame member in dependence upon variations in the accumulated portion of excess belt in the second variable section of the take-up section. 
     The second variable section is comprised of excess conveyor belt which is directed beneath and around at least a portion of a floating dancer roller so as to assume a generally V-shaped elevational configuration, such that the weight of the generally V-shaped excess conveyor belt in the second variable section is opposed in counterbalance relation to the weight of the conveyor belt in the first fixed section. The elongated flexible weighted member is preferably appended to the floating dancer arm to complement the weight of the excess conveyor belt in the second variable section. The floating dancer arm is permitted to move upwardly and downwardly in dependence upon the amount of excess belt in the second variable section, and the weight of the elongated flexible weighted member is permitted to transfer between the floating dancer arm and the fixed frame member in dependence upon the vertical position of the floating dancer arm as determined by the amount of excess belt in the second variable section. It can be seen that a substantial portion of the weight of the elongated flexible weighted member is transferred to the floating dancer arm when the excess belt in the second variable section is at a minimum and the floating dancer arm is located at its uppermost vertical position, and a substantial portion of the weight of the flexible weighted member is transferred to the fixed frame member when the weight of the excess belt in the second variable section is at a maximum and the floating dancer arm is located at its lowermost vertical position. The second variable section communicates with the discharge station of the conveyor belt by a plurality of roller members. The elongated flexible weighted member is preferably comprised of a plurality of rectangular shaped steel plates flexibly connected by one or more link chains of a bicycle-type having at least one selected link respectively attached to each rectangular shaped steel plate to permit the pivotal articulated movement. 
     The flexible conveyor belt preferably traverses a helical path having a product input station and a product discharge station and the return section communicates the product discharge station and the product input station with each other. The conveyor belt may be adapted to travel in an upward direction along the helical path from the product input station to the product discharge station, or alternatively, the conveyor belt may be adapted to travel in a downward direction along the helical path from the product input station to the product discharge station. Still alternatively, the conveyor belt may be adapted to travel along a straight path between the product input station and the product discharge station and the return section communicates the product discharge station with the product input station. Also, the conveyor belt may be adapted to travel in either of two directions along the straight path. 
     In the preferred embodiment, an endless conveyor system is disclosed having a variable counterweighted take-up assembly, which comprises a frame, a flexible endless conveyor belt supported by the frame and adapted to traverse a predetermined endless path about a rotating cage, at least a portion of the endless path being helical. A conveyor belt take-up section permits excess portions of the conveyor belt to accumulate so as to permit operational fluctuations in the length of the belt, the accumulated belt portion being divided into at least two spaced sections, a first fixed section wherein the length and weight of the belt is substantially constant, and a second variable section wherein the portion of belt therein extends under and at least partially about a floating dancer roller so as to assume a generally V-shaped configuration. The length and weight of the belt in the second variable section is permitted to vary while permitting the dancer roller to move between the lowermost and uppermost vertical positions in dependence upon the amount of excess belt in the second variable section. The first and second sections are opposed to each other in counterbalance relation in a manner to affect belt tension in the endless conveyor belt. An elongated flexible weighted member has at least two ends, a first end appended to the second variable section, the second end connected to a fixed frame member spaced from the second variable section. 
     A method is disclosed for controlling excess portions of conveyor belt in an endless conveyor system having a frame, an endless conveyor belt adapted to traverse a helical path about a rotating cage which provides belt driving force by frictional engagement with an inner edge of the belt, a take-up section for receiving excess portions of belt caused by operational fluctuations in the length of the belt, the take-up section being divided into at least two sections, a first fixed section wherein the length and weight of the belt portion therein is substantially fixed, and a second variable section wherein the length and weight of the belt therein is permitted to vary, the first and second sections being opposed to each other in counterbalance relation in a manner to affect belt tension throughout the conveyor system. The method comprises selectively complementing with additional weight, the weight of the portion of belt in the second variable section in a manner to maintain the combined weight therein substantially constant, or at least to within a predetermined range. 
