Abstract:
Wing pulleys that engage a conveyor belt during conveying operations are described. The wing pulley includes a central reinforcing disk that strengthens and stabilizes the pulley.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. patent application Ser. No. 12/823,528, filed Jun. 25, 2010 and is a continuation of U.S. patent Ser. No. 13/010,286, filed Jan. 20, 2011, each of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The field of the present disclosure relates to belt conveyor pulleys and, particularly, to wing pulleys that engage a conveyor belt during conveying operations. In various embodiments, the wing pulley includes a central reinforcing disk that strengthens and stabilizes the pulley. 
     During mining and other bulk transport operations material must be transported over long distances in order to load the material by truck or rail. Further, such material must be unloaded and transported for processing. Among the common means for transport are bulk conveyors which are capable of transporting large amounts of material quickly and reliably and without significant cost. Typical conveyors that may be employed include drag, screw, belt and pneumatic conveyors. 
     Belt conveyors are well suited for use in many transport applications and are particularly well suited for use in mining operations. Belt conveying systems include at least two pulleys and a conveyor belt which rotates about the two pulleys. Material is loaded onto the belt at a tail section and is unloaded via gravity at a head section. A tail pulley and head pulley allow the belt to travel from the point at which material is loaded to the point it is unloaded and back again. The conveying system may also include take-up pulleys to provide proper belt tensioning, bend pulleys to change the direction of travel of the belt and snub pulleys, typically located adjacent the drive pulley, to increase the contact with the drive pulley and/or provide belt tensioning. The belt may be driven at a number of positions including the tail section or head section of the conveyor system. 
     At the tail section of the conveying system (the section at which material is loaded onto the conveyor belt), some amount of bulk material may undesirably fall on the lower portion of the belt traveling toward the tail pulley rather than on the upper portion of the belt traveling away from the tail pulley. This material comes into contact with the tail pulley and causes wear of the tail pulley components, and may even lead to pulley failure, resulting in costly downtime and/or replacements. Unless this material is properly discharged, it may be rebroadcast onto the belt causing further wear of the pulley. 
     A continuing need exists for conveyor pulleys that are capable of discharging unwanted material from the conveyor system without sacrificing pulley strength and reliability relative to conventional pulley designs. A further need also exists for reliable conveying systems and methods for conveying bulk materials that use such conveyor pulleys. 
     SUMMARY 
     In one aspect of the present disclosure, a conveyor pulley includes a shaft, a reinforcing disk and a first and second plurality of wings. The shaft includes a central portion, a first coupling portion and a second coupling portion. The first and second coupling portions both extend outward from the central portion. The central portion has a first end and a second end. The reinforcing disk is concentric to the shaft and is attached to the shaft at a point between the first end and the second end of the central portion of the shaft. The first plurality of wings extend from the reinforcing disk to the first end of the central portion of the shaft. The second plurality of wings extend from the reinforcing disk to the second end of the central portion of the shaft. 
     In another aspect of the present disclosure, a conveyor pulley has a first end, second end, a centerpoint midway between the first end and second end and an axis which extends through the first end and second end. The pulley includes a first plurality of wings that extend from the centerpoint toward the first end and a second plurality of wings that extend from the centerpoint toward the second end. The axis of the pulley and each wing form an angle between about 30° and about 60°. 
     A further aspect of the present disclosure is directed to a belt conveyor system for transporting bulk materials. The system includes a conveyor belt and a tail section at which bulk material is loaded onto the conveyor belt. The tail section includes a tail pulley around which the conveyer belt is looped. The tail pulley includes a shaft, a reinforcing disk and a first and second plurality of wings. The shaft includes a central portion, a first coupling portion and a second coupling portion. The first and second coupling portions both extend outward from the central portion. The central portion has a first end and second end. The reinforcing disk is concentric to the shaft and is attached to the shaft at a point between the first end and the second end of the central portion of the shaft. The first plurality of wings extend from the reinforcing disk to the first end of the central portion of the shaft and the second plurality of wings extend from the reinforcing disk to the second end of the central portion of the shaft. The system also includes a head section at which bulk material is discharged from the conveyor belt. The head section includes a head pulley around which the conveyor belt is looped. 
