Pressure balanced meter assembly and method of use

A meter assembly for an agricultural machine includes a meter, a conduit, and a bypass. The meter includes a roller to move commodity to the conduit. The bypass is coupled to the conduit and the meter to facilitate air flow therebetween free of interference from the roller or the commodity.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to optimizing air flow in an air seeder and more specifically to balancing pressure in an air seeder having a meter assembly.

BACKGROUND

Modern air seeders utilize airflow through conduits to direct commodity such as fertilizer and seed to a desired location. Typically, the commodity is stored in a tank on a cart and selectively provided to conduits to be further transported to a drill assembly or otherwise ultimately placed in the underlying soil. A meter is often positioned between the tank and the conduit to selectively distribute commodity from the tank into the conduit. There is a need for optimizing air flow in the meter assembly and balancing pressure on opposite sides of the meter.

SUMMARY

In an illustrative embodiment of the present disclosure, a meter assembly for an agricultural machine comprises: a meter having an inlet, an outlet, and a roller including cavities configured to receive commodity from the inlet and release commodity to the outlet; a first conduit fluidly coupled to the outlet of the meter and configured to receive commodity therefrom; a commodity path including the inlet, the outlet, and the cavities of the roller; and a bypass assembly including at least one passageway fluidly coupled to the meter and the conduit; the at least one passageway includes a first end fluidly coupled to the meter at one or more locations above the roller and a second end fluidly coupled to the first conduit. In some embodiments, the at least one passageway of the bypass assembly is not inclusive of any portion the commodity path.

In some embodiments, the meter assembly further comprises: a housing in which the roller is positioned, and a commodity tank coupled to the housing and configured to release commodity to the roller; the bypass assembly is positioned in the housing. In some embodiments, the housing includes an inner wall assembly and an outer wall assembly; the roller is positioned inside the inner wall assembly; and the bypass assembly is positioned outside the inner wall assembly and between the inner wall assembly and the outer wall assembly.

In some embodiments, the at least one passageway includes: a first passageway fluidly coupled at a first end to the meter at a location above the roller and at a second end to the first conduit, and a second passageway fluidly coupled at a first end to the meter at a location above the roller and at a second end to a second conduit that is fluidly coupled to the outlet of the meter and configured to receive commodity therefrom. In some embodiments, the first ends of the first and second passageways are a single duct terminating in a single aperture located above roller; and the second ends of first and second passageways are separate ducts that merge at a y-shaped split positioned between the first ends and the second ends. In some embodiments, the first and second passageways are discrete passageways.

In some embodiments, the meter assembly further comprises: a second conduit that is fluidly coupled to the outlet of the meter and configured to receive commodity therefrom; and the at least one passageway includes: (i) a first passageway fluidly coupled to the meter above the roller and to the first conduit, and (ii) a second passageway fluidly coupled to the meter above the roller and to the second conduit; and the first and second passageways are not inclusive of any portion the commodity path.

In some embodiments, the meter assembly further comprises: a first valve positioned in the first passageway and configured move from an open position to a closed position to prevent airflow between the first conduit and the meter via the first passageway; and a second valve positioned in the second passageway and configured move from an open position to a closed position to prevent airflow between the second conduit and the meter via the second passageway.

In some embodiments, the meter assembly further comprises: a housing including an inner wall assembly and an outer wall assembly; the bypass assembly is positioned between the inner wall assembly and the outer wall assembly of the housing. In some embodiments, the inner wall assembly includes a first section and a second section spaced apart from the first section; the outer wall assembly includes a first portion adjacent the first section of the inner wall assembly and a second portion adjacent the second section of the inner wall assembly; and the roller is positioned between the first section of the inner wall assembly and the second section of the inner wall assembly.

In some embodiments, the first passageway is defined between the first section of the inner wall assembly and the first portion of the outer wall assembly; and the second passageway is defined between the second section of the inner wall assembly and the second portion of the outer wall assembly. In some embodiments, the first section of the inner wall assembly the includes an upper aperture fluidly coupling the first passageway to the meter at a first location above roller; and the second section of the inner wall assembly includes an upper aperture fluidly coupling the second passageway to the meter at a second location above roller.

