Abstract:
A metering apparatus for distributing an agricultural product in a field has a meterbox configured for association with a hopper for receiving agricultural product from the hopper. A rotatable metering element is disposed within a chamber in the meterbox, and the rotating metering element is configured to deliver the agricultural product at a regulated rate from the hopper through the chamber to a product distribution line. Delivery of the agricultural product to the product distribution line may be selectively stopped by a reversibly inflatable seal between the metering element and an outlet to the distribution line, a reversible seal formed by contact between the metering element and an inlet from the hopper to the chamber, or a disengagement structure for disengaging the agricultural product from the metering element while the metering element continues to rotate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/972,494 filed Mar. 31, 2014, the entire contents of which is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to metering apparatuses for agricultural product. 
     BACKGROUND OF THE INVENTION 
     Implements for distributing agricultural product (e.g. seed, fertilizer, etc.) in a field are generally towed behind a tractor or other vehicle. Such implements include one or more ground engaging tools for opening the ground to provide a path in which the agricultural product is deposited. Deposition is accomplished by a system for distributing the agricultural product generally from a single large bin through various lines and ports to be finally deposited on the ground through an outlet port. Following the deposition of the agricultural product, packers cover the deposited agricultural product with soil. 
     An air cart is one system for distributing agricultural product. An air cart comprises one or more large bins for holding one or more different types of agricultural product, an airflow source (e.g. a fan) and lines or hoses through which agricultural product is carried by the airflow to outlets located at or near the ground engaging tools of the implement. The product passes through the outlet to be deposited on the ground. There are typically a plurality of lines, hoses and ports, one outlet port associated with each ground engaging tool in order to apply product in a regular pattern to large areas of land in a single pass of the implement. 
     In air carts, proper metering of agricultural product into the airflow is desired to regularize the amount of product delivered to the outlets over time in order to reduce over- or under-deposition of the product in a particular area. Air carts traditionally employed single auger hoppers in which one very large (1-2 feet long) rotating auger distributed agricultural product from the hopper into a single airstream. Such arrangements are still used today by some manufacturers, for example Amity. Single auger air carts suffer from a number of problems. First, either the auger is on or off so agricultural product is either delivered across the entire implement or not delivered at all anywhere on the implement. Thus, fine control over sectional metering is impossible. Second, agricultural product must be metered into an initial large 5″ line, and then split into 2.5″ lines followed by another split into 1″ lines. This creates more complexity as secondary splitters are required and provides less control in how product is transported around the distribution system. Third, it is impossible to distribute more than one kind of product at the same time. 
     Fine sectional control is desirable because passage of the implement over soil that has already received agricultural product (e.g. the headland) would result in waste of product; therefore, it is desirable to shout off distribution to parts of the implement that are passing over such soil. In an effort to solve this problem, metering apparatuses are preferably equipped with sectional shutoff capabilities to selectively stop deposition of product at parts of the implement passing over already serviced soil. Metering apparatuses for this purpose are known in the art, for example as disclosed in US 2012/0325131 published Dec. 27, 2012, U.S. Pat. No. 8,132,521 issued Mar. 13, 2012, U.S. Pat. No. 8,141,504 issued Mar. 27, 2012 and U.S. Pat. No. 8,196,534 issued Jun. 12, 2012, the entire contents of all of which are herein incorporated by reference. Such metering apparatuses generally involve a meter roller assembly in which a plurality of meter rollers is rotated on a common shaft, the rollers rotating around a transverse axis relative to the motion of the distribution implement. In such an arrangement, sectional control of the meter rollers to prevent distribution of product to certain parts of the implement is problematic. Complicated clutching mechanisms or inefficient gating mechanisms have all been used as described in the aforementioned prior art apparatuses. 
     Recent developments have provided metering apparatuses for distributing an agricultural product having a plurality of metering elements coupled to a drive input, each of the metering elements rotating around different axes of rotation. Examples are described in commonly owned U.S. Ser. No. 14/198,584 filed Mar. 5, 2014 and in U.S. Pat. No. 8,434,416 issued May 7, 2013, the entire contents of both of which are herein incorporated by reference. Sectional control may be accomplished by shutting off flow of agricultural product at individual metering elements through the use of clutches or individually driven metering elements. 
     However, there remains a need for metering apparatuses for agricultural product having different means for sectional control of product distribution in a field. 
     SUMMARY OF THE INVENTION 
     There is provided a metering apparatus for distributing an agricultural product, comprising: a meterbox configured for association with a hopper for receiving agricultural product from the hopper; a rotatable metering element disposed within a chamber in the meterbox, the rotating metering element configured to deliver the agricultural product at a regulated rate from the hopper through the chamber to a product distribution line; and, stopping means for selectively stopping delivery of the agricultural product to the product distribution line, the stopping means comprising a reversibly inflatable seal between the metering element and an outlet to the distribution line, a reversible seal formed by contact between the metering element and an inlet from the hopper to the chamber, or a disengagement structure for disengaging the agricultural product from the metering element while the metering element continues to rotate. 
     There is further provided an agricultural product distribution system comprising a metering apparatus of the present invention. 
     The metering apparatus and distribution system have a longitudinal axis in the direction of forward (or backward) motion of an agricultural product distribution implement as it is being towed across the ground. The longitudinal axis runs from front to rear (or rear to front) of the metering apparatus and distribution system. The metering apparatus and distribution system have a transverse axis that is perpendicular to the longitudinal axis and runs side to side (left to right or right to left) of the metering apparatus and distribution system. 