     Another aspect of the present disclosure is directed to a method for transporting bulk material by use of a conveyor system. The system includes a conveyor belt, a tail section and a head section. The conveyor belt has an outer surface and an inner surface. Bulk material is loaded onto the outer surface of the conveyor belt at the tail section. The conveyor belt is looped around a tail pulley and a head pulley. The tail pulley includes a shaft, a reinforcing disk, a first and second plurality of wings and a plurality of contact bars. The shaft includes a central portion, a first coupling portion and a second coupling portion. The first and second coupling portions both extend outward from the central portion. The central portion has a first end and second end. The reinforcing disk is concentric to the shaft and is attached to the shaft at a point between the first end and the second end of the central portion of the shaft. The first plurality of wings extend from the reinforcing disk to the first end of the central portion of the shaft. A second plurality of wings extend from the reinforcing disk to the second end of the central portion of the shaft. Each contact bar is attached to a wing and contacts the inner surface of the conveyor belt upon rotation of the tail pulley. The tail pulley and head pulley are rotated to cause the conveyor belt to rotate and to cause bulk material to travel from the tail section to the head section. Bulk material is discharged from the conveyor belt at the head section. 
     Various refinements exist of the features noted in relation to the above-mentioned aspects of the present disclosure. Further features may also be incorporated in the above-mentioned aspects of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments of the present disclosure may be incorporated into any of the above-described aspects of the present disclosure, alone or in any combination. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conveyor pulley according to a first embodiment of the present disclosure; 
         FIG. 2  is a perspective view of the conveyor pulley with wings and contact bars removed for clarity; 
         FIG. 3  is an enlarged front view of the conveyor pulley with only one wing shown for clarity; 
         FIG. 4  is a front view of a wing of the conveyor pulley with a contact bar attached thereto; 
         FIG. 5  is a side view of the reinforcing disk of the conveyor pulley; 
         FIG. 6  is a perspective view of a contact bar according to a first embodiment of the present disclosure; 
         FIG. 7  is a perspective view of a contact bar according to a second embodiment of the present disclosure; 
         FIG. 8  is a perspective view of a contact bar according to a third embodiment of the present disclosure; 
         FIG. 9  is a front view of the conveyor pulley with only two wings shown for clarity; 
         FIG. 10  is a perspective view of the conveyor pulley with the contact bars removed for clarity; 
         FIG. 11  is a side view of the conveyor pulley with only one wing shown for clarity; 
         FIG. 12  is a perspective view of the conveyor pulley with a bushing attached thereto; 
         FIG. 13  is a perspective view of a conveyor pulley according to a second embodiment of the present disclosure; 
         FIG. 14  is a perspective view of a conveyor pulley according to a third embodiment of the present disclosure; 
         FIG. 15  is a perspective view of the conveyor pulley of  FIG. 14  with wings and contact bars removed for clarity; and 
         FIG. 16  is a schematic of a belt conveyor system according to a first embodiment of the present disclosure. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings. 
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , a pulley constructed in accordance with embodiments of the present disclosure is generally designated as “ 10 .” The pulley  10  includes a drum  14 , a first plurality of wings  4  and a second plurality of wings  8 . The wings  4 ,  8  have contact bars  3  attached thereto. The pulley  10  also includes a first hub  6  and a concentric reinforcing disk  15  discussed further below. A second hub (not shown) similar to the first hub  6  is included at the end of the pulley  10  opposite the first hub  6 . The pulley  10  has a direction of rotation R as shown in  FIG. 1 . 