     The step of complementing the weight of the portion of belt in the second variable section is accomplished by supporting one end of an elongated flexible weighted member by the portion of belt in the second variable section and supporting the other end of the elongated flexible weighted member by a fixed member spaced by a predetermined distance from the second variable section, such that when the weight of the belt portion in the second variable section increases, the amount of complementary weight supported thereby decreases, and when the weight of the belt portion in the second variable section decreases, the amount of complementary weight supported thereby increases. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described hereinbelow with reference to the drawings, wherein: 
     FIG. 1 is a front, right-side perspective view from above, of an up-go helical conveyor, incorporating a fixed weight counterbalance system constructed according to the prior art; 
     FIG. 2 is a front, right-side perspective view from above, similar to FIG. 1, of a helical conveyor, incorporating a variable weight counterbalance system constructed according to the present invention; 
     FIG. 3 is a right-side perspective view of the variable weight counterbalance system of the conveyor shown in FIG. 2, greatly enlarged for illustration purposes and shown in relation to the conveyor frame; 
     FIG. 4 is a right-side perspective view, greatly enlarged, of the variable weight counterbalance system shown in FIG. 3; 
     FIG. 5 is a right-side perspective view, greatly enlarged, of a variable weight counterbalance system for a conveyor similar to the system shown in FIG. 4, incorporating an alternative type of connecting device for the individual plate-like weight members of the variable weight counterbalance system; 
     FIG. 6 is a front elevational view of the fixed weight counterbalance system shown in the take-up section of the up-go conveyor of FIG. 1, illustrating the condition of the conveyor belt having an average amount of excessive belt in the take-up section; 
     FIG. 7 is a front elevational view of the fixed weight counterbalance system of the take-up section of a down-go conveyor similar to the up-go conveyor of FIG. 6, illustrating the condition of the conveyor belt having an average amount of excess belt in the take-up section; 
     FIG. 8 is a front elevational view of the variable weight counterbalance system of the take-up section of an up-go conveyor shown in FIG. 2, illustrating the condition of the conveyor belt having substantially a minimum amount of excess belt in the take-up section; 
     FIG. 9 is a front elevational view of the conveyor belt and variable weight counterbalance system of the take-up section of an up-go conveyor as shown in FIG. 8, illustrating the condition of the conveyor belt having an average amount of excess belt in the take-up section; 
     FIG. 10 is a front elevational view of the conveyor belt and variable weight counterbalance system of the take-up section of an up-go conveyor as shown in FIG. 9, illustrating the condition of the conveyor belt having substantially a maximum amount of excess belt in the take-up section; 
     FIG. 11 is a front elevational view of the variable weight counterbalance system of the take-up section of a down-go conveyor, illustrating the condition of the conveyor belt having substantially a maximum amount of excess belt in the take-up section; 
     FIG. 12 is a front elevational view of the conveyor belt and variable weight counterbalance system of the take-up section of a down-go conveyor as shown in FIG. 11, illustrating the condition of the conveyor belt having an average amount of excess belt in the take-up section; 
     FIG. 13 is a front elevational view of the conveyor belt and variable weight counterbalance system of the take-up section of a down-go conveyor as shown in FIG. 12, illustrating the condition of the conveyor belt having substantially a minimum amount of excess belt in the take-up section; 
     FIG. 14 is a partial cross-sectional view, greatly enlarged, of the floating variable weight counterbalance system shown in the conveyor of FIGS. 2 and 4, illustrating a preferred method of construction of the variable counterbalance weight utilizing a bicycle-type link chain; and 
     FIG. 15 is a front elevational view of a straight conveyor incorporating the variable weight counterbalance system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, there is illustrated a front, right side perspective view from above, of an up-go helical conveyor  10 , incorporating a fixed weight counterbalance system constructed according to the prior art. The conveyor  10  is supported on frame  11  and includes flexible conveyor belt  12  having take-up section  14  in which excess belt  22  is collected in order to maintain continuity of belt movement as well as a predetermined belt tension throughout the conveyor system. The amount of excess belt  22  either lengthens or shortens in dependence upon operative conditions in the entire conveyor system as will be described in greater detail hereinbelow. 
     Referring again to FIG. 1, the conveyor belt  12  is flexible and is particularly constructed of interconnected links which make it capable of flexing along at least two, but preferably three mutually orthogonal directions so as to be directed along a continuously changing arcuate path to assume a helical shape as shown in FIG.  1 . 
     The helical path begins after the “infeed” section  16  wherein products (i.e. food products such as bread, etc.) are introduced, and is followed by a discharge section  18  in which the products are discharged. One example of an endless conveyor belt construction of the type contemplated herein is described in U.S. Pat. No. 3,664,487 to Ballenger, the disclosure of which is incorporated by reference herein and made a part of this disclosure. Another example of such belt construction is disclosed in U.S. Pat. No. 4,846,339 to Roinestad, the disclosure of which is incorporated herein by reference and made a part of this disclosure. All types of belts of flexible construction as disclosed herein are contemplated. 