     The metering apparatus comprises a rotatable metering element disposed within a chamber in the meterbox. Rotatable metering element may include, for example, belt meters, meter rollers and the like. Meter rollers may include smooth output rollers, pegged output rollers, fluted output rollers, high output rollers, etc. 
     There may be one or a plurality of the metering elements in the chamber arranged in one or a plurality of rows. The metering elements may be driven on a common shaft, or one or more of the metering elements may be driven on one or more separate shafts. In one embodiment, all of the metering elements may be driven on a single shaft. The number of metering elements per meterbox is preferably three or more, four or more or five or more. One or more, two or more or three or more rows of metering elements may be used. The numbers will depend to an extent on the size of the distribution implement. From 1 to 5 rows and from 5 to 15 metering elements per row are preferred. For many applications, 1 row with from 6 to 12 metering elements in one meterbox is suitable. 
     One or more drive inputs may be used to drive rotation of the metering elements. The drive input may be derived from any suitable source of mechanical power, for example a motor or motors. Motors include electric motors, hydraulic motors, stepper motors, internal combustion engines, etc. In some cases the power take-off from a towing vehicle may be used to drive the metering elements. In other cases, a ground driven wheel may be used to provide rotational movement of the drive input by virtue of forward travel of the implement along the field. The drive input may be coupled to the metering elements by any coupling means suitable for the type of drive input and the arrangement of the metering elements on drive shafts. Couplings include, for example, belt on pulley, chain on sprocket, directly linked drive shaft, etc. 
     The metering elements may be disposed in the meterbox collectively in a single chamber, individually within individual chambers or some combination thereof. The chamber may comprise one or more openable and closeable access ports for permitting access into the chamber without removing any metering element. Access permits servicing the metering apparatus without necessarily needing to take the time to remove the metering elements. In some embodiments, the access ports may also permit individual servicing of each metering element, for example individual cleaning or, if needed or desired, individual change out of a metering element without needing to disturb the other metering elements. 
     The meterbox may further comprise an inlet for receiving agricultural product from the hopper and an outlet for delivering metered product to a product distribution line, for example an air distribution line in the case of air carts. There may be a plurality of inlets and/or outlets. Each metering element may be associated with one inlet, or one inlet may provide product to more than one metering element. Each metering element may be associated with one outlet, one metering element may be associated with more than one outlet, one outlet may be associated with more than one metering element of some combination thereof. The meterbox may be separated from or integrated within the hopper. The hopper and/or meterbox may be equipped with other standard features, for example, covers, canopies and/or agitator bars. 
     The stopping means permits selective delivery of the agricultural product to the product distribution line. Being able to select whether the product distribution line will receive product at any given time permits sectional control of product delivery to the field. It is desirable to avoid multiple applications of agricultural product to the same area of the field, both for reducing product waste and also for improving product performance by providing it at the correct dosage. Furthermore, where the metering apparatus comprises a plurality of metering elements, it is possible to configure the stopping means to prevent delivery of product from one or more metering elements but not others. This permits an operator to sequentially or otherwise selectively prevent product delivery from individual or groups of metering elements when approaching an irregular boundary, such as a water hole, in a field while towing the distribution implement. Because the implement must be towed to avoid the irregular boundary, parts of the implement will be towed over areas of the field in which agricultural product has already been deposited. By selectively determining the rate of application of agricultural product across a width of the distribution implement, the present invention permits control over where the agricultural product will be deposited, thus greatly reducing product waste and improving distribution patterns of the product in the field. 
     The stopping means may comprise a reversibly inflatable seal between the metering element and an outlet to the distribution line. The reversibly inflatable seal may comprise a surface that engages an inner surface of the chamber when the inflatable seal is inflated to block passage of the agricultural product from the chamber to the outlet. The surface of the inflatable seal may comprise a protrusion, and the protrusion may abut a floor of the chamber proximate the outlet when the inflatable seal is inflated. The inflatable seal may comprise a base secured to a wall of the chamber. When there is a plurality of metering elements, there may be a single inflatable seal for all the metering elements, one inflatable seal for each metering element or one inflatable seal for a few of the metering elements and other inflatable seals for the other metering elements. For individual control over product flow from individual metering element, one inflatable seal per metering element is preferred. Furthermore, the metering apparatus may comprise one or more conduits for recycling agricultural product from the chamber to the hopper when the inflatable seal is inflated. 
     The stopping means may comprise a reversible seal formed by contact between the metering element and an inlet from the hopper to the chamber. The seal may be formed and unformed by moving the metering element between a lowered unsealing position and a raised sealing position. The movement may involve a simple translation of the metering element up and down, or may involve a pivoting motion of the metering element. In one embodiment, the metering element comprises a meter roller. The meter roller may comprise an arcuate surface that protrudes into the hopper through the inlet when the meter roller is in the raised sealing position, whereby the arcuate surface abuts the hopper on each side of the inlet to seal the inlet to prevent flow of agricultural product from the hopper to the chamber. The meter roller may be pivotable between the raised sealing position and the lowered unsealing position to open and close a gap between the arcuate surface and the hopper at only one side of the inlet. The gap has a size that may be adjusted to vary the rate at which the agricultural product is delivered to the product distribution line. In another embodiment, the metering element comprises a belt meter. The belt meter may comprise an endless belt having an outer surface that abuts the hopper on each side of the inlet when the belt meter is in the raised sealing position to seal the inlet and prevent flow of agricultural product from the hopper to the chamber. The belt meter may be pivotable between the raised sealing position and the lowered unsealing position to open and close a gap between the endless belt and the hopper at one side of the inlet and to downwardly incline the belt meter toward the one side of the inlet when the belt meter is in the lowered unsealing position. The gap has a size that may be adjusted to vary the rate at which the agricultural product is delivered to the product distribution line. 