In some embodiments, the first end of the bypass assembly includes at least one aperture fluidly coupling the first and second passageways to the meter at one or more locations above the roller; and the second end of the bypass assembly includes a first aperture fluidly coupling the first passageway to the first conduit and a second aperture fluidly coupling the second passageway to the second conduit.

In another illustrative embodiment, a meter assembly for an agricultural machine comprises: a tank configured to store commodity; a housing supporting the tank and including an inner wall assembly and an outer wall assembly; a meter including a roller positioned in the housing and configured to receive commodity from the tank; a first conduit fluidly coupled to the meter and configured to receive commodity from the roller; and a bypass assembly including at least one passageway fluidly coupled to the meter and the first conduit; wherein the at least one passageway includes a first end fluidly coupled to the meter at one or more locations above the roller and a second end fluidly coupled to the first conduit; and the bypass assembly is defined between the inner wall assembly and the outer wall assembly of the housing.

In some embodiments, the inner wall assembly includes a first section and a second section, with the roller being defined between the first section and the second section, the first section includes a first upper face positioned above the roller and a first lower face positioned below the roller; the second section includes a second upper face positioned above the roller and a second lower face positioned below the roller; and the first and second upper faces cooperate to define boundaries of a processing side of the meter, and the first and second lower faces cooperate to define boundaries of an exhausting side of the meter.

In some embodiments, the at least one passageway is coupled to the processing side of the meter; and the first conduit is fluidly coupled to the exhausting side of the meter. In some embodiments, the at least one passageway includes a first passageway and a second passageway; the first end of the bypass assembly includes at least one aperture fluidly coupling the first and second passageways to the processing side; the second end of the bypass assembly includes a first aperture fluidly coupling the first passageway to the first conduit and a second aperture fluidly coupling the second passageway to a second conduit; and the second conduit is fluidly coupled to the exhausting side of the meter and configured to receive commodity from the roller.

In another embodiment of the present disclosure, a method of using a meter assembly comprises: rotating a roller of a meter, the roller having a plurality of cavities configured to receive and release commodity; conveying commodity along a commodity path, the commodity path including: (i) a processing side of the meter defined above the roller, (ii) at least one cavity of the roller, (iii) an exhausting side of the meter defined below the roller, and (iv) a plurality of conduits fluidly coupled to the exhausting side of the meter; and facilitating air flow through at least one passageway that is substantially devoid of commodity and fluidly coupled to the processing side of the meter and the plurality of conduits. The at least one passageway is coupled to the plurality of conduits upstream of where the plurality of conduits couple to the exhausting side of the meter.

In some embodiments, the method of using a meter assembly further comprises: delivering commodity from a tank to the plurality of cavities of the roller; the tank is coupled to a housing of the meter; and the roller and the at least one passageway are position in the housing of the meter.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments described herein and illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated devices and methods, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

An air or pneumatic seeder20is shown inFIG.1towed by a tractor or prime mover22. The seeder20includes an air cart24, also known as a commodity cart, having one or more tanks for one or more commodities to be applied to the soil, and a drill or implement26which applies the commodity to the soil. The drill has a plurality of ground engaging tools28. The cart24is shown with four tanks30,32,34, and36mounted on a frame38. The frame38is supported on a rear axle40having wheels/tires42at the rear of the frame38. Depending on the cart configuration, additional axles may be provided, such as front axle44and wheels/tires46. The axles and wheels support the cart frame38for movement over the ground surface towed by tractor22. Any number of tanks can be provided on the air cart. The term “cart” should be broadly construed to include any device towed by a prime mover that is supported on one or more axles, such as a trailer, wagon, cart, implement, etc.

The drill26includes a frame48supported by ground wheels50and is connected to the rear of the tractor22by a tongue52. As shown, the cart24is known as a “tow behind” cart meaning that the cart follows the drill. In alternative arrangements, the cart may be a “tow between” cart meaning that the cart is between the tractor22and drill26. In yet a further possible arrangement, the air cart and drill can be combined onto a common frame. The tanks30,32,34, and36can be any suitable device for holding a material or commodity such as seed or fertilizer to be distributed to the soil. The tanks could be hoppers, bins, boxes, containers, etc. The term “tank” shall be broadly construed herein. Furthermore, one tank with multiple compartments can also be provided.

