Rotary clamshell gate actuator for bulk material container

In accordance with presently disclosed embodiments, systems and methods for managing dry bulk material efficiently at a well site or other location are provided. Present embodiments are directed to a rotary clamshell gate actuation system and method, where the gate is separate from the one or more actuators used to open/close the gate. The disclosed system may include a portable bulk material container with a clamshell gate for easily dispensing material from the container. The system also includes a support structure equipped with one or more rotary actuators used to actuate the clamshell gate of the container between a closed and open position when the container is positioned on the support structure. The disclosed clamshell gate actuation system is easy to operate, low cost to manufacture, and reliable even when the portable container is not precisely aligned on the support structure.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a U.S. National Stage Application of International Application No. PCT/US2015/041581 filed Jul. 22, 2015, which is incorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

The present disclosure relates generally to transferring dry bulk materials, and more particularly, to a support structure with an actuator for opening/closing a rotary clamshell gate of a portable bulk material container.

BACKGROUND

Bulk material handling systems are used in a wide variety of contexts including, but not limited to, drilling and completion of oil and gas wells, concrete mixing applications, agriculture, and others. In existing bulk material handling applications, dry material (e.g., sand, proppant, gel particulate, dry-gel particulate, aggregate, feed, and other solid materials) may be transported in a number of ways. In the formation of wellbore treatment fluids, for example, bulk material is often transferred between transportation units, storage tanks, blenders, and other on-site components via pneumatic transfer, sand screws, chutes, conveyor belts, and other components.

Recent developments in bulk material handling operations involve the use of portable containers for transporting dry material about a well location. The containers can be brought in on trucks, unloaded, stored on location, and manipulated about the well site when the material is needed. The containers are generally easier to manipulate on location than a large supply tank trailer. The containers are eventually emptied by dumping the contents thereof to a desired destination.

In traditional container-based bulk material transfer, portable containers generally include a discharge gate at the bottom of the container that can be actuated to empty bulk material from the container at a desired time and location. In applications where several portable containers are used throughout an operation, it is desirable to utilize containers with discharge gates that are both easy to actuate and low cost to manufacture.

DETAILED DESCRIPTION

Certain embodiments according to the present disclosure may be directed to systems and methods for managing dry bulk material efficiently at a well site or other location. The systems and methods may involve the use of portable containers of bulk material (e.g., pre-filled containers or filled on location) designed to output bulk material through a specially actuated rotary clamshell gate. The disclosed techniques may be used to efficiently handle any bulk material having a solid constituency including, but not limited to, sand, proppant, gel particulate, dry-gel particulate, aggregate, feed, and others.

In currently existing bulk material handling applications, dry material may be transported in a number of ways. In the formation of wellbore treatment fluids, for example, the bulk material is often transferred between transportation units, storage tanks, blenders, and other on-site components via pneumatic transfer, sand screws, chutes, conveyor belts, and other components. Recently, a new method for transferring sand, or proppant, to a hydraulic fracturing site involves using portable bulk material containers to transport the dry material. The containers can be brought in on trucks, unloaded, stored on location, and manipulated about the well site when the material is needed. These containers generally include a discharge gate (e.g., swing gate, knife gate, or linear actuated clamshell gate) at the bottom that can be actuated to empty the dry material contents of the container at a desired time and location.

In order to reduce the cost and complexity of the containers themselves, actuators (i.e., devices used to actuate the discharge gate) can be attached to a separate support structure and designed to interface with the discharge gate of whatever container is placed onto the support structure. Although discharge gates can take many forms, in such systems the containers feature a type of discharge gate known as a “knife gate”, as these are the simplest gates to interface with a separate actuator. A knife gate generally relies on horizontal actuation via an actuator to slide the gate horizontally out of the way, thereby forming an opening in the bottom of the container through which bulk material can exit. Unfortunately, knife gates have certain limitations, such as needing very tight manufacturing tolerances to form a complete seal when used with sand and similarly fine bulk material particles. These tight tolerances increase the cost of manufacturing such gates.

Rotary clamshell gates are generally more reliable and cheaper to manufacture than knife gates when used to store and release relatively fine bulk material particles. This is because clamshell gates do not rely on a metal-to-metal seal to block the flow of bulk material when the gate is closed. Instead, the bulk material itself creates a seal between the opening in the bottom of the container and the top of the clamshell gate when the gate is positioned over the opening.