     The stopping means may comprise a disengagement structure for disengaging the agricultural product from the metering element while the metering element continues to rotate. The disengagement structure permits disengagement of the agricultural product from the metering element while the metering element continues to rotate; however, in addition to using the disengagement structure, the metering element may also be stopped, if desired, to further ensure that metering of the agricultural product is stopped. 
     In one embodiment, the disengagement structure may comprise moving the agricultural product away from the metering element. Moving the agricultural product may involve lowering, raising and/or laterally translating a structure that contains the agricultural product. For example, the chamber may comprise a chamber floor and the disengagement structure may comprise the chamber floor movable between a product engaging position and a product disengaging position. Preferably, the product engaging position comprises a raised position and the product disengaging position comprises a lowered position. One of a variety of arrangements may be utilized to facilitate moving the chamber floor. In one arrangement, the chamber may comprise a trough portion secured by a hinge to the hopper or an immovable part of the meterbox, whereby the trough portion may comprise the chamber floor and the trough portion may swing on the hinge between a raised and lowered positions. The meterbox may comprise an inclined portion having a lip over which the agricultural product flows to reach an outlet to the product distribution line, and an inlet guard depending down from the hopper into the chamber such that an end of the inlet guard is at a level low enough to prevent continuous agricultural product flow over the lip. In one embodiment, the inlet guard is at the same level as or lower than the lip. The chamber floor may comprise an inclined portion that slidably abuts the inclined portion of the meterbox to form a seal to prevent agricultural product from exiting the chamber without flowing over the lip. In another arrangement, the chamber may comprise a trough portion secured to a translatable product conduit. The product conduit may be configured to permit agricultural product to flow from the hopper to the trough portion. An actuator, for example a hydraulic cylinder, an electrical actuator, a spring or a combination thereof, may be utilized to effect translation of the product conduit and trough portion. In one embodiment, a hydraulic actuator may be utilized to selectively translate the product conduit and trough portion, while a compression spring may be utilized at the same time to continuously bias the product conduit and trough portion toward the product engaging position. The conduit may be translated in any direction, for example vertically, laterally or at an angle to the lateral and/or vertical directions. Preferably, the conduit is translated vertically, or at an angle of up to 45° to the vertical and horizontal directions. 
     In another embodiment, the metering element may comprise a meter roller and the disengagement structure may comprise the meter roller movable between a lowered product engaging position and a raised product disengaging position. The chamber may comprise a chamber floor comprising an inclined portion having a lip over which the agricultural product flows to reach an outlet to the product distribution line, and an inlet guard depending down from the hopper into the chamber such that an end of the inlet guard is at a level low enough to prevent continuous agricultural product flow over the lip. In one embodiment, the inlet guard is at the same level as or lower than the lip. Raising and lowering of the meter roller may involve a simple translation of the meter roller up and down, or may involve a pivoting motion of the meter roller. The meter roller may be pivoted between the raised and lowered positions in any suitable fashion, for example by an actuator (e.g. a linear actuator or a hydraulic cylinder). The meter roller may be connected to a gear and the gear intermeshed with a driven sprocket. Driving the sprocket drives the meter roller. Where more than one meter roller is present, one or more drive axles may be used to drive the sprockets and hence the meter rollers. 
     Agricultural product may include, for example, seed, fertilizer, pesticide, etc. Different types of agricultural product may be distributed separately or at the same time. It is a particular advantage that one implement can have multiple hoppers, each hopper containing different agricultural product and equipped with metering elements arranged in accordance with the present invention for simultaneous distribution of different agricultural product while having separate sectional control over the distribution of each type of agricultural product. 
     The metering apparatus may be used in conjunction with an agricultural product distribution system, for example an air cart where airflow is used to transport agricultural product through various air lines (e.g. hoses) and ports to outlet ports through which the product is deposited in soil. In such an air cart arrangement, the metering apparatus meters agricultural product into an airstream that carries the product to other parts of the distribution implement. Each airstream is generally carried in separate air lines. There may be one or more than one metering element per airstream, so a single airstream may receive product from one or more than one metering element. 
     Further features of the invention will be described or will become apparent in the course of the following detailed description. It will be apparent that certain features while described in the context of one embodiment are also applicable in the context of any other embodiment, and that the detailed description is meant to illustrate particular embodiments and not limit the applicability of individual features only to the embodiments in which the features are described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be more clearly understood, embodiments thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1A  depicts a first embodiment of a metering apparatus where flow of agricultural product to an air distribution line is blocked by an inflatable balloon between a meter roller and an outlet to the air distribution line. 
         FIG. 1B  depicts the metering apparatus of  FIG. 1A  where the inflatable balloon is deflated to permit flow of agricultural product to the air distribution line. 
