Abstract: A pipe storage system can include a plurality of pipe storage bays established between adjacent pipe storage arms, a plurality of protrusions extending from the pipe storage arms into each pipe storage bay, the plurality of protrusions establishing a plurality of channels, wherein each channel is established between a pair of adjacent protrusions, and a plurality of latches, wherein the latches are movable from between a retracted position in which the latches are retracted to establish series of first pipe storage openings between opposing channels and an extended position in which the latches extend into the pipe storage bay to establish a series of second pipe storage openings between opposing protrusions.

Abstract: An apparatus for separating solids from solids laden drilling fluid is provided. The apparatus includes a shale shaker and a screen assembly. The shale shaker includes a base and a basket isolated from the base, a flow tray arranged in the basket for directing screened drilling fluid. The screen assembly includes at least one layer of screening material, a screen support having a perimeter with at least one support point within the perimeter, wherein the flow tray includes at least one raised portion to support the screen assembly. In some versions the shale shaker has a basket having side supports and at least one intermediate support arranged between the side supports. The screen assembly includes a screen support supporting at least one layer of screening material.

Abstract: A process for the manufacture of thin-walled elasto-porous elements in the form of bushings in metal-rubber material (MR), comprises the steps of: obtaining wire fragments in the form of spirals having a lead equal to the spiral diameter, forming a flat blank from said spiral segments; pressing the blank into a roll; placing the roll into a mold; placing some elastic medium inside said roll; and pressing the roll in several passes by axial compression together with the elastic medium elements transforming the axial compression into radial pressure on the roll to be compressed.

Abstract: A screen for intake of fluid. The screen includes parallel and spaced rods, filtration material, a fitting, and structural members. The rods may be distributed in a cylindrical configuration. The filtration material, in some embodiments spirally wrapped wire, is disposed around the rods to define an interior volume. The fitting is disposed at an end of the rods and adjacent to the filtration material. Each structural member, which in some embodiments are elongated bars, is interposed between adjacent rods. The structural members are welded to the adjacent rods, and the adjacent rods and the structural members are welded to the fitting to increase the effective weld area, the tensile strength of the connection, and potentially the overall strength of the screen. The screen may be used for a variety of fluids and installations, and is particularly suited to use in water wells.

Abstract: A compact mobile variable angle vibrating screen with a suspension and dampening system configured to rapidly accommodate variable angles and exhibit acceptable vibration levels; especially during power up and power down surge vibration at the variable angles. The system comprises a group of bi-directional dual pivot leg vibration damper mechanisms, including nesting tubes, one with holes for receiving pins and the other with a semi-circular cutout at the bottom edge.

Abstract: A screen system having a plurality of screen elements that can be readily removed and replaced to vary one or more characteristics of the screen surface formed by the screen system. The screen system includes a support system for supporting at least one screen element to prevent deformation of the screen element that typically would occur due to the insufficient structural stability of the at least one screen element relative to the weight of the product being screened. Preferably, the support system includes one or more support elements that can be readily and easily installed and removed from the screen system. The support system is preferably configured to permit the one or more support elements to be positioned at different locations in the screen system. Preferably, the support system is configured to permit a variety of different support elements to be used to allow a greater variety of screen elements to be used.

Abstract: A vibratory separator including a frame, a basket disposed on the frame, and a motor configured to impart a vibratory motion to the basket. Additionally, the vibratory separator includes an adjustable speed drive operatively coupled to the motor to control a vibratory motion imparted to the basket. Also, a method of processing drilling waste including generating a first vibratory motion on a vibratory separator using at least one motor, and adjusting the first vibratory motion using an adjustable speed drive to generate a second vibratory motion.

Abstract: A molded polyurethane vibratory screen including a body having opposite side edge portions, upper and lower edge portions, an upper surface and a lower surface, first members extending between the side edge portions and the second members extending between the lower edge portion and the upper edge portion, third members substantially parallel and extending transversely between the side edge portions and having multiple first members therebetween, the fourth members substantially parallel and extending transversely between the lower edge portion and the upper edge portion and having multiple second members therebetween, reinforcement members molded integrally with the third and fourth members.

