Abstract:
An air velocity indicator and control device is provided for use with pneumatic distribution systems used in air seeders that pneumatically discharge agricultural product to the ground, seedbed, or furrow. The air velocity indicator and control device includes a tubular housing, extending between an inlet and an outlet, and pivotally housing a deflectable plate that actuates in response to encountering an airflow entrained with agricultural product. A magnitude of deflection of the deflectable plate, corresponding to airflow velocity, can be displayed through an indicator assembly. This enables a user to identify velocity variances and differentials within the air seeder and make corrective adjustments. In some implementations, multiple air velocity indicator and control devices are ganged together with deflectable plates that pivot in unison with each other. The relative angle of fixation of the deflectable plates, upon the pivot pin, can be adjusted to permit airflow tuning as needed.

Description:
FIELD OF THE INVENTION 
   The invention relates generally to pneumatic particulate matter distribution systems for agricultural applications, and in particular, to a device and corresponding method for monitoring and regulating airflow rate differentials between multiple air lines in such pneumatic particulate matter distribution systems. 
   BACKGROUND OF THE INVENTION 
   Modern pneumatic particulate distribution systems, commonly referred to as air seeders, are used to distribute seed, fertilizer, or other particulate matter during various agricultural practices. Air seeders typically include an air cart and a tilling implement which are towed in tandem behind a tractor. 
   The air cart includes a frame riding upon wheels and tires, and one or more frame-mounted product tanks for holding granular product, such as seed, fertilizer, herbicide and/or other product. The product tanks are each connected to a product metering device which feeds the product into a pneumatic distribution system in a controlled manner. Typically various components within the product metering device(s) and/or pneumatic distribution system(s) are controlled by any of a variety of suitable electronic controls. 
   In general, the pneumatic distribution system functions to intake granular product from the metering device, transport it to the tilling implement, and then deliver the product to the field. In particular, the pneumatic distribution system includes a primary distribution manifold that intakes the product from the metering device and also an airflow from a centrifugal fan. The rotational speed of the centrifugal fan can be controlled by such electronic controls, as desired. 
   Controlling the rotational speed of the centrifugal fan influences a resultant airflow velocity within the pneumatic distribution system. Furthermore, the airflow velocity within the pneumatic distribution system can be influenced by, e.g., articulating baffles placed with the system that can be “opened” to provide relatively less system flow resistance or “closed” to provide relatively more system flow resistance. Typically, such baffles are placed upstream in the pneumatic distribution system; in other words, between the centrifugal fan and the primary distribution manifold. 
   The primary distribution manifold intakes an airflow delivered by the centrifugal fan and product delivered by the metering device into a common chamber, whereby the product is introduced into and becomes entrained in the airflow. The primary distribution manifold divides the airflow(s) and directs the airflow and the entrained product through multiple air cart air lines. The air cart air lines attach to a series of secondary distribution manifolds, commonly referred to as “headers,” typically at the tilling implement. The headers further distribute the airflow and entrained product through multiple implement distribution air lines, to multiple ground openers on the tilling implement. At this point, the air bleeds off through an air vent, whereby the product falls by way of gravity to the ground or seedbed. Optionally, the product falls by way of gravity into a planting unit for singulation prior to seedbed or furrow delivery. 
   The use of precision-type agricultural practices is becoming increasingly popular, as is the desire to improve the operating efficiency of agricultural equipment. In light of precision-type agricultural practices and desire to improve efficiency, known air seeders exhibit certain limitations. For example, at times during use, various components of the pneumatic distribution system can encounter flow resistances and corresponding operating pressures and flow velocities that are outside of a desired or optimal range. Such non-desired operating parameters can be effectuated at least in part by, e.g., (i) the distance that the airflow and entrained product travels within the pneumatic distribution system, (ii) the numerous mechanical interfaces that the airflow and entrained product encounters during system travel, e.g., couplers, baffles, or other structures within manifolds, arcuate lengths of air line sidewalls, (iii) wear and maintenance status of components within the pneumatic distribution system, and (iv) various other factors and conditions. 
   Such occurrences of non-desired operating air line resistances, pressures, and flow velocities typically include non-equal magnitudes of airflow velocity, or airflow velocity differentials, between the various air lines within the air distribution system. As a result, the integrity and consistency of the seeding volume as a function of time and/or seed distribution pattern upon the ground, field, seedbed, or furrow can be compromised. Correspondingly, overseeding, underseeding, or inconsistent seeding distribution patterns can result. 