         FIG. 2A  depicts a perspective view of a second embodiment of a metering apparatus where flow of agricultural product to an air distribution line is blocked by a meter roller protruding into a hopper and forming a seal with the hopper at an inlet from the hopper into a metering chamber. 
         FIG. 2B  depicts a side view of  FIG. 2A . 
         FIG. 2C  depicts an end view of  FIG. 2A . 
         FIG. 2D  depicts the metering apparatus of  FIG. 2A  where the meter roller has been pivoted away from the inlet to permit flow of agricultural product from the hopper to the metering chamber and then to the air distribution line. 
         FIG. 2E  depicts a side view of  FIG. 2D . 
         FIG. 2F  depicts an end view of  FIG. 2D . 
         FIG. 3A  depicts a perspective view of a third embodiment of a metering apparatus where flow of agricultural product to an air distribution line is blocked by a belt of a belt meter forming a seal with a hopper at an inlet from the hopper into a metering chamber. 
         FIG. 3B  depicts a side view of  FIG. 3A . 
         FIG. 3C  depicts a top view of  FIG. 3A . 
         FIG. 3D  depicts the metering apparatus of  FIG. 3A  where the belt meter has been pivoted away from the inlet to permit flow of agricultural product from the hopper to the metering chamber and then to the air distribution line. 
         FIG. 3E  depicts a side view of  FIG. 3D . 
         FIG. 3F  depicts a top view of  FIG. 3D . 
         FIG. 4A  depicts a perspective view of a fourth embodiment of a metering apparatus where flow of agricultural product to an air distribution line is prevented by lowering the agricultural product in a metering chamber away from a continuously turning meter roller to disengage the agricultural product from the meter roller. 
         FIG. 4B  depicts a side view of  FIG. 4A . 
         FIG. 4C  depicts an end view of  FIG. 4A . 
         FIG. 4D  depicts the metering apparatus of  FIG. 4A  where the agricultural product is raised in the metering chamber to engage the meter roller to permit metering of the agricultural product to the air distribution line. 
         FIG. 4E  depicts a side view of  FIG. 4D . 
         FIG. 4F  depicts an end view of  FIG. 4D . 
         FIG. 5A  depicts a perspective view of a fifth embodiment of a metering apparatus where flow of agricultural product to an air distribution line is prevented by raising a continuously rotating meter roller away from the agricultural product in a metering chamber to disengage the meter roller from the agricultural product. 
         FIG. 5B  depicts a side view of  FIG. 5A . 
         FIG. 5C  depicts a top view of  FIG. 5A . 
         FIG. 5D  depicts the metering apparatus of  FIG. 5A  where the meter roller is lowered in the metering chamber to engage the meter roller with the agricultural product to permit metering of the agricultural product to the air distribution line. 
         FIG. 5E  depicts a side view of  FIG. 5D . 
         FIG. 5F  depicts a top view of  FIG. 5D . 
         FIG. 6A  depicts a perspective view of a sixth embodiment of a metering apparatus where flow of agricultural product to an air distribution line is prevented by pivoting a continuously rotating meter roller to raise the meter roller away from the agricultural product in a metering chamber to disengage the meter roller from the agricultural product. 
         FIG. 6B  depicts an end view of the metering apparatus of  FIG. 6A . 
         FIG. 7A  depicts a perspective view of a seventh embodiment of a metering apparatus where flow of agricultural product to an air distribution line is prevented by moving the agricultural product in a metering chamber away from a meter roller to disengage the agricultural product from the meter roller. 
         FIG. 7B  depicts a side view of  FIG. 7A  in a configuration for permitting product flow to the air distribution line. 
         FIG. 7C  depicts a side view of  FIG. 7A  in a configuration for preventing product flow to the air distribution line. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to  FIG. 1A  and  FIG. 1B , a metering apparatus  100  is shown in which flow of agricultural product from a hopper  150  to an air distribution line  190  may be blocked by an inflatable balloon  105  between a meter roller  110  and an outlet  130  to the air distribution line  190 . The metering apparatus  100  comprises the meter roller  110 , in this case a pegged meter roller although any suitable meter roller (e.g. a smooth roller, fluted roller or high output roller) may be employed, disposed within a metering chamber  106  of a meterbox  107 . The metering chamber  106  is in communication with the hopper  150  via an inlet  115  so that the agricultural product in the hopper  150  can flow into the metering chamber  106 . The agricultural product collects on a floor  109  of the metering chamber  106  and engages with the meter roller  110 . As seen in  FIG. 1B , when the balloon  105  is deflated, rotation of the meter roller  110 , in this case clockwise rotation, meters the agricultural product at a regulated rate up and over a lip  112  proximate an end of an inclined portion  113  of the floor  109  to exit the metering chamber  106  through the outlet  130  into the air distribution line  190 , which carries the agricultural product to product application outlets for distribution in a field. 
     When it becomes desirable to cut off flow of the agricultural product to the air distribution line  190 , the balloon  105  may be inflated by directing air flow (or some other gaseous or liquid medium) into the balloon  105 . Air for inflating the balloon may be provided by the same or different source as the air for the air distribution line. For example, an air compressor or other type of compressive device may be provided to inflate the balloon with any suitable gaseous or liquid medium. Decompression may be accomplished by letting the medium vent into the environment. The balloon naturally retracts and decompresses to its deflated state. 