Abstract: A method of forming a shaker screen includes forming a frame, and attaching a first sealing element to at least one side of an outer perimeter of the frame, wherein the attaching comprises aligning a first mating surface of the frame to a second mating surface of the first sealing element, and wherein the first mating surface of the frame includes an extension, and the second mating surface of the first sealing element includes a groove configured to align with the extension. A system of sealing shaker screens includes a first screen and a second screen disposed adjacent the first screen, wherein a first sealing element of a first frame and a portion of the second screen interact to provide a seal between the first screen and the second screen.

Abstract: A shaker apparatus including a basket having an upstream side, a downstream side, and two side walls, at least one wedge guide and one support rail disposed on each side wall, and at least one screen assembly. The support rails and the wedge guides may be configured to engage the screen assembly. The screen assembly may have one or more layers of screen mesh mounted on a screen frame. The screen frame may include a first and a second side rail, each having an upstream end, a downstream end, a top surface, and a bottom surface. A slope of the top surfaces intermediate the upstream end and the downstream end may be different than a slope of the bottom surfaces intermediate the upstream end and the downstream end.

Abstract: A compact mobile variable angle vibrating screen with a suspension and dampening system configured to rapidly accommodate variable angles and exhibit acceptable vibration levels; especially during power up and power down surge vibration at the variable angles. The system comprises a group of bi-directional dual pivot leg vibration damper mechanisms, including nesting tubes, one with holes for receiving pins and the other with a semi-circular cutout at the bottom edge.

Abstract: Apparatus is provided, in or for a screen separator for sieving materials, for clamping one or more sieve screen frames 78 within the confines of a chassis 40 of the separator to prevent egress of material from the separator. The apparatus comprises a sheath 50 extending around and embracing the chassis 40 and one or more expandable elements 66 for urging the sheath 50 against the chassis 40 and the screen frame(s) 78 to impart uniform clamping pressure to the clamped elements. The sheath 50 is designed to provide ease of mounting and release.

Abstract: The invention concerns screen panels of the kind used in vibratory screening operations. According to the invention, the screen panels (10) include recycled polyurethane, typically that recovered from worn screen panels. In one particular embodiment in which the panel has an upper, perforated screening section (16.1) for performing a screening action and an operatively lower section (16.2) beneath the screening section, the upper section is of molded, virgin polyurethane and the lower section comprises a reinforcing frame (12) and recycled polyurethane molded about the reinforcing frame. The invention envisages the use of blends of virgin and recycled polyurethane as well as method of manufacturing screen panels and methods of handling worn screen panels.

Abstract: A vibratory plate screen having a first end for quickly mounting in a vibrator housing, an intermediate region with openings therein and a securement end that allows one to quickly secure a vibratory plate screen in a vibratory housing. In addition, the screen is sufficiently flexible to enable one to mount the vibrator screen in a curved condition or stressed condition so that the inherent tensile strength of the material assists in holding the vibratory plate screen in position. A further feature of the invention is the quick removal and securement of the vibratory plate screen.

Abstract: The present invention provides a screen system (8) suitable for use in a vibratory screen apparatus (1), and comprising: a screen element (11) and a support frame (12) therefor, as well as novel screen elements (11) and mesh panels (19) therefor, and the use thereof. The screen element (11) consists essentially of a mesh panel (19) provided with first and second elongate support members (22, 23) extending along opposite end portions of the mesh panel (19). The support frame (12) has spaced apart first and second elongate frame elements (13, 14) for engagement with the screen element support members (22, 23) and further elongate frame elements (17, 18) extending there between for supporting the mesh panel (19).