A pneumatic distribution system35includes a fan located behind the front tires46, connected to a product delivery conduit structure having multiple product flow conduits54. The fan directs air through the conduits54. A product meter assembly56is located at the bottom of each tank and delivers product from the tanks at a controlled rate to the conduits54and the air stream moving through the conduits54.

Each conduit54carries product in the air stream to a secondary distribution tower58on the drill26. Typically, there will be one tower58for each conduit54. Each tower58includes a secondary distributing manifold60located at the top of a vertical tube. The distributing manifold60divides the flow of product into a number of secondary distribution lines62. Each secondary distribution line62delivers product to one of a plurality of ground engaging tools28which opens a furrow in the soil and deposits the product therein. The number of conduits54may vary from one to eight or ten or more, depending on the configuration of the cart and drill. Depending on the cart and drill, there may be two distribution manifolds in the air stream between the meters and the ground engaging tools. Alternatively, in some configurations, the product is metered directly from the tank into secondary distribution lines62leading to the ground engaging tools28without an intermediate distribution manifold.

A firming or closing wheel64associated with each tool28trails the tool and firms the soil over the product deposited in the soil. Various types of tools28may be used including, tines, shanks, disks, etc. The tools28are movable between a lowered position engaging the ground and a raised position above the ground. Each tool may be configured to be raised by a separate actuator. Alternatively, multiple tools28may be mounted to a common rockshaft for movement together. In yet another alternative, the tools28may be fixed to the frame38and the frame38raised and lowered by linkages on each of the drill wheels50.

Referring now to the illustrative embodiment shown inFIG.2, a schematic view of a meter assembly200is shown. The meter assembly200may have a reservoir or tank202coupled to a meter204. The tank202may be any of the tanks30,32,34, and36and be sized to contain commodity therein and direct the commodity to the meter204. Commodity may refer to seed, fertilizer, or other nutrients and the like that promote growing a crop. The meter204may be representative of the product meter assembly56. Further, the meter204may selectively distribute commodity from the tank202to a first or second conduit206,208. In one aspect of this disclosure, the meter204may have a run selector, flapper, or the like that is selectively repositionable to distribute commodity from the tank202into either one of the first conduit206or the second conduit208depending on the position of the flapper. This is described in greater herein with reference toFIG.6.

While two conduits206,208are illustrated herein, this disclosure contemplates embodiments with more than two conduits coupled to the meter204. Further still, there may be only one conduit coupled to the meter204. As will be understood in view of this disclosure, the teachings discussed herein are applicable to meters having any number of conduits coupled thereto.

In illustrative embodiments, the tank202may have an agitator210positioned in or on the tank202. The agitator210may be a rotary agitator having extensions that extend radially away from a rotation axis. The agitator210may interact with the tank202to agitate any commodity therein to ensure the commodity is properly fed into the meter204. While a rotary agitator is discussed herein, this disclosure contemplates any known commodity agitator for the agitator210.

In illustrative embodiments, the meter204may have a housing203shaped to surround or enclose certain other components of the meter204and/or the meter assembly200. In illustrative embodiments, the meter204may have a roller218positioned within the housing203. The roller218may selectively distribute commodity from an inlet220to an outlet222of the housing203. The roller218may rotate about an axis and have a plurality of cavities604(seeFIGS.5and6) spaced circumferentially there about. Each of the plurality of cavities604may have a radially distal opening that allows commodity to enter and exit each of the plurality of cavities604as the roller218rotates. Accordingly, commodity positioned at the inlet220may fall by gravity and/or by air flow into one of the cavities604of the roller218as the roller218rotates. Next, as the roller cavity604having the commodity rotates about its axis towards the outlet222, the commodity may fall out of the cavity604as gravity, radial forces, and/or air flow move the commodity towards the outlet222. Accordingly, the commodity may be distributed in a metered fashion from the inlet220to the outlet222by the roller218.

More specifically, the meter204may be designed to process commodity along a commodity path212from the tank202to the conduits206,208. The commodity path212may be the typical path of the commodity as the roller218rotates to transfer commodity from the tank202to the conduits206,208. For example, the commodity path212may the cavities604of the roller218, a processing side214of the meter204, and an exhausting side216of the meter204. The processing side214of the meter204is the location wherefrom the cavities604of the roller218are expected to receive commodity as the roller218rotates. The exhausting side216of the meter204is the location where to the cavities604of the roller218typically release commodity under proper operating conditions. In the illustrative embodiment, the processing side214of the meter204is positioned above the roller218, and the exhausting side216of the meter204is positioned below the roller218. In the illustrative embodiment, the processing side214of the meter204is positioned between the tank202and the roller218. Further, the exhausting side216of the meter204is positioned between the meter204and the conduits206,208.