     Referring again to FIG. 1, the flexible conveyor belt  12  traverses a helical path as shown, beginning after the product infeed station  16  and terminating just prior to the product discharge station  18 . Between product infeed and discharge stations  16  and  18 , he belt wraps around a rotating cage  20  driven by main drive  21 , which is in ontinuous frictional engagement with the inner edge of the belt in the helical portion. The frictional engagement drives the belt through its endless path, and it returns to the infeed station via return section  23  after passing through the take-up section  14 . 
     The belt is generally of relatively substantial weight due to the intricate metal link construction. Accordingly, a sprocket  15  driven by motor  17  is incorporated into the take-up section to provide assistance to the belt to move along its helical path. The sprocket  15  and drive motor  17  are shown schematically in FIG. 1, FIGS. 6 and 7. It can be seen that by directing the flexible conveyor belt through the helically shaped path, products are made to travel through significantly large distances, in a relatively limited space. 
     As noted, as the belt leaves the rotating cage and enters the take-up section  14 , a sprocket  15  driven by motor  17  applies a driving force to the belt to assist its movement along the helical path and to provide assistance in maintaining the belt under tension within a predetermined range. By maintaining the tensile force on the belt to within a predetermined range, the friction force between the rotating cage  20  and the belt  12  is also regulated. Regulation of belt tension is particularly significant, since excess belt tension will cause the cage-to-belt friction force to be higher and excessively low belt tension will cause the cage-to-belt friction force to be reduced excessively so as to adversely affect the belt drive force. 
     In practice, the rotational speed of the outer surface of the rotating cage is controlled to exceed the corresponding rotational speed of the inner edge  11  of the belt  12  such that a relatively precisely controlled slippage occurs between the cage  20  and the belt  12 , thereby acting in concert with the drive motor  17  and driven sprocket  15  to maintain the belt tension to within the predetermined range. However, it has been determined that factors such as temperature, cleanliness, natural belt stretch or the like often affect the belt and cause it to either become longer or shorter due particularly to the fact that it is constructed of numerous interconnected metallic links. Thus, cumulative effects of link spacing and the like serve to cause this lengthening or shortening of the belt. In such case, the operative parameters of the belt, such as tension, cage friction, etc., are also affected, thereby potentially impairing the conveyor operation. For example, when the belt undergoes excessive stretch, there is an excessive amount of accumulated excess belt  22  in the variable section of take-up section  14 , with the result that the excessive weight of the belt in the take-up section applies excessive force to the remainder of the belt through the belt return section  23 . Similarly, when the belt undergoes excessive shortening by temperature conditions, sanitary considerations or the like, the weight of the excess belt  22  in the variable section of take-up section  14  is reduced and must be complemented by an additional weight. However, if the belt becomes shorter to an extent where it is subjected to excessive tension forces, such tension is applied to the entire belt via the belt return section  23 . 
     In present day conveyors, as shown in FIG. 1, a fixed weight  24  is appended from the excess belt  22  in the take-up section  14  in order to control the weight of the portion  22  of the conveyor belt in the variable section of take-up section  14  which does not carry products. In particular, the portion of excess belt  22  in the variable section of take-up section  14  passes under a floating dancer arm  26  to form a V-shaped configuration, and thereafter it extends around roller  28  to form a vertical curtain  30  of conveyor belt. The vertical curtain  30  and the V-shaped section  22  are best characterized respectively as fixed and variable sections of the take-up section and are operative to counteract each other such that the weight of the V-shaped section  22 , which varies in dependence upon the amount of excess belt in the system, counteracts the weight of the vertical curtain  30 . Accordingly, as the variable V-shaped section  22  increases in length due to an increase in the overall belt length, it increases correspondingly in weight, and thereby applies greater tensile force to the opposing vertical curtain  30 . Similarly, when the excess amount of belt reduces in length, the vertical length of the V-shaped section  22  also becomes shorter and reduces in weight so as to apply less counterbalance force to the vertical curtain  30 . 
     As noted hereinabove, in order to provide assistance in controlling the tension on the vertical curtain  30  in existing conveyors, as well as on the entire belt in the endless conveyor, a fixed weight  24  is appended to the V-shaped section  22 , as shown in FIG.  1 . The combined weight of the V-shaped section  22  and the fixed weight  24  act in concert to counterbalance the weight of the vertical curtain  30 . 