Abstract: A frame over which woven wire mesh is to be stretched and secured to form a sieving screen and which can be used to screen solids from drilling mud recovered from down-hole when drilling for oil or gas. The frame is a rectilinear moulded plastics frame having edge regions by which it is secured in place in a shaker. Within the frame is a plurality of rectilinear windows formed by an orthogonal array of intersecting ribs also of moulded plastics material. Some of the ribs are internally reinforced by rigid metal members which extend orthogonally between hollow box-section members which define a sub-frame for reinforcing the four edge regions of the frame. The orthogonal members are secured at their ends to the sub-frame. The ends of the sub-frame members are joined at the four corners of the sub-frame. In this way not are only the edge regions of the frame reinforced internally but so also are some of the orthogonally intersecting ribs, so as thereby to produce a rigid frame for the screen.

Abstract: A screening machine for screening bulk material and the like comprising a housing and two sidewalls at which a screen deck is disposed, the screen deck comprising cross-members mounted on the sidewalls and longitudinal members which are mounted on the cross-members and receive an exchangeable screen lining. Said longitudinal members are clamped to the cross-members by means of removable mounting ties from two different directions.

Abstract: A recycling cart (100) for sorting, retaining, and transferring articles is provided. The recycling cart includes a waste container (10), at least four supporting members (20), at least four rotating members (30), and a sorting member (50). The supporting members are attached with the waste container. The rotating members are attached with the supporting members and configured for facilitating moving the recycling cart. The sorting member is configured for sorting articles. The sorting member is hinged with two of at least four supporting members and located above the waste container.

Abstract: A vibratory separator (in one aspect, a shale shaker) and methods for using it, the separator in certain aspects having a base, a basket movably mounted on the base, screen apparatus on the basket, material flowing onto the screen apparatus for treatment, at least a portion of the screen apparatus not inclined downhill (e.g. said portion horizontal or uphill), electromagnetic vibratory apparatus connected to the basket for vibrating the basket and the screen apparatus, driving apparatus for driving the electromagnetic vibratory apparatus, and control apparatus (on-site and/or remote) for controlling the driving apparatus and the electromagnetic vibratory apparatus; the material, in one aspect, being drilling fluid material with solids therein.

Abstract: A planting board system is provided for use in performing germination testing or planting within the flat of a seed type. The planting board system includes a housing, a lower panel disposed in the housing, said lower panel having a plurality of apertures disposed within the lower panel in a predetermined, spaced apart relationship and an upper panel disposed within the housing, the upper panel at least partially overlapping the lower panel and being moveable within the housing relative to the lower panel between first and second positions.

Abstract: A screen apparatus, which in certain aspects is a screen apparatus having a support, screening material on the support, and energizable identification apparatus on (exteriorly, interiorly, and/or within) the support for identifying the screen apparatus; a vibratory separator with such a screen apparatus; and a vibratory separator or shaker with energizable identification apparatus.

Abstract: A screening machine includes a vibratory carrier and a vibratory drive operatively coupled to the vibratory carrier for imparting vibratory motion thereto. The screening machine includes a screen assembly selectively coupled to the vibratory carrier so that the vibratory motion is transmitted to the screen assembly. A sealing mechanism including at least one rotary cam having a cam surface and at least one actuator being accessible to a user of said screening machine is coupled to the rotary cam. Actuation of the actuator to rotate the cam urges the screen assembly and the carrier into sealing engagement with a confronting surface of the screening machine. The screening machine further includes at least one stop positioned relative to the sealing mechanism to limit rotational movement of the rotary cam in at least one direction.

Abstract: An apparatus and method for separating material are described. A material separator may include a frame. At least a portion of the frame may be filled with a vibration dampening material.

Abstract: An apparatus and method for separating material are described. A material separator may comprise a frame. The frame may comprise a base supporting a slanted grate deck. The base may comprise a front wall and two opposing side walls and a suspended deck support positioned below and separated a predetermined distance from the slanted grate deck by at least one deck brace.

Abstract: An apparatus and method for separating material are described. A material separator may comprise a frame. The frame may comprise a base supporting a slanted grate deck. The base may comprise a front wall and two opposing side walls and at least one seating member coupled to and extending upwardly from a top portion of the front wall.