     The balloon  105  comprises an external knob  104  that engages and seals against the lip  112  of the floor  109  of the metering chamber  106  when the balloon is inflated thereby sealing the outlet  130  away from the meter roller  110  so that the agricultural product cannot be metered through the outlet  130  even though the meter roller  110  continues to rotate. Deflating the balloon  105  disengages the knob  104  from the lip  112  to once again permit the agricultural product to flow over the lip  112  through the outlet  130  and into the air distribution line  190 . 
     The balloon  105  is made from a sufficiently flexible material, for example an elastomer such as natural or synthetic rubber, to permit inflation and deflation of the balloon. The knob  104  may be made of the same or different material as the balloon  105 . The knob  104  is preferably made of sufficiently flexible material to form a suitable seal with the lip  112 . Both the balloon  105  and the knob  104  are preferably made of sufficient durable material to be able to resist the flow of agricultural product from a constantly rotating meter roller and to withstand repeated inflations and deflations. 
     The balloon  105  may be secured in the metering chamber  106  by attaching base  103  of the balloon to a wall of the metering chamber  106 . When the balloon  105  is inflated as shown in  FIG. 1A , agricultural product moved as a result of the meter roller  110  constantly rotating may travel up the side of the balloon  105 . To prevent agricultural product from overtopping the balloon  105  and falling down the other side, a duct may be provided to recycle the agricultural product back to the hopper  150  from the metering chamber  106 . Further, a pressure equalizing duct  155  is provided for venting out air from above the meter roller  110  when the air distribution fan is turned off. Furthermore, to be able to access the inside of the metering chamber  106  to effect maintenance, repair, cleaning or the like of the metering apparatus, a removable gate  170  may be included over an aperture in one of the walls of the metering chamber  106 . Removing the removable gate  170  provides access to the inside of the metering chamber  106  through the aperture in the wall of the metering chamber  106 . 
     With reference to  FIG. 2A ,  FIG. 2B ,  FIG. 2C ,  FIG. 2D ,  FIG. 2E  and  FIG. 2F , a metering apparatus  200  is shown in which flow of agricultural product  220  from a hopper  250  to an air distribution line (not shown) may be blocked by a meter roller  210  protruding into the hopper  250  and forming a seal with the hopper  250  at an inlet  215  from the hopper  250  into a metering chamber  206 . The metering apparatus  200  comprises the meter roller  210 , in this case a smooth surfaced meter roller although any suitable meter roller (e.g. a pegged roller, fluted roller or high output roller) may be employed, disposed within the metering chamber  206  of a meterbox  207 . The metering chamber  206  is in communication with the hopper  250  via the inlet  215  so that the agricultural product  220  in the hopper  250  can flow into the metering chamber  206  when the meter roller  210  does not block the inlet  215 . The hopper  250  comprises first and second roller plates  251 , 252  having end surfaces  253 , 254 , respectively, that are configured to abut or almost abut the arcuate outer surface  211  of the meter roller  210 . The roller plates  251 , 252  are secured to an inside wall of the hopper  250  and flank the inlet  215 , protruding partially into the inlet aperture  215 . When the meter roller  210  is in a closed position a seen in  FIG. 2A  and  FIG. 2B , the end surfaces  253 , 254  of the roller plates  251 , 252 , respectively, are abutting or in close proximity to the arcuate surface  211  of the meter roller  210  so that there is insufficient space between the arcuate surface  211  and the end surfaces  253 , 254  to permit agricultural product  220  from entering the metering chamber  206  from the hopper  250 . At the same time, the arcuate surface  211  may not actually touch the end surfaces  253 , 254  or may only touch slightly so that the meter roller  210  can continue to rotate or to accommodate surface features on the meter roller, e.g. pegs, in which case a brush may be disposed at the inlet to prevent product from flowing when the meter roller is in the closed position. 
     To open the inlet as shown in  FIG. 2D  and  FIG. 2E , the meter roller  210  may be pivoted downward by rotation of a driven sprocket  265  geared to a gear  217  on a roller shaft  213  on which the meter roller  210  is mounted. Pivoting of the meter roller  210  causes the arcuate surface  211  to move away from the end surface  253  of the first plate  251  thereby opening a gap  219  between the arcuate surface  211  of the meter roller  210  and the end surface  253  of the first plate  251 . The gap  219  permits the agricultural product  220  from the hopper  250  to enter the metering chamber  206  and to be metered down at a regulated rate to outlet  230  at the bottom of the metering chamber  206  by the rotating meter roller  210 , which in this case is rotating clockwise. Further, varying the width of the gap  219  provides an opportunity to change the rate of metered product, permitting changes for various sizes and rates of agricultural product in addition to being able to vary the speed of the meter roller  210 . The outlet  230  is in communication with the air distribution line, which carries the agricultural product  220  to product application outlets for distribution in a field. The sprocket  265  and shaft  213  are configured so that pivoting of the meter roller  210  does not appreciably change the distance between the arcuate surface  211  and the end surface  254  of the second plate  252 . Reversing the pivoting motion of the meter roller  210  causes the gap  219  to close between the arcuate surface  211  and the end surface  253  of the first plate  251  thereby preventing flow of the agricultural product  220  from the hopper  250  to the metering chamber  206 . 