In some embodiments, the meter assembly200is not a positive displacement meter, and it has been demonstrated that this type of meter assembly200is sensitive to air pressure differentials across the meter204. Therefore, there is a need to balance the pressure across the meter204and pressurize the tank202through the meter204. While one solution is to allow the needed pressure balancing to occur through the flow path of the commodity212, this may result in a slowed rate of air flow due to interference by the commodity. Therefore, another solution is to introduce a dedicated path or bypass to facilitate pressure balanced air flow across the meter204, as described below.

In illustrative embodiments, the meter assembly200may include a bypass assembly224. The bypass assembly224forms at least one continuous passageway from the processing side214or the tank202to at least one of the conduits206,208. The bypass assembly224does not include or pass through the cavities604of the roller218. The bypass assembly224communicates air flow between the tank202and the conduits206,208substantially without the interference from commodity that is passing along the commodity path212. In other words, the bypass assembly224is substantially devoid of commodity. Without interference from the roller218and the commodity, the bypass assembly224effectively balances or equalizes pressure on opposing sides214,216of the roller218.

In the illustrative embodiment shown inFIG.2, the bypass assembly224includes a first side226fluidly coupled to the processing side214and second side228fluidly coupled to the conduits206,208. In the illustrative embodiment, the bypass assembly224includes a y-shaped split229between the first side226and the second side228. The second side228includes a first leg230fluidly coupled to the conduit206and a second leg232fluidly coupled to the conduit208. The first leg230includes a first valve234therein, and the second leg232includes a second valve236therein. The valves234,236are positioned in parallel. The first and second valves234,236may be, for example, butterfly valves or any other valve suitable for opening and closing to form an air-tight seal on opposing sides thereof. The valves234,236may be operated independently from one another, either manually or with a controller (not shown) to facilitate or prevent communication between: (a) the one or more conduits206,208and (b) the processing side214and the tank202of the meter assembly200. It should be appreciated that whileFIG.2shows the first side226of the bypass assembly224opening to the processing side214, the first side226of the bypass assembly224may also open directly to the tank202.

As shown inFIG.2, in the illustrative embodiment, air flows through the conduits206,208in the direction indicated by the arrow211. The bypass assembly224is fluidly coupled to the conduits206,208at a location along the conduits206,208that is upstream of the location where the meter204is fluidly coupled to the conduits206,208. This ensures that air flow from the conduits206,208to the meter204does not recirculate commodity received by the conduits206,208.

In some embodiments, the meter assembly200may include an isolation mechanism213configured to prevent commodity from entering the bypass assembly224. The isolation mechanism213may be, for example, a deflector and/or a filter. In embodiments in which the isolation mechanism213is a deflector, the deflector extends into the processing side214to deflect commodity away from the bypass assembly224to the roller218. In embodiments in which the isolation mechanism213is a filter, the filter allows the passage of air flow and prevents the passage of commodity between the processing side214of the meter204and the bypass assembly224.

In the illustrative embodiment shown inFIG.2, the bypass assembly224is disposed outside the housing203. The bypass assembly224also may be disposed within the housing as shown in the illustrative embodiment depicted inFIGS.3-6. Although some components in the schematic views ofFIGS.2and3are not drawn to scale, it should be appreciated that identical reference numbers are used to identify the same components inFIGS.2and3and otherwise herein.

FIG.3illustrates a meter assembly300. As shown inFIG.3, the housing203includes an inner wall assembly238and an outer wall assembly240. The roller218is positioned inward of the inner wall assembly238. The bypass assembly224is positioned outward of the inner wall assembly238and between the inner wall assembly238and the outer wall assembly240.

In the illustrative embodiments shown inFIGS.2and3, the bypass assembly224includes a y-shaped split229connecting the legs230and232. In some embodiments, the legs of the bypass assembly are not connected. For example, in the illustrative embodiment shown inFIGS.4and6, a first leg430and a second leg432are separate and distinct legs that each form a continuous path fluidly coupling the conduits206,208to the processing side214or the tank202of the meter assembly200.