Clamshell gates are routinely used in stationary bulk material containers as well as some transportable containers (e.g., belly-dump trailers and rail cars). In existing systems, clamshell gates are often opened and closed using a pivoting linear actuator. In general, these actuators are integral to the structure of the clamshell gate and the container. That is, the clamshell gate actuators are usually fixed between a stationary portion of the container and the movable clamshell gate and activated to move the clamshell gate between an open and a closed position. This is a relatively complicated setup that can increase the cost of manufacturing the individual containers, each having integral gate actuators.

The bulk material container handling systems disclosed herein are designed to address and eliminate the shortcomings associated with existing containers and gate actuators. Present embodiments are directed to a rotary clamshell gate actuation system and method, where the gate is separate from the one or more actuators used to open/close the gate. The disclosed system may include a portable bulk material container with a clamshell gate for easily dispensing material from the container. The system also includes a support structure equipped with one or more rotary actuators used to actuate the clamshell gate of the container between a closed and open position when the container is positioned on the support structure.

The disclosed systems and methods leverage the operational advantages of the clamshell gate with the ease of actuation of a horizontal knife gate. The clamshell gate enables more reliable gate operation for dispensing dry bulk material at a lower cost than conventional knife gates since no metal-to-metal seals are needed to prevent sand or other dry bulk material from falling through the gate once it is closed. The container is also cheaper to manufacture than existing clamshell gate containers since the gate actuators are provided on the support structure and therefore are entirely separate from the container. Furthermore, the specific design of the rotary actuators and the rotary clamshell gate on the container may enable accurate operation of the gate system even when the container is not aligned precisely with the support structure.

Turning now to the drawings,FIG. 1is a block diagram of a bulk material handling system10. The system10includes a container12elevated on a support structure14and holding a quantity of bulk material. The container12may utilize a gravity feed to provide a controlled, i.e. metered, flow of bulk material at an outlet16.

The outlet16may be a gravity feed outlet that transfers the bulk material from the container12to any desired location. In embodiments where the bulk material handling system10is used at a well treatment site, the outlet16may transfer the bulk material from the container12to a blender. The blender may mix the bulk material with water and other additives to form a fluid mixture (e.g., fracing fluid, cement slurry, drilling mud) for use at the treatment site. It should be noted that the disclosed system10may be used in other contexts as well. For example, the bulk material handling system10may be used in concrete mixing operations to dispense aggregate from the container12through the outlet16into a concrete mixing apparatus. In the agricultural industry, the bulk material handling system10may be used to transport and dispense various feeds through the outlet16of the container12. Still other applications may be realized for transporting dry bulk material via the container12to an elevated location on a support structure14and dispensing the bulk material in a metered fashion through the outlet16.

As illustrated, the container12may be elevated above an outlet location via the support structure14. In some embodiments, the support structure14may be configured to support multiple containers12, instead of just one. In any case, the container(s)12may be completely separable and transportable from the support structure14, such that any container12may be selectively removed from the support structure14and replaced with another container12. That way, once the bulk material from the container12runs low or empties, a new container12may be placed on the support structure14to maintain a steady flow of bulk material to an outlet location. In some instances, the container12may be closed before being completely emptied, removed from the support structure14, and replaced by a container12holding a different type of bulk material to be provided to the outlet location.

A portable bulk storage system18may be provided at a site for storing one or more additional containers12of bulk material to be positioned on the support structure14for outputting material through the outlet16. The bulk material containers12may be transported to the desired location on a transportation unit (e.g., truck). The bulk storage system18may be the transportation unit itself or may be a skid, a pallet, or some other holding area. One or more containers12of bulk material may be transferred from the storage system18onto the support structure14, as indicated by arrow20. This transfer may be performed by lifting the container12via a hoisting mechanism, such as a forklift or a crane, or a specially designed container management device.

After one or more of the containers12on the support structure14are emptied, the empty container(s)12may be removed via a hoisting mechanism. In some embodiments, the one or more empty containers12may be positioned on another bulk storage system18(e.g., a transportation unit, a skid, a pallet, or some other holding area) until they can be removed from the site and/or refilled. In other embodiments, the one or more empty containers12may be positioned directly onto a transportation unit for transporting the empty containers12away from the site. It should be noted that the same transportation unit used to provide one or more filled containers12to the location may then be utilized to remove one or more empty containers12from the location.