     With reference to  FIG. 3A ,  FIG. 3B ,  FIG. 3C ,  FIG. 3D ,  FIG. 3E  and  FIG. 3F , a metering apparatus  300  is shown in which flow of agricultural product  320  from a hopper  350  to an air distribution line (not shown) may be blocked by an endless belt  311  of a belt meter  310  that may form a seal with the hopper  350  at an inlet  315  from the hopper  350  into a metering chamber  306 . The metering apparatus  300  comprises the belt meter  310 , in this case a smooth belt although any suitable belt (e.g. a pegged belt or fluted belt) may be employed, disposed within the metering chamber  306  of a meterbox  307 . The metering chamber  306  is in communication with the hopper  350  via the inlet  315  so that the agricultural product  320  in the hopper  350  can flow into the metering chamber  306  when the endless belt  311  of the belt meter  310  does not block the inlet  315 . The hopper  350  comprises first and second belt plates  351 , 352  having end surfaces  353 , 354 , respectively, that are configured to abut or almost abut the outer surface of the endless belt  311  of the belt meter  310 . The belt plates  351 , 352  are secured to an inside wall of the hopper  350  in the inlet  315  leaving a sufficiently sized aperture for the agricultural product  320  to flow through the inlet  315 . When the belt meter  310  is in a closed position a seen in  FIG. 3A  and  FIG. 3B , the end surfaces  353 , 354  of the belt plates  251 , 252 , respectively, are abutting or in close proximity to the outer surface of the endless belt  311  of the belt meter  310  so that there is insufficient space between the outer surface of the endless belt  311  and the end surfaces  353 , 354  to permit agricultural product  320  from entering the metering chamber  306  from the hopper  350 . At the same time, the outer surface of the endless belt  311  may not actually touch the end surfaces  353 , 354  or may only touch slightly so that the endless belt  311  can continue to rotate or to accommodate surface features on the endless belt, e.g. pegs, in which case a brush may be disposed at the inlet to prevent product from flowing when the belt meter is in the closed position. 
     The belt meter  310  comprises the endless belt  311  looped around driven pulley  323  and idler pulley  324 . The driven pulley  323  is mounted on drive shaft  313  and the idler pulley  324  is mounted on idler shaft  314 . The inside surface of the endless belt  311  and the outside surface of the pulleys  323 , 324  may comprise mated engagement elements  326 , 327  that engage each other to assist with preventing slippage of the endless belt  311  when the endless belt  311  is being driven. Slippage would be problematic for the regulated metering of agricultural product  320  by the belt meter  310 . In alternate embodiments, the shaft  314  may be driven and the shaft  313  may be an idler or both shafts may be driven. 
     To open the inlet as shown in  FIG. 3D  and  FIG. 3E , the belt meter  310  may be pivoted downward about driven shaft  313 . Pivoting of the belt meter  310  in this way causes the outside surface of the endless belt  311  to move away from the end surface  353  of the first plate  351  thereby opening a gap  319  between the outside surface of the endless belt  311  and the end surface  353  of the first plate  351 . In addition, the belt meter  310  becomes downwardly inclined toward the side of the inlet  315  at which the gap  319  has opened. The gap  319  permits the agricultural product  320  from the hopper  350  to flow through the inlet  315  on to the endless belt  311 , which in this case is rotating clockwise, to be metered at a regulated rate by the belt meter  310  through the metering chamber  306  down to outlet  330  at the bottom of the metering chamber  306 . Further, varying the size of the gap  319  provides an opportunity to change the rate of metered product, permitting changes for various sizes and rates in addition to being able to vary the speed of the belt meter  310 . The outlet  330  is in communication with the air distribution line, which carries the agricultural product  320  to product application outlets for distribution in a field. Reversing the pivoting motion of the belt meter  310  causes the gap to close between the outer surface of the endless belt  311  and the end surface  353  of the first plate  351  thereby preventing flow of the agricultural product  320  from the hopper  350  to the metering chamber  306 . 
     With reference to  FIG. 4A ,  FIG. 4B ,  FIG. 4C ,  FIG. 4D ,  FIG. 4E  and  FIG. 4F , a metering apparatus  400  is shown in which flow of agricultural product  420  from a hopper  450  to an air distribution line (not shown) may be stopped from entering the air distribution line by lowering the agricultural product  420  in a metering chamber  406  away from a continuously turning meter roller  410  to disengage the agricultural product  420  from the meter roller  410 . The metering apparatus  400  comprises the meter roller  410 , in this case a pegged meter roller although any suitable meter roller (e.g. a smooth roller, fluted roller or high output roller) may be employed, mounted on shaft  417  and disposed within the metering chamber  406  of a meterbox  407 . The metering chamber  406  is in communication with the hopper  450  via the inlet  415  so that the agricultural product  420  in the hopper  450  can flow into the metering chamber  406 . The agricultural product  420  collects on a floor  409  of the metering chamber  406  and engages with the meter roller  410 . As seen in  FIG. 4D  and  FIG. 4E , when the floor  409  of the metering chamber  406  is in a raised position, rotation of the meter roller  410 , in this case clockwise rotation, meters the agricultural product  420  at a regulated rate up and over a lip  412  proximate an end of an inclined portion  413  of the meterbox  407  to exit the metering chamber  406  through an outlet  430  into the air distribution line, which carries the agricultural product  420  to product application outlets for distribution in a field. 