   Airflow velocity differentials typically result from at least one air line having a relatively lower airflow resistance value, and correspondingly a relatively higher or excessive airflow velocity value, as compared to the other air lines within the pneumatic distribution system. This excessive airflow velocity requires higher static air line pressure(s) to transmit, which in turn requires more power input to achieve, potentially wasting energy in the process. Furthermore, the excessive airflow velocity causes excessive abrasive wear to the inner surfaces of the air line. Namely, the airflow entrained product collides with such inner surfaces at a corresponding greater velocity, thus with more force and greater frequency, thereby causing more abrasive damage. Conversely, a minimum airflow velocity must be maintained to suitably entrain and transport the product through the air seeder, whereby airflow velocities falling below the minimum can result in plugging, clogging, or accumulation of product within the pneumatic delivery system. 
   Previous attempts have been made to equalize the pressures and airflow velocities between various air lines in seeders, to decrease the magnitude of the airflow velocity differential. For example, devices and corresponding methods have been previously provided for monitoring particle velocity of the airflow entrained product and controlling a flow restricting damper or the rotational velocity of the centrifugal fan in accordance therewith, to mitigate the airflow velocity differential. While such systems have been adequate, they require sophisticated electronics and controls, and are relatively expensive to produce and maintain. 
   SUMMARY OF THE INVENTION 
   There is a need for an air seeder that provides monitoring and regulation of airflow velocities within a pneumatic distribution system, to mitigate airflow velocities differentials between individual air lines. There is also a need for an air seeder that reduces the number of parts and electronic complexity of pneumatic distribution system monitoring devices. Furthermore, there is a need for air seeders with pneumatic distribution systems that can be regulated and adjusted manually and/or automatically on a per individual air line basis, whereby inconsistent seed coverage, underplanting, overplanting, and energy wasting can be managed and minimized. 
   The present invention provides an airflow velocity indicator and control mechanism or device which meets the desires and needs described above, while being used, e.g., in combination with an air seeder. In a first embodiment of the present invention, the air velocity indicator and control device includes an inlet and an outlet, with a tubular housing extending therebetween. A deflectable plate is provided in the housing and configured to actuate in response to encountering the airflow entrained with agricultural product. A magnitude of deflection of the deflectable plate is displayed through an indicator assembly, such that the indicator assembly shows a value for the airflow velocity through the device. This enables a user to identify velocity variances and differentials between various components of the air seeder and make corrective adjustments as desired. 
   It is contemplated for the deflectable plate to be mounted generally transversely in the tubular housing void space, and the deflectable plate to have a different perimeter shape than that of the inlet. In this configuration, the tubular housing can also have a different perimeter shape, and/or optionally the cross-sectional area, as compared to the inlet or the outlet, as desired. 
   In still further implementations, the deflectable plate actuates by pivotal movement within the tubular housing. This can be done by way of a pivot pin, attached to an upper edge of the deflectable plate that is mounted transversely through an upper portion of the tubular housing void space. 
   Other objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout. 
       FIG. 1  illustrates an isometric view of a first embodiment of an airflow velocity indicator and control device in accordance with the present invention. 
       FIG. 2  illustrates a side elevational view of the airflow velocity indicator and control device shown in  FIG. 1 . 
       FIG. 3  illustrates an isometric view of a portion of the airflow velocity indicator and control device shown in  FIG. 1 , with portions of the sidewalls of the tubular deflector housing removed. 
       FIG. 4  illustrates an isometric view of multiple airflow velocity indicator and control devices, ganged together, in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a preferred embodiment of an air velocity indicator and control device  10  employed on a pneumatic distribution system  5  of an air seeder (not shown). Although no specific air seeder is illustrated, it is well understood that air velocity indicator and control device  10  can be incorporated into any of a variety of suitable air seeders and air seeder components, e.g. air carts and tillage implements, such as various ones manufactured by CNH America LLC. Suitable air carts include Case IH models ADX2230, ADX3380, ADX3430 air carts, and others. Suitable tillage implements include Case IH models ATX400 and ATX700 air hoe drills. 