FIG.4illustrates a meter assembly400. As shown inFIG.4, the meter assembly400includes a bypass assembly424that does not include or pass through the cavities604of the roller218. The bypass assembly424communicates air flow between the tank202and the conduits206,208substantially without the interference from commodity that is passing along the commodity path212. The presence of the bypass assembly424effectively balances or equalizes pressure on opposing sides214,216of the roller218. The bypass assembly424is positioned inside the housing203. Specifically, the bypass assembly424is positioned between the inner wall assembly238and the outer wall assembly240of the housing203.

In the bypass assembly424, the legs430and432may be referred to as discrete passageways430and432each extending from a first side426to a second side428of bypass assembly424without connecting to one another. In other words, each passageway430,432has its own inlet aperture and its own outlet aperture. Similar to the bypass assembly224, the bypass assembly424is arranged such that the first side426is fluidly coupled to the processing side214or the tank202and second side428is fluidly coupled to the conduits206,208. In other words, a first side of each passageway430,432is coupled to the processing side214or the tank202, a second side of each passageway430,432is coupled to the conduits206,208.

As shown inFIG.4, in the illustrative embodiment, air flows through the conduits206,208in the direction indicated by the arrow211. The bypass assembly424is fluidly coupled to the conduits206,208at a location along the conduits206,208that is upstream of the location where the meter204is fluidly coupled to the conduits206,208. This ensures that air flow from the conduits206,208to the meter204does not recirculate commodity received by the conduits206,208.

In some embodiments, the meter assembly400may include isolation mechanisms213,215configured to prevent commodity from entering the bypass assembly424. The isolation mechanisms213,215may be, for example, deflectors and/or filters213,215. In embodiments in which the isolation mechanism213,215are deflectors, the deflectors extend into the processing side214to deflect commodity away from the bypass assembly424to the roller218. In embodiments in which the isolation mechanism213,215are filters, the filters allow the passage of air flow and prevent the passage of commodity between the processing side214of the meter204and the bypass assembly424.

Referring now toFIG.5, the meter assembly400is depicted showing the meter204separated from the tank202, conduits206,208, and other portions of the seeder20. Specifically,FIG.5shows a perspective view of the roller218disposed in the housing203. The roller218is positioned between opposing faces of the inner wall assembly238, as will be described in greater detail below. The meter204and/or the housing203of the meter204may have an inlet220, an outlet222, and the roller218is positioned between the inlet220and the outlet222as discussed herein. The roller218may have a roller shaft606that extends through an orifice of the meter housing203. The roller shaft606is coupled to a roller motor (not shown) to drive rotation of the roller shaft606, and thus, the roller218. The roller motor may be an electrical, hydraulic, or pneumatic motor that selectively rotates the roller218. The outer wall assembly240of the meter housing203is positioned outside and adjacent to corresponding portions of the inner wall assembly238, as will be described in greater detail with respect toFIG.6.

Referring now toFIG.6, a partial section view is shown. As shown inFIG.6, the housing203includes an inner wall assembly238and an outer wall assembly240. The inner wall assembly238includes a plurality of sections and each section includes a plurality of faces. For example, the inner wall assembly238includes a first section241extending vertically the length of the housing203from the inlet220to the outlet222. The inner wall assembly238also includes a second section243spaced apart from the first section241and extending vertically the length of the housing203from the inlet220to the outlet222. The roller218is positioned between the first section241and the second section243of the inner wall assembly238. The first section241of the inner wall assembly238includes, for example, an upper face242positioned above the roller218and a lower face244positioned below the roller218. The second section243of the inner wall assembly238includes, for example, an upper face246positioned above the roller218and a lower face248positioned below the roller218. The opposing upper faces242,246cooperate to define boundaries of the processing side214of the meter204. The lowering opposing faces244,248cooperate to define boundaries of the exhausting side216of the meter204.

In the illustrative embodiment, the meter204includes a flapper702. The flapper702is pivotally coupled to the housing203, either directly or through a manifold coupled to the housing203, to pivot about a flapper axis704between a first position and a second position. In the first position (not shown) a distal end706of the flapper702abuts the first section241to direct commodity to one of the conduits206,208. In the second position (seeFIG.6) the distal end of the flapper702abuts the second section243to direct commodity to the other of the conduits206,208.