     When it becomes desirable to cut off flow of the agricultural product  420  to the air distribution line, the floor  409  of the metering chamber  406  is lowered proximate the lip  412  as seen in  FIG. 4A  and  FIG. 4B . The metering chamber  406  comprises a trough portion  401 , the trough portion  401  comprising side walls, the floor  409  and a back wall  402  hingedly secured to the hopper  450  (or an immovable part of the meterbox  407 ) by a hinge  427  proximate the inlet  415 . Allowing the trough portion  401  to swing counter-clockwise around the hinge  427  (in the configuration depicted in  FIG. 4D  and  FIG. 4E ) causes the floor  409  to become lower proximate the lip  412  as seen in  FIG. 4A  and  FIG. 4B . Because the floor  409  proximate the lip  412  is now lower, the meter roller  410  cannot engage the agricultural product  420  resting on the floor  409  thereby stopping flow of agricultural product  420  over the lip  412  and stopping flow of agricultural product  420  into the outlet  430 . To prevent agricultural product  420  from slipping between the inclined portion  413  of the meterbox  407  and the floor  409  when the floor  409  is in the lowered position, the floor  409  comprises a matching inclined portion  403  that slides along the inclined portion  413  maintaining a seal between the metering chamber  406  and the exterior of the meterbox. Further, to ensure that the metering chamber  406  doesn&#39;t simply fill up with agricultural product  420  to the level of the meter roller  410  when the floor  409  is in the lowered position, an inlet guard plate  418  depending down from the hopper  450  into the metering chamber  406  is configured to be long enough that the end of the inlet guard plate  418  is at the level of or lower than the lip  412 . To bring the agricultural product  420  back into contact with the meter roller  410 , the trough portion  401  is swung in the reverse direction to raise the floor  409  back to the height depicted in  FIG. 4D  and  FIG. 4E . The trough portion  401  may be raised and lowered by an actuator, for example a linear actuator or a hydraulic cylinder, connecting the trough portion  401  to the hopper  450 . As shown in  FIG. 4D ,  FIG. 4E  and  FIG. 4F , the actuator may be secured to the outside of the hopper  450  at attachment  455  and to the outside of the back wall  402  of the trough portion  401  at attachment  405 . 
     With reference to  FIG. 5A ,  FIG. 5B ,  FIG. 5C ,  FIG. 5D ,  FIG. 5E  and  FIG. 5F , a metering apparatus  500  is shown in which flow of agricultural product  520  from a hopper  550  to an air distribution line (not shown) may be stopped from entering the air distribution line by raising a meter roller  510  away from the agricultural product  520  in a metering chamber  506  to disengage the agricultural product  520  from the meter roller  510 . The metering apparatus  500  comprises the meter roller  510 , in this case a pegged meter roller although any suitable meter roller (e.g. a smooth roller, fluted roller or high output roller) may be employed, mounted on shaft  517  and disposed within the metering chamber  506  of a meterbox  507 . The metering chamber  506  is in communication with the hopper  550  via the inlet  515  so that the agricultural product  520  in the hopper  550  can flow into the metering chamber  506 . The agricultural product  520  collects on a floor  509  of the metering chamber  506  and engages with the meter roller  510 . As seen in  FIG. 5E , when the meter roller  510  is in a lowered position, rotation of the meter roller  510 , in this case clockwise rotation, meters the agricultural product  520  at a regulated rate up and over a lip  512  proximate an end of an inclined portion  513  of the floor  509  of the meterbox  507  to exit the metering chamber  506  through an outlet  530  into the air distribution line, which carries the agricultural product  520  to product application outlets for distribution in a field. 
     When it becomes desirable to cut off flow of the agricultural product  520  to the air distribution line, the meter roller  510  is raised as seen in  FIG. 5A  and  FIG. 5B . The meter roller  510  may be raised by lifting the shaft  517 . Because the meter roller  510  is now higher, the meter roller  510  cannot engage the agricultural product  520  resting on the floor  509  thereby stopping flow of agricultural product  520  over the lip  512  and stopping flow of agricultural product  520  into the outlet  530 . Further, to ensure that the metering chamber  506  doesn&#39;t simply fill up with agricultural product  520  to the level of the meter roller  510  when the meter roller  510  is in the raised position, an inlet guard plate  518  depending down from the hopper  550  into the metering chamber  506  is configured to be long enough that the end of the inlet guard plate  518  is at the level of or lower than the lip  512 . To bring the agricultural product  520  back into contact with the meter roller  510 , the meter roller  510  is lowered back into contact with the agricultural product  520  as depicted in  FIG. 5E . 
     With reference to  FIG. 6A  and  FIG. 6B , two side-by-side metering apparatuses  600   a ,  600   b  are depicted each operating similarly to the metering apparatus depicted in  FIG. 5A  to  FIG. 5F . Both metering apparatuses  600   a ,  600   b  are housed in the same meterbox  607 . The metering apparatus  600   a  comprises a roller housing that is shown housing meter roller  610   a  in a raised, product disengaging position, while the metering apparatus  600   b  comprises a roller housing that is shown housing meter roller  610   b  in a lowered product engaging position. The housing that houses meter roller  610   a  is raised and lowered by actuator  674   a , while the housing that houses meter roller  610   b  is raised and lowered by actuator  674   b . The actuators  674   a  and  674   b  may be independently controlled so that one or the other or both meter rollers  610   a ,  610   b  may be metering or not metering agricultural product. 