As illustrated, the containers12may each include a rotary clamshell gate22for selectively dispensing or blocking a flow of bulk material from the container12. When the rotary clamshell gate22is closed, as shown, the gate22may prevent bulk material from flowing from the container12to the outlet16. The rotary clamshell gate22may be selectively actuated into an open position (not shown) to release the bulk material from the container12into the outlet16. This actuation generally involves rotating the rotary clamshell gate22about a pivot point24relative to the container12to uncover an opening26at the bottom of the container12, thereby allowing bulk material to flow through the opening26and into the outlet16. When it is desired to stop the flow of bulk material, or once the container12is emptied, the rotary clamshell gate22may then be actuated (i.e., rotated) back to the closed position to block the flow of bulk material.

In presently disclosed embodiments, the support structure14includes one or more actuators28used to actuate the rotary clamshell gate22of whatever container12is positioned on the support structure14. The one or more actuators28may be entirely separate from the container12and its corresponding rotary clamshell gate22. That is, the one or more actuators28and the rotary clamshell gate22are not collocated on the same structure. The same one or more actuators28may be used to open and/or closed the rotary clamshell gates22of multiple containers12that are positioned on the support structure14over time. As described in detail below, the one or more actuators28may be rotary actuators, not linear actuators, for engaging and moving the rotary clamshell gate22between closed and open positions.

FIG. 2is a more detailed side view of the transportable container12with the rotary clamshell gate22being opened by the rotary actuator28. As noted above, the rotary actuator28is not part of the container12or the rotary clamshell gate22; instead, the rotary actuator28is part of the support structure14(indicated by a dashed line inFIG. 2). The rotary actuator28may be disposed on an inner surface of the support structure14facing toward the container12when the container12is disposed on the support structure14. As shown, the rotary actuator28may be positioned to engage and move the rotary clamshell gate22into an open position. In this open position, the rotary clamshell gate22is rotated off to the side, exposing the opening26at the bottom of the container12.

As mentioned above, the rotary clamshell gate22may be used in the transportable bulk material container12to provide low-cost and effective sealing of the bulk material within the container12throughout its transportation. When closed, the clamshell gate22operates to seal bulk material within the container12without relying on a metal-to-metal seal between container components. The clamshell gate22may cover the container opening26and slope upward along both side of the container opening26to prevent bulk material from escaping the container12. The bulk material particles may flow into the space between the opening26and the upward sloping clamshell gate22, but the particles cannot travel upward to escape the space between the opening26and the clamshell gate22. The bulk material trapped between the opening26and the gate22may create a self-seal due to the angle of repose of the material, thereby keeping the bulk material within the container12. As such, the clamshell gate22may be more reliable and durable for sealing bulk material within the container12as compared to other gates (e.g., knife gates) that rely on tight mechanical tolerances between the gate and the container housing.

The clamshell gate22described herein may be actuated into the open position via the rotary actuator28that is part of the support structure14. As illustrated, the rotary actuator28may include at least one extension arm50that is rotatable about a pivot point52of the support structure14. The rotary clamshell gate22may include an engagement feature54designed to be contacted by the rotating extension arm50of the actuator28. As the actuator28rotates the arm50about the pivot point52, the arm50may engage and push against the engagement feature54, thereby pushing the rotary clamshell gate22so that it rotates about the pivot point24of the container12. In this manner, the actuator28is able to transition the rotary clamshell gate22from a closed position to the illustrated open position.

In some embodiments, the engagement feature54may include a lateral protrusion extending outward from the rotary clamshell gate22. In other embodiments, the engagement feature54may include a roller (e.g., roller bearing disposed over a lateral protrusion) extending outward from the rotary clamshell gate22. Adding a roller bearing or similar roller mechanism to the engagement feature54may facilitate a relatively smooth transition of rotary force from the arm50to the rotary clamshell gate22. Regardless of the exact type of engagement feature used, a frictional force between the rotating arm50and the engagement feature54is used to actuate the rotary clamshell gate22between the closed and open positions.

In the illustrated embodiment, the engagement feature54may be disposed on the rotary clamshell gate22at a position above a lower surface56of the rotary clamshell gate22. The term “lower surface”56refers to the bottom-most portion of the rotary clamshell gate22extending downward away from the rest of the container12and toward the support structure14. This may enable the actuator28to interface directly with the rotary clamshell gate22while allowing the lower surface56of the rotary clamshell gate22to extend as far as possible downward from the container12. This lower positioning of the rotary clamshell gate22relative to the container12may help to provide a better gravity feed of bulk material exiting the container12while producing less dust.