   Notwithstanding, air velocity indicator and control device  10  can be used with yet other known and available air seeders. Known, readily available, air seeders typically include an air cart and a tilling implement, towed in tandem behind a tractor, for pneumatically distributing seed or other particulates or granular product such as fertilizer, herbicide, or other product. The air cart includes one or more frame-mounted product tanks for holding the granular product and each of the product tanks is connected to a product metering device which feeds the product into a pneumatic distribution system  5  in a controlled manner. Typically various components within the product metering devices and/or pneumatic distribution systems  5  are controlled, at least in part, by any of a variety of suitable electronic controls, e.g., an air seeder electronic control system. 
   Conventional pneumatic distribution systems  5  intake granular product from the metering device, and by way of a primary distribution manifold  6 , mix, suspend, or entrain the product into an airflow that is produced and delivered by a centrifugal blower or fan. Controlling the rotational speed of the centrifugal fan, as well as mechanically controlling the orifice size through which the centrifugal fan delivers its airflow, influences a resultant airflow velocity within the pneumatic distribution system. 
   Typical air seeder pneumatic distribution systems  5  include multiple air cart air lines  7 , connected to and extending between the primary distribution manifold(s)  6  and a series of secondary distribution manifolds, commonly referred to as “headers,” illustrated as headers  8 . The headers  8  further divide and distribute the airflow and entrained product through multiple tilling implement distribution air lines, to multiple ground openers or planting units for seed singulation on the tilling implement. 
   Referring now to  FIGS. 1-3 , air velocity indicator and control device  10  can be incorporated anywhere within the pneumatic distribution system  5  of an air seeder. However, it is preferable mounted downstream of a primary distribution manifold. For implementations of air velocity indicator and control device  10  that are retrofitted to existing air seeders, the device  10  is mounted with the pneumatic distribution system  5  at a location which is easily accessible, requires relatively little disassembly of the air seeder components, assemblies, or subassemblies, and thus facilitates simple installation. Such locations are where the existing air seeder has accessible mechanical linkages or couplers joining the various components of the pneumatic distribution system  5 , e.g., between the (i) primary distribution manifold  6  and air cart air lines  7 , (ii) air cart air lines  7  and headers  8 , (iii) headers  8  and tilling implement distribution air lines, (iv) tilling implement distribution air lines and seed tubes or planting units, and/or (v) elsewhere as desired. 
   Air velocity indicator and control device  10  includes a body  20  and indicator assembly  100  that is mounted at least partially with the body  20 . Body  20  is an assemblage of an inlet  25 , an inlet transition segment  30 , a tubular deflector housing  35 , an outlet transition segment  40 , and an outlet  45 . 
   Inlet  25  is an elongate hollow member that provides an incoming conduit for the air velocity indicator and control device  10 . The particular size, shape, and configuration of inlet  25  corresponds to the component it interfaces with, whereby inlet  25  is configured based at least in part on where in the pneumatic distribution system  5  it is located. Accordingly, for the implementations mounted between air cart air lines  7  and headers  8 , such as those seen in  FIGS. 1-3 , the inlet  25  is round in cross-section and sized and configured to suitably couple to, e.g., a 2.5 inch or other air cart air line by a conventional mechanical coupler. 
   The end of inlet  25  that is proximate the remainder of air velocity indicator and control device  10  connects to an inlet transition segment  30 . Inlet transition segment  30  has a first end  31  that is joined to inlet  25  and correspondingly approximates the dimensional attributes of the end of inlet  25 . Multiple sidewalls  32 , optionally a single circumferential sidewall  32 , extend longitudinally from the first end  31 . In some implementations, the sidewalls laterally diverge from the first end  31 , defining an outwardly flared configuration. 
   In any event, the sidewalls  32  are joined to each other at respective lateral edges, whereby they, in combination, suitably covert the configuration of inlet  25  and first end  31  to join with the tubular deflector housing  35 , by way of second end  33 . Second end  33  is defined at the portion of inlet transition segment  30  which is distal inlet  25 . Accordingly, the second end  33  interfaces with first end  36  of tubular deflector housing  35 . 
   First end  36  of tubular deflector housing  35 , in some implementations, appears square or rectangular as viewed in a front elevation. The particular perimeter shape of first end  36  of tubular deflector housing  35  is selected to correspond to the cross-sectional configuration of the medial portion of tubular deflector housing  35 , characterized by a perimeter of combination of multiple sidewalls  37 . 