     The pulley  10  is shown in  FIG. 2  with the wings  4 ,  8  and contact bars  3  not shown for clarity. The drum  14  has an imaginary central axis A about which it rotates and is composed of an annular wall  11 . The annular wall  11  has an inner surface  9  and outer surface  17  and a first end  19  and second end  20 . The annular wall  11  has an inner radius (not shown) that extends to the inner surface  9  and an outer radius R that extends to the outer surface  17 . The reinforcing disk  15  is attached to the outer surface  17  of the annular wall  11  (e.g., by welding) at a point between the first end  19  and second end  20 . The first end  19  and second end  20  define a centerpoint C. As shown in  FIG. 2 , the reinforcing disk  15  is attached at the centerpoint C of the drum  14 . In this regard, it should be understood that the reinforcing disk  15  may be attached to the drum  14  at positions other than the centerpoint C. Further in this regard, more than one reinforcing disk  15  may be attached to the drum  14  without departing from the scope of the present disclosure. The outer radius R of the annular wall  11  may be selected based on the application in which the pulley  10  is used and the desired rate at which bulk material is removed as appreciated by those of skill in the art. In various embodiments of the present disclosure, the radius R is at least about 3 inches, at least about 5 inches, at least about 10 inches, at least about 20 inches, at least about 35 inches or at least about 50 inches (e.g., from about 3 inches to about 72 inches or from about 5 inches to about 60 inches). 
     The first plurality of wings  4  ( FIG. 1 ) extend from the reinforcing disk  15  toward the first end  19  of the drum  14  and the second plurality of wings  8  extend from the reinforcing disk  15  toward the second end  20 . Referring now to  FIG. 3  in which only one wing is shown for clarity, the wing  8  has a lower end  22  and upper end  24 . At its lower end  22  the wing  8  extends to the second end  20  of the drum  14  and at its upper end  24  the wing extends beyond the second end  20 . In this regard, it should be understood that the wings  4 ,  8  of the pulley  10  may be arranged differently than as shown in the Figures. For example, the wings  4 ,  8  may extend fully beyond the ends  19 ,  20  of the drum  14  or the wings  4 ,  8  (including the lower ends  22  and/or upper ends  24 ) may not fully extend to the first and second ends  19 ,  20  of the drum. 
     A wing  8  of the present disclosure is shown in  FIG. 4 . A contact bar  3  is attached to the upper end  24  of the wing  8  (e.g., by welding). The lower end  22  is attached to the drum  14  ( FIG. 3 ). The wing  8  also includes an inner end  25  which contacts the reinforcing disk  15  ( FIG. 1 ) and an outer end  27  which extends toward a first end  19  or second end  20  of the drum  14 . The outer end  27  has an angular portion  29  that extends outward from the lower end  22  towards the upper end  24 . The outer end  27  also has an orthogonal portion  31  that is substantially perpendicular to the pulley axis A ( FIG. 2 ). The inner end  25  of the wing  8  is also substantially perpendicular to the pulley axis A. The inner end  25  and lower end  22  may form a rounded corner  23  (i.e., which may be notched rather than rounded) which provides clearance for welds formed between the reinforcing disk  15  and the drum  14  ( FIG. 2 ). 
     Both the lower end  22  and upper end  24  of the wing  8  are arcuate. The lower end  22  and upper end  24  may be characterized by substantially the same radius of curvature or different radius of curvature may be used. The radius of curvature of the lower end  22  is dependent on the angle at which the wing  8  is offset from the axis A of the pulley ( FIG. 9 ). The lower end  22  may have more than one radius of curvature (and may even contain a linear portion between the two radii of curvature) to conform the lower end  22  to the shape of the drum  14 . The lower end  22  may be tapered and one edge or both edges of the lower end  22  may contact the drum  14 . 
     The contact bar  3  has a radius of curvature substantially the same as the upper end  24  of the wing  8 . In this regard, it should be understood that the contact bar  3  as manufactured may be substantially linear and the contact bar may be manipulated (e.g., the contact bar may be bent) to conform to the curvature of the upper end  24  while it is attached to the upper end  24  of the wing  8 . The contact bar  3  may be arranged such that it curves downward near the reinforcing disk  15  ( FIG. 1 ) to cause the diameter of the pulley  10  to be substantially constant at the center portion of the pulley  10 . 
     In various embodiments of the present disclosure, the height of the wings (e.g., the distance between lower end  22  and upper end  24 ) may be at least about 1 inch and, in other embodiments, at least about 3 inches, at least about 6 inches or even at least about 9 inches (e.g., from about 1 inch to about 15 inches or from about 2 inches to about 12 inches). Generally, larger wing heights are used when a relatively larger drum  14  diameter is selected, as appreciated by those of skill in the art. 