In some embodiments, the actuator arm50may only interact with the rotary clamshell gate22through a frictional contact between the arm50and the engagement feature54(e.g., protrusion, roller, etc.). Thus, the actuation of the rotary clamshell gate22via the actuator28does not rely on the interaction of additional pins, latches, or fasteners. This frictional engagement and actuation of the rotary clamshell gate22may enable effective operation of the actuator28even when the container12is slightly misaligned with the support structure14.

It may be desirable for the actuator28to be capable of handling misalignment between the actual placement and the desired placement of the container12on the support structure14. That way, if the container12is not precisely placed on the support structure14, the actuator28may still be able to properly actuate the rotary clamshell gate22between the closed and open positions. To that end, the engagement feature54may extend far enough in a direction perpendicular to the side surface of the rotary clamshell gate22that the rotary actuator28would still be able to contact the engagement feature54if the container12were misaligned in the direction of the X-axis. Similarly, the rotary arm50may extend far enough out from the pivot point52to reach the engagement feature54even if the container12were misaligned in the direction of the Y-axis. The system may be designed to handle misalignment of up to approximately 2.5 centimeters in the X-Y plane. As a result, the actuators28may be able to move the rotary clamshell gate22between the closed and open positions even when the container12is not precisely aligned with the support structure.

In some embodiments, the one or more actuators28on the support structure may be activated automatically, via electrical, hydraulic, pneumatic, or optical signaling. The actuators28may be communicatively coupled (e.g., via a wired connection or wirelessly) to a control system58of the bulk material handling system. The control system58may be communicatively coupled to several other well site components including, but not limited to, the blender unit, an automated container management device, and various sensors. The control system58utilizes at least a processor component60and a memory component62to monitor and/or control various operations and bulk material transfer at the well site. For example, one or more processor components60may be designed to execute instructions encoded into the one or more memory components62. Upon executing these instructions, the processors60may provide passive logging of certain operations at the well site, such as the positions of one or more rotary actuators28. In some embodiments, the one or more processors60may execute instructions for controlling operations of certain well site components, such as the position of the one or more actuators28on the support structure14. Upon receiving a predetermined signal (e.g., open, close, neutral) from the control system58, each actuator28may rotate the arm50about the pivot point52until it reaches the desired placement corresponding to the received signal. The processors60may also output signals at a user interface63for instructing operators to remove an empty container from the support structure14and replace the container with a new container holding a certain type of bulk material needed for the well treatment. Other types of instructions for inventory control/monitoring may be provided through the disclosed systems.

FIGS. 3A-3Cillustrate another embodiment of the transportable container12having the rotary clamshell gate22being opened by a rotary actuator28. Again, the rotary actuator28is not part of the container12or the rotary clamshell gate22; instead, the rotary actuator28is part of the support structure14. In the illustrated embodiment, the rotary actuator28may provide the rotary motion needed to move the clamshell gate22from the closed position (FIG. 3A) to the open position (FIG. 3C) using a linear actuation mechanism64(i.e., piston) coupled to a rotatable lever arm66. The linear actuation mechanism64may be operated electrically, pneumatically, or hydraulically to rotate the lever arm66. The linear actuation mechanism may be fixed to a mounting point on the support structure14at one end and coupled to the lever arm66at an opposing end.

As illustrated, the lever arm66may include two portions extending in different directions from a pivot point68. One portion is generally coupled to the piston64and the other portion is designed to contact the engagement feature54as the lever arm66is rotated about the pivot point68. Other embodiments of the lever arm66may be a cam-shaped component, or may take other forms that are rotatable about the pivot point68upon the application of a linear translation force to one portion of the lever arm66.

InFIG. 3A, the rotary actuator28is disposed in a neutral position where the lever arm66is entirely below an upper surface of the support structure14. This may enable an operator (or automated system) to remove the container12from the support structure14and/or to dispose another container12onto the support structure14above the actuator28. When the rotary actuator28is in this position, the rotary clamshell gate22is closed. Upon receiving a desired signal (e.g., from a control system) at the rotary actuator28, the actuator28may extend the linear actuation mechanism64outward, thus rotating the lever arm66about the pivot point68and into an initial engagement with the engagement feature54as illustrated inFIG. 3B. Further extension of the linear actuation mechanism64may continue to rotate the lever arm66, which pushes on the engagement feature54to rotate the rotary clamshell gate22into the open position ofFIG. 3C. Still other types of rotary actuators28may be employed in other embodiments of the disclosed systems, as described in detail below.