   The cross-sectional configuration of tubular deflector housing  35 , defined by the multiple sidewalls  37 , can be any of a variety of arcuate or polygonal configurations, as desired. It is noted, however, that the perimeter defined about the outer surfaces of sidewalls  37 , and thus the cross-sectional configuration of deflector house  35  corresponds to the particular configurations of various components of indicator assembly  100 , explained in greater detail hereinafter. The sidewalls  37  terminate at their intersection with a second end  38  of tubular deflector housing  35 . The second end  38  provides the interface between the tubular deflector housing  35  and the second transition segment  40 , namely, the first end  41  of outlet transition segment  40 . 
   Still referring to  FIGS. 1-3 , in implementations of tubular deflector housing  35  that have a generally constant cross-sectional configuration along its length, the first end  41  of the outlet transition segment  40  corresponds in size, shape, and configuration to the second end  33  of the inlet transition segment  30 . In other words, when the ends  36 ,  38  of tubular deflector housing  35  are analogous, so too are the ends of the inlet and outlet transition segments  30 ,  40 , namely, second end  33  and first end  41 , respectively. 
   Multiple sidewalls  42 , optionally a single circumferential sidewall  42 , extend longitudinally from the first end  41 . In some implementations, the sidewalls  42  laterally converge toward each other from the first end  41 , defining an inwardly tapered configuration. Sidewalls  42  are joined to each other at respective lateral edges, whereby they, in combination, serve as the joining mechanism that connects the tubular deflector housing  35  with the outlet  45 . Stated another way, second end  43  is defined at the portion of outlet transition segment  40  which is distal the tubular deflector housing  35 , and attaches to outlet  45 . 
   Outlet  45  is an elongate hollow member that provides an outgoing conduit for the air velocity indicator and control device  10 . Like inlet  25 , the particular size, shape, and configuration of inlet  45  corresponds to the particular component it interfaces with, within the pneumatic distribution system  5 . For example, in implementations having the air velocity indicator and control device  10  mounted between air cart air lines  7  and headers  8 , such as those seen in  FIGS. 1-3 , the outlet  45  is round in cross-section and sized and configured to suitably couple to a 2.5 inch or other header by a conventional mechanical coupler. 
   The airflow velocity and thus the velocity of the entrained product within the pneumatic distribution system  5 , e.g., between the air cart air line  7  and header  8  as seen in  FIGS. 1-3 , is determined by way of an indicator assembly  100 . Indictor assembly  100  includes a deflection plate assembly  110 A and a gauge assembly  125 . 
   Deflection plate assembly  110 A includes a deflectable plate  111  pivotably housed between the inwardly facing surfaces of tubular deflector housing sidewalls  37 , namely, within a void space  39 . Referring now to  FIG. 3 , deflectable plate  111  is a planar, damper-type structure that defines a width dimension between opposing lateral edges  112 ,  113 . This width dimension corresponds closely to the width dimension of the tubular deflector housing  35  void space, and thus, in some implementations, occupies a substantial portion of void space  39  with relatively small clearances between the lateral edges  112 ,  113  and the respective tubular deflector housing sidewalls  37 . 
   Referring to  FIG. 3 , deflectable plate  111  defines a length dimension between an upper edge  114  and a lower edge  115 . In a resting state, the lower edge  115  can sit upon, e.g., an upwardly facing surface of the lowermost sidewall  34 . Preferably the length dimension of the deflectable plate  111  is greater in magnitude than the height dimension of the void space  39 . In this configuration, the deflection extends angularly between an opposing pair of sidewalls  37  on opposite sides of the void space  39 . In some implementations, the deflectable plate  111  extends angularly and downwardly from the uppermost sidewall  37  to the lowermost sidewall. 
   Upper edge  114  is attached to a pivot pin  116  that extends parallel to, but is spaced downwardly from, the uppermost sidewall  37 . Pivot pin  116  defines an axis of pivotation about which the deflectable plate  111  articulates while the air seeder is being used. In some implementations, the deflectable plate  111  and pivot pin  116  are fixedly attached to each other, whereby they pivot or rotate in unison. Such configuration permits the pivot pin  116  to serve as the interface between the deflection plate assembly  110 A and gauge assembly  125 . 