     While the use of a fixed weight  24  has been somewhat successful in the past to maintain the tension on the conveyor belt to within a predetermined range, as conveyors have become larger in both length and width, conveyor belts have become correspondingly larger and the belts have become significantly greater in weight. Accordingly, the weight of the excess belt  22  in the take-up section has increased, and it has become increasingly difficult to maintain the correct amount of tension on the conveyor belt using the fixed weight  24  in the take-up section as shown in FIG.  1 . Accordingly, the present invention as shown in FIG. 2 has been developed to overcome these disadvantages and to provide a precisely regulated system of weight control in the take-up section. 
     Referring now to FIG. 2, there is illustrated an up-go conveyor  32  which incorporates a variable weight counterbalance system in the take-up section in accordance with the present invention. With the exception of the variable weight counterbalance system which will be described hereinbelow, the conveyor  32  is supported on frame  33  and is the same as the conveyor  10  disclosed in FIG.  1 . In FIG. 2, conveyor  32  is supported on frame  33  and includes conveyor belt  34  which traverses a helical path as shown, beginning at a point following the product infeed station  36  and terminating just prior to the product discharge station  38 . Between product infeed station  36  and product discharge station  38 , the belt wraps around rotating cage  40  driven by main drive  41 , and is caused to traverse a helical path by frictional engagement between the cage  40  and the belt  34  in a manner similar to that disclosed in connection with the conveyor shown in FIG.  1 . Motor  37  drives sprocket  35  which engages the belt as shown to assist the movement of the belt along the endless path. 
     As shown in the conveyor  10  of FIG. 1, conveyor  32  in FIG. 2 includes a take-up section  42  in which excess belt accumulates in the form of V-shaped section  44  of the variable section, which provides counterbalance to vertical curtain  46  of the fixed section of take-up section  42 , with floating dancer arm  48  and roller  50  operative in the same manner as described for floating dancer arm  26  and roller  28  in FIG. 1, respectively. 
     Referring again to FIG. 2, the V-shaped section  44  of belt  34  in the take-up section is attached to a dancer arm  48  located at the lowermost end of the V-shaped section  44 . The variable weight  52  is comprised of a plurality of individual generally rectangular-shaped weights  54 , connected by bicycle-type link chain  56 , shown more clearly in FIGS. 3 and 4. Link chains  56  are attached to plates  54  as shown, by bolts or screws  58  to permit the individual plates  54  to articulate with respect to each other as permitted by individual pivotal motion of links of chain  56 . One link chain  56  equidistant from the opposite end of plates  54  is not shown, but is behind the portion of belt  44 . 
     Referring now to FIG. 4, there is illustrated a perspective view of the variable weight counterbalance system  52  shown in FIG. 3, but in greater and enlarged detail. The individual plates  54  of the variable weight  52  are shown in greater detail in FIG. 4, and the individual links  60  of bicycle-type link chain  56  are also shown in greater detail. As can be seen, the links  60  are selectively and individually attached to the plates by bolts or screws  62 . Floating dancer arm  48  is mounted for rotation via bearings  64  which are separated by rigid rods  68  connected to support plate  70 . Alternative devices to flexibly connect weights  52  may be utilized as illustrated generally in FIG. 5, wherein weights  54  are connected to each other by a flexible strap or other similar device  57 . Additionally, a flexible unitary weighted strap may be utilized, where possible, to control the weights required. 
     Referring again to FIGS. 3 and 4, support plate  70  has connected thereto the variable counterbalance weight  52  via link chain  56 . The lower end of the variable  25  counterbalance weight  52  is connected by link chain  56  to support plate  70  as shown, whereas the upper end of variable counterbalance weight  52  is connected to a fixed support  74  connected to frame  33 , as shown in FIG.  4  and as best seen in FIGS. 8,  9  and  10 . 
     The operation of counterbalance weight  52  is best described in connection with FIGS. 8,  9  and  10  which illustrate the counterbalance system of the take-up section  42  of an up-go conveyor as shown in FIGS. 2,  3  and  4 . Referring to these Figs., FIG. 8 illustrates fixed section  46  and variable section  44  of the take-up section  42  of up-go conveyor  32  shown in FIG. 2, showing the counterbalance weight  52  of the variable section constructed according to the present invention. FIG. 8 illustrates the condition wherein the conveyor belt has substantially a minimum amount of excess belt in the take-up section. FIG. 9 illustrates take-up section  42  of the up-go conveyor  32  as shown wherein the conveyor belt has an average amount of excess belt in the take-up section. Finally, FIG. 10 illustrates the take-up section  42  of the up-go conveyor  32  wherein the conveyor belt has substantially the maximum amount of excess belt in the take-up section. 