     The contact bar  3  includes an overhang portion  30  that extends beyond the inner end  25  of the wing  8 . The overhang portion  30  may include a notch  32  which reduces wear on the conveyor belt. The overhang portion  30  may contact the reinforcing disk  15  ( FIGS. 1 and 2 ) at the outer radius of the reinforcing disk and, in some embodiments, is welded to the reinforcing disk. In this regard, it should be understood that the contact bar may contact the reinforcing disk without being attached (e.g., welded) thereto. The inner end  25  of the wing  8  may also be welded to the reinforcing disk  15 . 
     Attachment of the contact bars  3  and/or the wings  4 ,  8  to the reinforcing disk  15  ( FIG. 1 ) adds strength to the pulley and prevents the wings  4 ,  8  from folding and/or breaking from the drum  14 . It has been found that pulleys  10  that include a reinforcing disk  15  and drum  14  are generally stronger and more durable than pulleys which do not have a reinforcing disk but rather include strengthening gussets between the wings and/or that do not include a drum but rather attach the wings directly to the hub portion of the pulley. Locating the reinforcing disk  15  inward from the first end  19  and second end  20  (i.e., not locating one or more reinforcing disks at the first end  19  or second end  20 ) allows stray bulk material traveling on the underside of the conveyor belt to be more readily expelled from the pulley  10  upon contact with the pulley. As shown in the Figures, the pulley  10  does not include gussets (i.e., is “gusset-free”) and includes a central drum  14  which allows for a more robust construction. 
     Referring now to  FIG. 5 , the reinforcing disk  15  is generally an annulus having an inner radius R 2  and an outer radius R 3 . The reinforcing disk  15  is attached to the drum  14  ( FIG. 2 ) at the inner radius R 2 . The reinforcing disk  15  includes a plurality of notches  35  that generally conform to the size and shape of the contact bars  3  ( FIG. 1 ). As shown in  FIG. 6 , the contact bar  3  is generally round in shape and, for this reason, the notches  35  ( FIG. 5 ) are generally arcuate. It should be understood that the contact bars  3  may take any number of a variety of shapes including, for example, rectangular bars  3 ′ ( FIG. 7 ) and partial circles  3 ″ ( FIG. 8 ). 
     The wings  4 ,  8  of the pulley  10  may be attached to the pulley by placing the overhang portion  30  of the contact bar  3  ( FIG. 4 ) into a notch  35  of the reinforcing disk  15  ( FIG. 5 ). The inner end  25  ( FIG. 4 ) may be brought flush with the reinforcing disk  15  ( FIG. 2 ) and the lower end  22  ( FIG. 4 ) brought flush with the drum  14  ( FIG. 2 ). In this manner, the reinforcing disk  15  helps jig the pulley  10  during assembly and no other equipment is required (e.g., the pulley is “self-jigging”). In this regard, it should be understood that extraneous equipment (e.g., one or more jigs) may be used to brace the pulley  10  during assembly without departing from the scope of the present disclosure. 
     Referring now to  FIG. 9 , the wings  4 ,  8  of the pulley  10  are offset from the axis A of the pulley  10  and form an angle θ with axis A. Generally, each of wings  4 ,  8  form substantially the same angle with the axis A with the first plurality of wings  4  and the second plurality of wings  8  being symmetrically arranged (i.e., configured to generally face one another but in a spaced manner as described below). The angle θ formed between the wings and the axis A may be from about 10° to about 60° and is typically at least 15°. In other embodiments, the angle θ is from about 30° to about 60° or even from about 40° to about 60° which allows material to better be expelled from between the wings during operation and rotation of the pulley  10 . Offsetting the wings allows the pulley  10  to expel material as it rotates and helps the belt maintain its proper lateral position. 