FIGS. 4A-4Cprovide a perspective view of the container12with the rotary clamshell gate22being actuated by a set of two rotary actuators28disposed in a neutral position, an open position, and a closed position. In the illustrated embodiment, the support structure (not shown) features two rotary actuators28A and28B for transitioning the rotary clamshell gate22between the closed and open positions. The rotary actuators28A and28B may be disposed on opposite sides of the support structure. One of the actuators28A may be used to engage and urge the rotary clamshell gate22into the open position, while the other actuator28B may be used to return the rotary clamshell gate22to the closed position. Different arrangements and placements of one or more actuators28on the support structure may be utilized in other embodiments, as described below.

FIG. 4Aillustrates the two actuators28disposed in a neutral position. The actuators28may be disposed in the neutral position when neither of the actuators28are being activated (e.g., by control system60ofFIG. 2). In the illustrated embodiment, this neutral position may involve both actuator arms50A and50B being laid down and generally aligned with a horizontal plane of the support structure. However, the neutral position of the actuator arms50A and50B may be different in other embodiments. When the actuators28A and28B are in the neutral position, the corresponding actuator arms50A and50B are positioned so that they do not interfere with the rotary clamshell gate22. As a result, the rotary clamshell gate22is in a closed position when the actuators28A and28B are in the neutral position ofFIG. 4A.

The container12may be loaded onto or unloaded from the support structure when the actuators28A and28B are disposed in the neutral position. As such, it may be desirable for the entire length of both actuator arms50A and50B to be kept below an upper surface of the support structure when they are in the neutral position. This keeps the actuator arms50A and50B out of the way of the container12being lifted onto the support structure. With the actuators28A and28B in the neutral position, an operator has more freedom to load/unload the containers12from the support structure. The actuators28A and28B may initially default to the neutral position, allowing an operator to place the first container12thereon without having to adjust the position of the actuators28A and28B or lift the container12above a certain point.

In the illustrated embodiment, the support structure may include two actuators28A and28B, one to move the rotary clamshell gate22into the open position ofFIG. 4Band the other to move the rotary clamshell gate22back into the closed position ofFIG. 4C. As shown inFIG. 4B, the actuator28A may be activated to rotate the actuator arm50A in a counterclockwise direction (arrow70) with respect to the pivot point52A. The rotating actuator arm50A may then contact and push against a first engagement feature54A on the rotary clamshell gate22. Further movement of the actuator arm50A may rotate the rotary clamshell gate22in a clockwise direction (arrow72) relative to the pivot point24on the container12until the clamshell gate22reaches the open position. In the open position, the rotary clamshell gate22allows bulk material to flow out through the opening in the bottom of the container12. The weight of the bulk material moving through the rotary clamshell gate22, in addition to the actuator28A, may maintain the rotary clamshell gate22in the open position.

To close the rotary clamshell gate22, the actuator28B may be activated to rotate the actuator arm50B in a clockwise direction (arrow74) with respect to the pivot point52B. The rotating actuator arm50B may then contact and push against a second engagement feature54B on an opposite side of the rotary clamshell gate22from the engagement feature54A. Further movement of the actuator arm50B may rotate the rotary clamshell gate22in a counterclockwise direction (arrow76) relative to the pivot point24on the container12until the clamshell gate22reaches the closed position. In the closed position, the rotary clamshell gate22stops the flow of bulk material out of the opening in the bottom of the container12. The weight of the bulk material piled on top of the rotary clamshell gate22may maintain the rotary clamshell gate22in the closed position, allowing the actuator28B to be returned to its neutral position once the gate22is closed.

The actuators28A and28B may each be designed to rotate only a certain amount around their respective pivot points52A and52B. For example, the actuator28A may be rotatable between the neutral position ofFIG. 4Aand the activated position ofFIG. 4B, while the actuator28B may be rotatable between the neutral position ofFIG. 4Aand the activated position ofFIG. 4C.

In some embodiments, the container12may be designed such that the rotary clamshell gate22can be opened/closed by rotating the gate22in only one direction (e.g., clockwise) relative to the pivot point24on the container12. Having two actuators28A and28B disposed on opposite sides of the support structure may enable the system to effectively actuate the rotary clamshell gate22between the closed and open positions, regardless of which way the container12is facing when it is loaded onto the support structure. For example, the actuators28A and28B would still be able to open/close the rotary clamshell gate22if the container12was loaded in an opposite orientation with respect to the support structure as shown inFIGS. 4A-4C. In this opposite orientation, the actuator28B may push against the engagement feature54A to rotate the rotary clamshell gate22into the open position and the actuator28A may push against the engagement feature54B to rotate the rotary clamshell gate22back into the closed position. Thus, having two actuators28A and28B to perform separate opening and closing functions may allow an operator to load the container12onto the support structure from either side.