     As can be seen from FIG. 8, when a minimum amount of excess belt  44  is accumulated in the take-up section, the vertical dimension of excess belt  44  is lessened causing dancer arm  48  to be raised to the highest vertical level shown. Counterbalance weight  52  actually shifts toward the floating dancer arm  48  and increases the portion of weight  52  carried by the dancer arm  48 , while simultaneously reducing the portion of weight  52  carried by the fixed support  74 . Accordingly, it can be seen that the arrangement of the variable counterbalance weight  52  actually complements the movements of the excess belt  44  in the take-up section  42  by increasing the portion of weight  52  carried by dancer arm  48  and excess belt  44  when excess belt  44  is lesser in weight as shown in FIG.  8 . 
     Referring now to FIG. 9, there is illustrated the take-up section of the conveyor wherein the excess belt in the take-up section is of average length. By average length is meant that it is approximately intermediate the minimum length of excess belt  44  shown in FIG.  8  and the maximum length of excess belt  44  shown in FIG.  10 . It is apparent from FIG. 9 that the variable weight  52  is divided substantially equally between fixed frame member  74  and floating dancer arm  48 , except that in FIG. 9 the excess belt forms a V-shaped configuration prior to passing over roller  50  to form vertical curtain  46 , which counterbalances the weight of excess belt  44 . 
     Referring now to FIG. 10, there is illustrated the take-up section of the up-go conveyor wherein the excess conveyor belt  44  in the take-up section is substantially a maximum length. In this instance, since the length of the excess conveyor belt  44  is greater, the weight of the excess belt  44  forming the V-shaped section in the take-up section will be corresponding greater, causing the dancer arm  48  to be lowered to its lowermost position as shown, and thereby causing the individual weights  54  of variable counterbalance weight  52  to shift towards the fixed support  74  such that most of the weight is carried by the fixed support  74  and a substantially minor amount of the weight  52  is carried by the V-shaped section of excess belt  44  in the take-up section. 
     In summary, the operation of the variable counterbalance weight shown in FIGS. 8,  9  and  10  will be readily apparent to persons skilled in the art. When the weight of the excess belt  44  shown in FIG. 8 is at a minimum, a maximum portion of the variable counterbalance weight is operative to assist in maintaining a predetermined tension on the conveyor belt throughout the entire conveyor system. When the weight of the excess conveyor belt  44  in the take-up section  42  is at a maximum as shown in FIG. 10, a minimum portion of the variable counterbalance weight  52  is added to the weight of the excess belt  44 , thereby permitting substantially the entire weight of the excess belt in the take-up section to counterbalance the first fixed section and thereby control the tension on the conveyor belt in the entire system. Lastly, as seen in FIG. 9, when the length of the excess conveyor belt  44  in the take-up section  42  is an average amount, the portion of the variable counterbalance weight  52  is at a proportionately corresponding medial amount and therefore will complement the weight of the excess belt in the take-up section up to a predetermined medial amount. It is preferable to maintain the weight of the portion of belt in the second variable section constant, or at least within a predetermined narrow range, approximately equal to the weight of the curtain of belt in the first section. 
     It can be appreciated that the individual material and dimensions of the individual weights  54  which form the counterbalance weight  52  can be precisely calculated and defined to provide a relatively constant downward force in the take-up section by determining the weight of each individual segment  54  so as to properly complement the weight of the excess belt  44  in the take-up section. By providing the appropriate predetermined dimensions and weight of each segment, and by determining the optimum distance “A” between dancer arm  48  and fixed frame member  74 , as shown for example in FIGS. 9 and 11, the variable counterbalance weight can be constructed to provide a substantially constant downward force on the entire conveyor belt system through the take-up section. This constant downward force is predetermined and substantially accurate and contrasts significantly with the relatively unpredictable downward force which is provided on the conveyor belt in the up-go conveyor shown in FIGS. 1,  6  and  7  wherein only one fixed weight  24  was incorporated to complement the weight of the V-shaped section of excess belt in the take-up section. Further, it can be envisioned that the variable counterweight  52  can be made longer or shorter, depending upon individual needs in each conveyor, and upon the actual predetermined tension force required. 