   Gauge assembly  125  includes indicator arm  128 , indicator scale  130 , and can further include wiper arm  135 , resistor  140 , and conductors  145 , as desired. Indicator arm  128  is fixedly mounted to an end of pivot pin  116 , whereby it pivots or rotates in unison with both the pivot pin  116  and the deflectable plate  111 . In other words, indicator arm  128  is a needle-type member that extends radially from the pivot pin  116 . It is configured to be visually conspicuous against a scale indicating, e.g., airflow velocity, such as indicator scale  130 . Accordingly, in combination, indicator arm  128  and indicator scale  130  provide a visual representation of the airflow velocity through air velocity indicator and control device  10  and thus through a respective segment of pneumatic distribution system  5 . 
   As desired and/or as required for suitable operation and functionality, the gauge assembly  125  can further include a spring or other resilient member (not illustrated) to biasingly urge the deflectable plate  111 , pivot pin  116 , and indicator arm  128  toward their resting state positions. For example, a spring or other resilient member can be required when the mass of deflectable plate  111  is small enough, and the airflow velocity is great enough, that the indicator arm  128  is held against the indicia indicating a maximum value on the indicator scale  130 . 
   In some implementations, it is desired to electronically monitor or determine the airflow velocities within the airflow velocity indicator assembly  100 . In such implementations, various other components are provided to suitably sense or determine the position of deflectable plate  111 , pivot pin  116 , indicator arm  128 , and/or other components of airflow velocity indicator assembly  100 . This enables such mechanical positional information to be sensed, detected, or determined, and to also be conveyed to the air seeder electronic control system or other suitable controller or electronic control module. 
   In such implementations, the gauge assembly  125  can further include, e.g., wiper arm  135 , resistor  140 , and conductors  145 . The wiper arm  135  is mounted to pivot pin  116  or attached directly to indicator arm  128 , but in any event moves in unison with the indicator arm  128 . Resistor  140  is attached to and extends along the length of the backside of indicator scale  130 . While moving, wiper arm  135  is always in mechanical contact with the resistor such that the particular location of wiper arm  135  along the length of resistor  140  varies according to the position of indicator arm  128  and indicator scale  130 . 
   When the wiper arm  135  and resistor  140  are energized, the resultant output voltage output across them changes, based on where the wiper arm  135  contacts the resistor  140  along its length. In other words, the wiper arm  135  and resistor  140  are configured as, e.g., a potentiometer or rheostat to provide a variable output voltage signal which the air seeder electronic control system interprets to determine the position of wiper arm  135  along resistor  140 , indicator arm  128  along indicator scale  130 , deflectable plate  111  within void space  39 , and thus the velocity of the airflow flowing through air velocity indicator and control device  10 . 
   Regardless of the particular monitoring methods, manually or electronically monitored or observed, the airflow entrained with product provides a force which deflects respective ones of the deflectable plates  111  and indicator arms  128 . Correspondingly, the differential velocities will cause resulting deflection variances that are observable or can be monitored. Based on this information, in other words the variance or differential information, the airflow can be controlled manually or automatically to reduce the magnitude of the velocity differentials. 
   Referring now to  FIG. 4 , as desired, multiple air velocity indicator and control devices  10  or components thereof can be joined, ganged, banked, or otherwise linked together. Such configuration can be useful when the air velocity indicator and control devices  10  are mounted in relatively space-constricted areas, for example, at locations within pneumatic distribution system  5  where multiple air lines, such as air cart air lines  7 , are in close proximity to each other, and/or for automatic regulation. Accordingly, multiple joined air velocity indicator and control devices  10  are well-suited for placement between primary distribution manifold  6  and air lines  7 , or elsewhere as desired. 
   Regardless of the particular placement location within pneumatic distribution system  5 , some implementations of joined air velocity indicator and control devices  10  are adapted and configured to automatically and passively self-regulate the volumes and velocities of airflow passing therethrough. This can be done by introducing analogous mechanical airflow restrictions, by way of deflectable plates  111  positioned at the same angle(s) of deflection, into airflows having differing velocities. Since the airflows have different velocities, analogous mechanical airflow restrictions correspondingly produce differing effects on such differing airflows. Air velocity indicator and control devices  10  exploit such tendencies of the analogously positioned deflectable plates  111  to produce differing effects in differing airflows to redirect or shunt portions of relatively high velocity airflows into relatively low velocity airflows. This is typically done by modifying the relative flow resistances defined through different bodies  20 , which shunt or redirect portions of the upstream airflow through respective branches of pneumatic distribution system  5 , whereby the lines  7  correspondingly define airflows that have relatively more similar velocities. 