     The meter rollers  610   a ,  610   b  are constantly driven by the same drive axle  627 , whether in the raised or lowered positions. The meter rollers  610   a ,  610   b  are mounted on separate shafts (not shown) together with separate gears. Gear  615   a  for meter roller  610   a  can be seen in  FIG. 6A . The gears are intermeshed with sprockets  628   a ,  628   b  mounted on and driven by the drive axle  627 . The drive axle  627  drives the sprockets  628   a ,  628   b , which in turn drive the gears and thus the meter rollers  610   a ,  610   b . The drive axle  627  also provides an axis for the meter rollers  610   a ,  610   b  to pivot about when being raised and lowered by the actuators  674   a  and  674   b . Raising and lowering the meter rollers  610   a ,  610   b  does not disengage the gears from the sprockets so the meter rollers  610   a ,  610   b  are always driven, whether or not they are actively metering agricultural product. Because the meter rollers  610   a ,  610   b  are mounted on separate shafts, servicing the meter rollers  610   a ,  610   b , for example, cleaning or changing out the meter rollers, is facilitated as the meter rollers  610   a ,  610   b  may be accessed, and if needed individually removed, through access ports  621   a ,  621   b . The structure and operation of the remainder of the metering apparatuses  600   a ,  600   b  are like that described in connection with  FIG. 5A  to  FIG. 5F . 
     The metering apparatuses  600   a ,  600   b  are shown in cooperation with air distribution lines  640   a ,  640   b  therebelow. The air distribution lines  640   a ,  640   b  are housed in an air distribution box  645  and each line  640   a ,  640   b  receives agricultural product metered by the metering apparatus directly thereabove. Agricultural product metered into each line  640   a ,  640   b  is carried by a flow of air to product application outlets for distribution in a field. 
     With reference to  FIG. 7A ,  FIG. 7B  and  FIG. 7C , a metering apparatus  700  is shown in which flow of agricultural product from a hopper  750  to an air distribution line  751  may be stopped from entering the air distribution line  751  by moving, in this case lowering, the agricultural product in a metering chamber  706  away from a continuously turning meter roller  710  to disengage the agricultural product from the meter roller  710 . The metering apparatus  700  comprises the meter roller  710 , in this case a pegged meter roller although any suitable meter roller (e.g. a smooth roller, fluted roller or high output roller) may be employed, mounted on shaft  717  and disposed within the metering chamber  706  of a meterbox  707 . The metering chamber  706  is in communication with the hopper  750  via a tube  714  having an inlet  715  so that the agricultural product in the hopper  750  can flow through the tube  714  into the metering chamber  706 . The agricultural product collects on a floor  709  of the metering chamber  706  and engages with the meter roller  710 . As seen in  FIG. 7B , when the floor  709  of the metering chamber  706  is in a raised position, rotation of the meter roller  710 , in this case counterclockwise rotation, meters the agricultural product at a regulated rate up and over a lip  712  proximate an end of an inclined portion  713  extending up from the floor  709  to exit the metering chamber  706  through an outlet  730  into the air distribution line  751 , which carries the agricultural product to product application outlets for distribution in a field. 
     When it becomes desirable to cut off flow of the agricultural product to the air distribution line  751 , the floor  709  of the metering chamber  706  is lowered as seen in  FIG. 7A  and  FIG. 7C . The meterbox  707  comprises a trough portion  701 , the trough portion  701  comprising the floor  709 , a back wall  702  and a ceiling portion  703 , the ceiling portion  703  secured to the tube  714  so that agricultural product may flow from the tube  714  into the metering chamber  706  through an aperture in the ceiling portion  703 . To lower the floor  709 , the trough portion  701  and the tube  714  to which the ceiling portion  703  of the trough portion  701  is secured, are linked to an actuator  727  (e.g. a hydraulic cylinder or an electric actuator) through a flange  728  secured to the back wall  702  of the trough portion  701 . The flange  728  is linked to a plunger  729  by a linkage pin  730 , and the plunger  729  is connected to an extendible rod  726  of the actuator  727 . Extension of the rod  726  pushes the trough portion  701  and the tube  714  vertically downward to the lowered product disengaging position as seen in  FIG. 7A  and  FIG. 7C , while retraction of the rod  726  pulls the trough portion  701  and the tube  714  vertically upward to the raised product engaging position as seen in  FIG. 7B . A compression spring  731  seated around the plunger  729  is compressed when the rod  726  is extended thereby exerting a bias on the trough portion  701  and the tube  714  back toward the raised position. In case of a failure of the actuator  727 , the spring  731  ensures that the trough portion  701  and the tube  714  are in the raised position so that metering of agricultural product into the air distribution line  751  may continue. While the tube  714  is depicted as cylindrical, any suitable cross-sectional shape of tube may be employed, for example an elliptical or a polyhedral cross-section (e.g. triangular, square, rectangular, pentagonal, hexagonal and the like). A polyhedral cross-section provides a benefit of reducing a tendency of the tube to twist or move laterally while being raised and lowered. To further reduce the tendency of the tube  714  to move laterally while being raised and lowered, the tube  714  is bracketed by guides  734  and  735 , the tube  714  being allowed to move vertically freely within the guides  734  and  735 . 
     The novel features of the present invention will become apparent to those of skill in the art upon examination of the detailed description of the invention. It should be understood, however, that the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the specification as a whole.