     As can be seen from  FIG. 1 , the first plurality of wings  4  and the second plurality of wings  8  are generally arranged such that each wing is at a circumferential position different than each other wing. For instance and as shown in  FIG. 10  in which the contact bars are not shown for clarity, each wing  4  is attached to the reinforcing disk  15  at a different circumferential position than each wing  8  and, in particular, are attached at substantially equally spaced positions. Specifically, the lower end  22  ( FIG. 4 ) of each wing  4 ,  8  where it meets the reinforcing disk  15  (i.e., at the inner end  25 ) is at a circumferential position different than the lower ends  22  of each of the other wings  4 ,  8  and the upper end  24  of each wing  4 ,  8  where it meets the reinforcing disk  15  is at a circumferential position different than the upper ends  24  of each of the other wings  4 ,  8 . By spacing the circumferential position of each wing  4 ,  8  rather than having two wings  4 ,  8  attach to the reinforcing disk  15  at the same circumferential position so as to form a “V”, the number of contact points at which the contact bars ( FIG. 1 ) contact the conveyor belt at its center may be increased, which reduces wear of the conveyor belt. Further, the arrangement of the wings  4 ,  8  allows the pulley to more continually contact the belt during operation which reduces noise and vibration. 
     In this regard and as shown in  FIG. 11  in which all wings but one are removed for clarity, it should be understood that the inner end  25  of each wing  4 ,  8  attaches to the reinforcing disk  15  at an angle φ (the value of which depends on the angle θ described above) and, for this reason, a portion of the inner end  25  of each wing  4 ,  8  may overlap a portion of the inner end of another wing (e.g., the circumferential position of an upper end  24  of a wing where it attaches to the reinforcing disk  15  may be at or near the same circumferential position as the lower end  22  of another wing where it attaches to the reinforcing disk  15 ) without limitation. 
     The pulley  10  (shown throughout the Figures) has twenty-four (24) wings  4 ,  8  (twelve (12) corresponding to the first plurality of wings  4  and twelve (12) corresponding to the second plurality of wings  8 ); however, it should be understood that the pulley  10  may have more or less wings  4 ,  8  without limitation. For example and in several embodiments of the present disclosure, the pulley  10  has at least about 4 wings, at least about 8 wings, at least about 16 wings, at least about 24 wings, at least about 36 wings (e.g., from about 4 wings to about 48 wings or from about 16 wings to about 36 wings). In this regard it should be understood that the pulley  10  may include wings in a number other than as described herein, without limitation. 
     The pulley  10  includes two hubs  6  that are capable of being attached to a bushing  39  ( FIG. 12 ). A shaft (not shown) is inserted into the bushings  39  and rotated to cause rotation of the pulley  10  and the conveyor belt (not shown). The bushings  39  may be attached to the hubs  6  by the use of threaded sockets  42  ( FIG. 11 ) and bolts  44  ( FIG. 12 ). 
     The radius of the hubs  6  is less than the inner radius of the annular wall  11  of the drum  14  such that the hubs  6  may be inset within the drum  14 . The hubs  6  may be attached to the inner radius of the drum  14  by, for example, welding. In some alternative embodiments and as shown in  FIG. 13 , the radius of the hubs  6 ′ is substantially the same as the outer radius of the drum  14 ′ which allows the hubs  6 ′ to extend outward from the drum  14 ′. In this regard, it should be understood that in the pulley configuration shown in  FIG. 13 , the drum  14 ′ is commonly referred to as a “tube” in the art. However, as used herein, the terms “drum” and “tube” are interchangeable and use of either should not be viewed in a limiting sense. 
     In several embodiments of the present disclosure and as shown in  FIG. 14 , the pulley  10 ″ does not include a drum but rather the wings  4 ″,  8 ″ are directly attached to a shaft  63 ″. Referring now to  FIG. 15 , in which the wings  4 ″,  8 ″ and contact bars  3 ″ are not shown for clarity, the shaft  63 ″ includes a central portion  65 ″ to which the wings  4 ″,  8 ″ ( FIG. 14 ) are attached (e.g., by welding) and includes coupling portions  67 ″ which are used to rotate the pulley  10 ″. The shaft  63 ″ has an imaginary central axis A. The pulley  10 ″ includes a first end  19 ″ and a second end  20 ″ which correspond to the respective ends of the shaft  63 ″. The central portion  65 ″ has a first end  72 ″ and a second end  74 ″ to which the wings  4 ″,  8 ″ extend from the reinforcing disk  15 ″. The first end  72 ″ and second end  74 ″ of the central portion  65 ″ define a centerpoint C at which the reinforcing disk  15 ″ is attached to the shaft  63 ″. However, the reinforcing disk  15 ″ may be attached to the shaft  63 ″ at positions other than the centerpoint C. The inner radius of the reinforcing disk  15 ″ and the radius of the shaft  63 ″ at its central portion  65 ″ are substantially equal to facilitate attaching the disk  15 ″ to the shaft  63 ″. 