The illustrated embodiment ofFIGS. 4A-4Cfeatures two actuators28A and28B each designed to actuate the rotary clamshell gate22in a single direction between the closed and open positions. However, other embodiments may include bidirectional actuators designed to actuate the rotary clamshell gate in both directions.FIG. 5schematically illustrates one example of a bidirectional actuator28. The bidirectional actuator28may include two actuator arms50A and50B extending in opposite directions from each other. In the neutral position, the actuator28may be positioned with the actuator arms50A and50B in horizontal alignment, so that the container may be easily moved on and off the support structure. To open the rotary clamshell gate22, the actuator28may rotate in a counterclockwise direction (arrow90) about the pivot point52to bring the first actuator arm50A into contact with the engagement feature54, as shown. To close the rotary clamshell gate22, the actuator28may rotate in a clockwise direction (arrow92) about the pivot point52to bring the second actuator arm50B into contact with the engagement feature54.

FIG. 6illustrates another embodiment of a bidirectional actuator28, similar to the one described with reference toFIG. 5. This bidirectional actuator28may include just a single actuator arm50extending from the pivot point52. The single actuator arm50may be controlled to rotate a full 360 degrees about the pivot point52to open/close the rotary clamshell gate22as shown.

In some embodiments, the bidirectional actuators28described herein may be applied to just one side of the support structure. In other embodiments, two similar bidirectional actuators28may be disposed on opposite sides of the support structure to engage opposing engagement features54of the rotary clamshell gate22at the same time to move the rotary clamshell gate22between the closed and open positions.

In other embodiments, the support structure may include a single actuator28designed to actuate the rotary clamshell gate22into just the open position, and the container12may be equipped with one or more springs to return the gate22to the closed position. In such instances, the springs may only function to close the rotary clamshell gate22once the container12is completely emptied of bulk material. If it is desirable to close the rotary clamshell gate22before the container12is fully emptied, the clamshell gate22may have to be actuated closed via one or more actuators28.

FIG. 7illustrates an embodiment of the container12equipped with springs110for biasing the rotary clamshell gate22toward the closed position. The springs110may include linear springs, torsional springs, compression springs, or some other biasing mechanism. As illustrated, the springs110may be used to couple both sides of the rotary clamshell gate22to two other locations112on the container12. In other embodiments, one or more springs110may couple just one side of the rotary clamshell gate22to another location112on the container12. The springs110can be attached to different locations112on the container12than those illustrated inFIG. 7.

FIG. 8illustrates an embodiment of the rotary clamshell gate22with features that enable relatively easy manipulation of the gate22. First, the rotary clamshell gate22may include a manual actuation engagement feature130for enabling manual actuation of the rotary clamshell gate22in the event that one or more of the automated actuators (28) are not operating properly. The manual actuation engagement feature130, as illustrated, may be a piece of hollow tubing coupled to an end of the rotary clamshell gate22. An operator may slide a bar into the tubing and use the bar to lift the rotary clamshell gate22into a desired orientation. In presently disclosed embodiments, the automatic rotary actuators are coupled to the support structure and completely separate from the rotary clamshell gate22. As a result, an operator may only have to overcome the weight of the gate22itself to manipulate the gate into a desired position, without having to overcome any additional force from actuator system.

InFIG. 8, the radius of curvature of the lower surface56of the rotary clamshell gate22is approximately equal to a swing radius R through which the rotary clamshell gate22is designed to rotate relative to the pivot point24during opening/closing. This may be particularly desirable in instances where the container releases bulk material into a gravity-fed pile of bulk material extending through a chute below the rotary clamshell gate22. By making the radius of curvature of the lower surface56approximately equal to the swing radius R, the rotary clamshell gate22may be able to cut through this pile of bulk material during opening/closing motions without fighting a large amount of drag in either direction. This reduces the torque output required by the one or more actuators used to move the rotary clamshell gate22.

In addition, the rotary clamshell gate22may include various other structural reinforcements that help reduce the amount of torque on the actuator(s) of the system. The illustrated clamshell gate22includes a number of reinforcement ribs132disposed along the bottom of the rotary clamshell gate22. These ribs132may provide increased torsional support to the rotary clamshell gate22, particularly in embodiments where the rotary clamshell gate22is elongated and actuated from one end at a time. In this way, the ribs132may provide additional stability for the rotary clamshell gate22as it is actuated between the closed and open positions.