   Still referring to  FIG. 4 , in some implementations, the air velocity indicator and control device  10  has multiple bodies  20  and a ganged deflection plate assembly  110 B. Namely, the ganged deflection plate assembly  110 B has a single, common pivot pin  116  which extends through all of the parallel adjacent bodies  20  effectively ganging all of the deflectable plates  111  together. In this configuration, all of the deflectable plates  111  are fixed to a common pivot pin  116 , whereby the deflectable plates  111  must pivot or rotate in unison with each other. Thus, at a given point in time, the pivotal or rotational position of the deflectable plates  111  is a function of all forces applied to the ganged deflectable plate assembly  110 B. Correspondingly, the position of a deflectable plate within its respective body  20  is determined not only by operating conditions and characteristics within any single body  20 , but is also influenced by the operating conditions and characteristics within all other bodies  20 . In other words, since the deflectable plates  111  pivot or rotate in unison with each other, pivoting a single deflectable plate  111  correspondingly changes the relative opening dimensions within all bodies  20  simultaneously. In this regard, pivoting, rotating, or otherwise actuating the ganged deflectable plate assembly  1110 B dynamically changes the opening dimensions and air flow characteristics of all bodies  20  simultaneously. 
   Although the deflectable plates  111  pivot or rotate in unison with each other, they need not be provided at the same, or constant, relative angular orientations upon the pivot pin  116 . Preferably, each of the deflectable plates  111  is independently and adjustably fixed or mounted to the pivot pin  116 , by way of e.g., setscrew(s), grub screw(s), locking collar(s), and/or other suitable temporary fixation hardware or devices. As desired, the deflectable plates  111  can be in coplanar alignment with each other, while enabling the user to later adjust each of the deflectable plates  111  to intersect with the pivot pin  116  at a different angle(s) with respect to the outer circumferential surface of the pivot pin  116 . This permits the user to adjust the default or resting state opening dimensions of the bodies  20 , enabling airflow characteristic tuning to enhance the self-regulatory functionality of air velocity indicator and control device  10 . 
   Since the entire volume of air flowing through the air velocity indicator and control device  10  originates from a single centrifugal fan, blower, or other source, airflow pressures, velocities, and volumes in each of the bodies  20  and air lines  7  are intimately related to those within all other bodies  20  and air lines  7 . Differences in the values of pressures, volumes, and velocities between individual air lines  7  typically correspond to differences in airflow resistance values of the air lines  7 . Generally, air lines  7  with low resistances have relatively high airflow velocities and air lines  7  with high resistances have relatively low airflow velocities, whereby pneumatic distribution systems  5  having differing airflow resistance values through different parallel components define airflow velocity differentials. 
   Still referring to  FIG. 4 , ganged deflectable plate assembly  110 B mitigates the magnitudes of velocity differentials by applying an inversely resistive relationship to the low and high resistance air lines  7  moving the values of the differing airflow velocities toward a common value. Namely, within the air velocity indicator and control device  10 , ganged deflectable plate assembly  110 B introduces a relatively low resistance to the high resistance (low velocity) air lines  7  and a relatively high resistance to the low resistance (high velocity) air lines  7 . In this regard, the ganged deflectable plate assembly  110 B inversely influences or offsets the relative velocity status of the air lines  7 , whereby the low velocity air lines  7  perceive a relatively small resistance and the high velocity air lines  7  perceive a relatively large resistance to mitigate the velocity differential. 
   Airflows passing through the high velocity lines thus lose energy and relative velocity by urging the ganged deflectable plate assembly  1110 B further open. The low velocity lines  7  realize an opposite effect since the other, high velocity airflows increase the sizes of the opening within the bodies  20 . Namely, airflows passing through the low velocity lines  7  increase their relative velocities by (i) losing velocity to a lesser rate or extent as compared to those flowing through the high velocity lines  7 , or (ii) gaining actual velocity, since the high velocity airflows relieve some of the resistive burden from the low velocity lines  7  by urging the ganged deflectable plate assembly  110 B further open. In this regard, the air velocity indicator and control device  10  influences each of the distinct airflows passing therethrough, whereby the resultant airflow velocities are closer to each other in magnitude, as compared to when the air velocity indicator and control device  10  is not utilized. In this manner, deviations from a velocity equilibrium of each of the airflows are attenuated or otherwise reduced, and, accordingly, so is the velocity differential. 