The position of the flapper702may be selectively controlled by a flapper arm708. More specifically, the flapper arm708may be coupled to an actuator or the like to selectively pivot the flapper702between the first position and the second position. While a flapper702is illustrated coupled to the housing203as discussed herein, this disclosure considers positioning the flapper702in a manifold coupled to the meter housing as well. In this configuration, the flapper702and corresponding components may be positioned in the manifold which can be selectively coupled to the housing203. Further still, this disclosure also considers utilizing a turret type run selector. The turret style run selector may be a rotary run selector that alters the flow path of commodity as it rotates about a rotation axis. Accordingly, this disclosure contemplates utilizing different types of run selectors either coupled directly to the meter housing203or to a manifold coupled thereto.

Referring still toFIG.6, the meter housing203may be a molded material, such as plastic, and formed from two separate sections coupled to one another. The meter housing203may form a passageway for commodity between the inlet220and the outlet222that is metered by the rotation of the roller218. As described above, the passageway for commodity may be referred to as a commodity path212. The commodity path212may include the cavities604of the roller218, and therefore, the commodity path212, like the roller218, is positioned between opposing sections241,243of the inner wall assembly238.

As shown inFIG.6, the discrete passageways430and432are positioned between the inner wall assembly238and the outer wall assembly240. For example, the discrete passageway430may be defined between the first section241of the inner wall assembly238and a first portion245of the outer wall assembly240. The discrete passageway432may be defined between the second section243of the inner wall assembly238and a second portion247of the outer wall assembly240. As shown inFIG.6, the first section241of the inner wall assembly238is adjacent the first portion245of the outer wall assembly240, and second section243of the inner wall assembly238is adjacent the second portion247of the outer wall assembly240.

In the illustrative embodiment, the discrete passageway430includes (at one end) an aperture250defined in the upper face242of the inner wall assembly238. The aperture250opens into the processing side214. In some embodiments, the aperture250opens directly into the tank202, as described herein. The discrete passageway430includes (at the other end) an aperture252defined in the lower face244of the inner wall assembly238. The aperture252opens into the exhausting side216.

In the illustrative embodiment, the discrete passageway432includes (at one end) an aperture254defined in the upper face246of the second section243of the inner wall assembly238. The aperture254opens into the processing side214. In some embodiments, the aperture254opens directly into the tank202, as described herein. The discrete passageway432includes (at the other end) an aperture256defined in the lower face248of the inner wall assembly238. The aperture256opens into the exhausting side216. It should be appreciated that the discrete passageways430and432are in fluidly coupled to the conduits206,208respectively (although not shown inFIG.6, seeFIG.4). As such, additional tubes, pipes, or other walled structures may fluidly couple the apertures252,256to the conduits206,208or the apertures252,256may open directly to the conduits206,208.

WhileFIG.6illustratively shows apertures250,252,254,256opening direct to cavities defined between sections of the inner wall assembly238and portions of the outer wall assembly240, it should be appreciated that in some embodiments, the apertures250,252,254,256may open instead to additional tubes, pipes, or other walled structures positioned in the space between the inner and outer wall assemblies238,240.

FIG.6illustratively shows: (i) the first passageway430positioned between the first section241of the inner wall assembly238and the first portion245of the outer wall assembly240, and (ii) the second passageway432positioned between the second section243of the inner wall assembly238and the second portion247of the outer wall assembly240; however, in some embodiments, the first and second passageways430,432may both be positioned either: (a) between the first section241of the inner wall assembly238and the first portion245of the outer wall assembly240, or (b) between the second section243of the inner wall assembly238and the second portion247of the outer wall assembly240. In that case, the passageways430,432may have a single aperture positioned at the first end of the bypass assembly (similar toFIG.3) and/or one aperture for each corresponding conduit206,208positioned at the second end of the bypass assembly.

In any event, the one or more apertures at the first end426of the bypass assembly424open to one or more locations above the roller218, and the passageways430,432are each fluidly coupled (at the second end428of the bypass assembly) to a separate conduit206,208.

It should be appreciated that, in some embodiments, each passageway is fluidly coupled to a separate conduit206,208, so that the conduits206,208can be pressurized or depressurized selectively and independently by virtue of being isolated from one another.