     The coupling portions  67 ″ of the pulley  10 ″ generally extend outward from the central portion  65 ″ and outward from the wings  4 ″,  8 ″ ( FIG. 14 ) and may have a diameter less than central portion  65 ″. The shaft  63 ″ may also have one or more diameter-reducing portions  76 ″,  78 ″ which are sloped or curved to gradually reduce the diameter from that of the central portion  65 ″ to the respective diameter of the coupling portions  67 ″. In some embodiments, the diameter of the coupling portions  67 ″ and the central portion  65 ″ are substantially the same. In this regard, the shaft  63 ″ may have additional portions that have a diameter different from the central portion  65 ″ and/or coupling portions  67 ″ without limitation. 
     The pulley  10 ″ shown in  FIGS. 14 and 15  is well suited for high tension applications and, in particular, applications in which a smaller diameter pulley is desirable (e.g., as in some mining applications). By eliminating the tube, (e.g., by directly attaching the wings  4 ″,  8 ″ to the shaft  63 ″) the pulley  10 ″ maintains its strength and durability even at smaller diameters. 
     It should be understood that the components of the pulley  10  described above may be constructed of any suitable material as appreciated by those of skill in the art. Typically, the components are composed of metal (e.g., carbon steel or stainless steel). The pulley  10  may also include an amount of lagging (e.g., thermoplastic-based material that assists in increasing the coefficient of friction between the pulley and conveyor belt) on the surface of the contact bars  3 . 
     The pulley  10  described in the various embodiments above may be used in a belt conveyor system  50  for transporting bulk materials as shown schematically in  FIG. 16 . The conveyor system  50  has a tail section  55  at which bulk material is loaded and a head section  60  at which bulk material is discharged, typically by force of gravity. The conveyor system  50  includes a conveyor belt  52  which supports the bulk material and which rotates around a tail pulley  57  and a head pulley  58 . The bulk material is supported on an outer surface  51  of the conveyor belt  52 . An inner surface  59  of the conveyor belt contacts the tail pulley  57  and the head pulley  58 . The tail pulley  57  may be substantially the same as described in one or more embodiments above so as to allow bulk material that has fallen onto the inner surface  59  of the conveyor belt to be more readily ejected from the belt system (e.g., by traveling laterally to the direction of the belt upon contact with the tail pulley  57 ). In this regard, the head pulley may optionally be configured as described above. The head pulley  58  may drive the conveyor belt system  50  (e.g., motor rotation); however, it should be understood that alternatively the tail pulley  57  may drive the system. Further in this regard, the conveyor system  50  may contain pulleys other than as shown (e.g., snub pulleys, bend pulleys, take-up pulleys and the like) which may optionally drive the belt system and/or which may optionally be configured as described above or according to conventional configurations. It should also be understood that the conveyor system  50  is shown for illustration and is not drawn to scale. 
     In this regard, the conveyor system  50  of  FIG. 16  described above may be used in various methods for transporting bulk material. According to several embodiments, bulk material is loaded onto the outer surface  51  of the conveyor belt  52  at the tail section  55 . The tail pulley  57  and head pulley  58  are rotated to cause the conveyor belt to rotate and to cause bulk material to travel from the tail section  55  to the head section  60  of the conveyor system  50 . Bulk material is discharged from the conveyor belt at the head section  60 . In this regard, it should be understood that the term “rotate” as used herein does not imply that that the respective pulley that is rotated is a drive pulley. Rather, rotation may be caused by movement of the conveyor belt  50  which may be driven by any other of the pulleys used in the conveyor system and the term “rotate” should not be considered in a limiting sense. 
     When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     As various changes could be made in the above apparatus and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying figures shall be interpreted as illustrative and not in a limiting sense.