   Still referring to  FIG. 4 , it is apparent that during use, suitably consistent airflow velocities between the various airlines  7  are achieved by the automatic, passive, and mechanical self-regulation which is influenced, at least in part, by (i) the fluid dynamic characteristics of the individual airflows traversing the individual bodies  20 , (ii) the relationships between the individual airflows traversing the individual bodies  20 , (iii) the airflow induced mechanical reactive tendencies of the deflectable plates  111  within its respective body  20 , and (iv) the cumulative effect(s) of such mechanical reactive tendencies of the deflectable plates  111  upon each of the airflows through the respective bodies  20  and the overall position of the ganged deflection plate assembly  110 B. 
   Referring again to  FIGS. 1-4 , it is apparent that the air velocity indicator and control device  10  provides a simple, cost effective, primarily mechanical device and method for determining airflow velocity in various portions of a pneumatic distribution system  5  of an air seeder. This is because the air velocity indicator and control devices  10  can be easily mounted into existing joints or coupling sites of pneumatic distribution system  5 , where mechanical fasteners or couplers are typically located. Furthermore, the air velocity indicator and control device  10  is devoid of sophisticated electronics and function primarily by way of simple, inexpensive, and reliable mechanical components. In other words, air velocity indicator and control device  10  enables monitoring and control of airflow velocities without having to determine particle velocity, which typically requires sensitive and sophisticated sensors and corresponding devices. 
   In light of the above, during use, the air velocity indicator and control devices  10  are either installed by the user at existing joints or points of intersection of the pneumatic distribution system  5  components, or are previously installed by the air seeder manufacturer. Providing an air velocity indicator and control devices  10  at each of the relevant pneumatic distribution system  5  components, such as at each air cart air line and/or header  8 , the user can easily determine the relative velocities between the various air cart air lines  7  or headers  8 . Based on this information, the user can manually reduce the velocity differential between respective ones of the various air cart air lines  7  or headers  8 . 
   For example, the user can observe the position of each of the indicator arms  128  upon indicator scale  130 , thereby using indicator assembly  100  to quantify or evaluate the airflow velocity in each of the air cart air lines  7  or headers  8 . If one or more of the velocities is greater than the desired velocity, which might correspond, e.g., to the lowest observed velocity, the user can perform the needed upstream or downstream adjustments to effectuate the desired change in airflow velocity to manually reduce the velocity differential. In other words, the user can adjust the rotational speed of the centrifugal fan at the air cart, or actuate various baffles to widen or restrict various openings, or utilize other suitable known louvers or adjustable internal airflow resistors, within the relevant portion of the pneumatic distribution system  5 , until the desired airflow velocity is achieved and the velocity differential attains an acceptably low value. 
   Referring again to  FIG. 4 , ganging the deflectable plates  111  to provide ganged deflectable plate assembly  110 B enables the air velocity indicator and control device  10  to automatically and passively self-regulate the airflow velocities so that the velocity differentials are suitably small so that the air seeder operates acceptably without requiring a substantial capital investment from the user. In some implementations, the air velocity indicator and control device  10  obviates the need for indicator assembly  100  ( FIGS. 1-3 ) or electronic sensors, feedback mechanisms, and/or controls, as desired. This regulation of airflow velocities in air lines  7  of seeders at a substantially lower cost as compared to sophisticated electronically controlled devices and systems. 
   While the invention has been shown and described with respect to particular embodiments, it is understood that alternatives and modifications are possible and are contemplated as being within the scope of the present invention. A wide variety of air seeders (e.g., conventional air seeders and respective air carts and tilling implements) can employ the air velocity indicator and control devices  10  of the present invention. In addition, it should be understood that the number of air velocity indicator and control devices  10  on the air seeder is not limiting on the invention. 
   Many changes and modifications could be made to the invention without departing from the spirit thereof. The scope of these changes will become apparent from the appended claims.