     Finally, it is envisioned that the weight  52  can also be constructed as a continuous flexible weighted material which would provide even more precision in complementing the weight of the excess belt in the take-up section. For example, a flexible material such as plastic or rubber can be provided with a dense heavy material, such as lead pellets embedded therein to provide a precise and continuous shifting of weight between the fixed support and the excess belt in the take-up system. As noted above, alternatively the flexible material can be a continuous heavy metal such as lead where permitted by the weight requirements. 
     Referring now to FIG. 7, there is illustrated the take-up section of a down-go conveyor constructed according to the prior art wherein a fixed weight  24  is incorporated to complement the weight of the generally V-shaped excess belt in the take-up section. As can be seen from FIG. 7, the down-go conveyor is similar to the up-go conveyor shown in FIG. 2, with the exception that in the helical portion of the belt path, the belt travels in the downward direction and the roller arrangement for reversing the direction of the conveyor belt is distinct from the roller arrangement in FIGS. 2 and 6. 
     Referring now to FIGS. 11,  12  and  13 , there is illustrated the take-up section of a down-go conveyor which incorporates the variable counterbalance weight system constructed according to the present invention. The operation of the down-go conveyor is similar to the up-go conveyor described in connection with FIGS. 2-4 and  8 - 10 . However, in the down-go conveyor, the conveyor belt traverses a helical path in the downward direction, opposite the direction shown in FIG.  2 . Accordingly, the location of the product infeed station in the up-go conveyor becomes the product discharge station in the down-go conveyor and the location of the product discharge station in the up-go conveyor becomes the product infeed station in the down-go conveyor. 
     The down-go conveyor is driven by the rotating cage as disclosed in the up-go conveyor. Also, a sprocket  35  is positioned in engagement with the links of the belt and is driven by motor  37  to assist the movement of the belt along its path. A typical arrangement of the motor  37  and direction reversing rollers for a down-go conveyor is shown in FIGS. 11-13. 
     Referring now to FIG. 14, the variable counterbalance weight  52  shown in FIGS. 2,  3  and  4  is shown in cross-section and in greater enlarged detailed. As can be seen, the individual rectangular plates  54  are respectively connected to individual links  60  of link chain  56  by bolts or screws  62 . FIG. 14 also illustrates in greater detail the continuous structure of the variable counterbalance weight  52  in that the individual plates are capable of gradually shifting from the fixed frame member  74  to the floating dancer arm  48  to provide a continuous transfer of the weight between the fixed support  74  and the floating dancer arm  48  as needed by the weight of the generally V-shaped portion of excess belt  44  in the take-up section. It can be fully appreciated, particularly by FIG. 14, that the dimensions of the plates  54  and the spacing of the plates with respect to each other can be calculated and determined to provide whatever degree of precision may be required in individual circumstances to shift the weight in an appropriate manner between the dancer arm  48  and the fixed support  74 . In addition, the material utilized to construct the plates, and the density of that material can also be calculated and determined to provide precision in complementing the weight of the excess belt in the take-up section. A typical preferred embodiment includes rectangular plates  54  fabricated of stainless steel. 
     Moreover, as noted, it can be appreciated that although a bicycle-type link chain  56  has been illustrated to connect the individual plates, any suitable connecting device which will permit the plates to articulate in pivotal fashion with respect to each other in a manner similar to that shown in the drawings is contemplated. Finally, depending upon the weight requirements in each instance, it is envisioned that the variable weight  52  can be substituted by a flexible continuous belt made of a dense heavy material, whereby the individual weights can be eliminated. For example, a flexible plastic belt having dense material such as lead pellets embedded therein may be provided. 
     Referring now to FIG. 15, there is shown a straight conveyor  100  which includes conveyor belt  102  having a return section  104  and a variable counterbalance weight  106  connected to a generally V-shaped excess belt section  108  in the take-up section via floating dancer arm  110 . The variable counterbalance weight  106  is connected at one end to the floating dancer arm  110  in the same manner as described in the previous embodiment, and at the other end to a fixed support  112  connected to frame  114  as described in the previous embodiment. Although the conveyor belt  102  shown in FIG. 15 is an endless straight conveyor belt as compared to the helical endless conveyor belt shown in the previous Figs., the operation of the belt with respect to the excess amount of belt accumulated in the tale-up section is identical to the disclosures of the previous embodiment.