Abstract: A multi-screener apparatus in which the height of the apparatus may be adjusted for the convenience of a user. This multi-screener apparatus prevents the unwanted movement of the apparatus frame without the addition of counterweights or excessive frame mass to prevent the unwanted movement. Also, this multi-screener design may function with a variety of power sources, including electrical and fossil fuel based power sources. The unit is easily placed in a desired location by optional vehicle attachment means for towing as well as gripping handles and wheels for manually positioning the apparatus in a desired location. Further, the lightweight design of the apparatus also plays an important role regarding the mobility of the apparatus.

Abstract: A vibratory separator having a basket for supporting screen apparatus for treating material, the basket pivotably mounted on a base, vibratory apparatus connected to the basket for vibrating the basket, the material forming a pool on the screen apparatus, and a beach formed on the screen apparatus, measurement apparatus connected to the basket and positioned above the screen apparatus for measuring a distance from the measurement apparatus to a top surface of the pool, control apparatus for controlling and in communication with the measurement apparatus for receiving signals therefrom indicative of said distance, which distance is indicative of pool depth at that location and which correspond to beach extent, and adjustment apparatus controlled by the control apparatus for adjusting angle of the basket, thereby adjusting extent of the beach.

Abstract: The invention provides a screen which has a screen body (12) and a plurality of ribs which extend across the screen body. Screening apertures (118) are defined in the screen body by the ribs. A reinforcing frame (124) is embedded in the screen body, which frame is made of a first plastics material which has a greater density than a second plastics material from which the screen body (12) is made. The frame has keying formations formed therein to assist in bonding between the frame and the screen body.

Abstract: A vibratory separator having a base, a basket movably mounted on the base and for supporting screen apparatus for treating material introduced into the vibratory separator, the basket on a base and pivotable with respect thereto, vibratory apparatus connected to the basket for vibrating the basket, screen apparatus supported by the basket, the material flowing onto the screen apparatus for treatment, angle adjustment apparatus connected to the basket for adjusting angle of the basket, sensor apparatus for sensing a parameter indicative of basket angle and for providing a signal corresponding to said basket angle, control apparatus for receiving signals from the sensor apparatus and for controlling basket angle based on said signals, the angle adjustment apparatus, in one particular aspect, including a rocker arm assembly with a first pivotable end.

Abstract: A filter screen for a shale shaker includes a first end, a second end disposed opposite the first end, a first side disposed substantially perpendicular the first and second ends, a second side disposed opposite the first side and a plurality of transverse ribs disposed between the first side and the second side, wherein at least one transverse rib extends downwardly below a lower plane of the screen frame. A filter screen for a shale shaker includes a first end, a second end disposed opposite the first end, a first side disposed substantially perpendicular the first and second ends, a second side disposed opposite the first side, a plurality of transverse ribs disposed between the first side and the second side, and at least one positioning tab. A method of forming a screen frame for a shale shaker includes forming a screen frame and forming integrally a gasket along a perimeter of a lower plane of the screen frame.

Abstract: An attrition mill for reclaiming foundry sand from deposited material having lumps of used foundry sand and included material includes a housing defining a chamber for receiving the lumps of used foundry sand and included material. A base is disposed within the housing and has an elevated end defining a reject outlet adjacent a reject end of the mill and a lower end, and a discharge wall is positioned adjacent the base lower end to define a sand outlet adjacent a sand end of the mill. A resilient support is attached to the housing, and a vibratory drive is attached to the housing and includes first and second eccentrically loaded motors.

Abstract: A vibratory screening machine having opposite sides with a plurality of stationary aligned tensioning members mounted on one side and a plurality of nut actuated movable tensioning members mounted on the opposite side and a vibratory screening screen mounted on the stationary and movable tensioning members. The tensioning members have upstanding fingers which are received in apertures in the plates of the vibratory screen, and the edge portions of the vibratory screen include screening material which extends all of the way to the extreme edges of the supporting plate and the fingers are below the screening material. Also, the tensioning structure is mounted on the side walls of the vibratory screening machine below the vibratory screen.

Abstract: A vibratory separator having a basket with a first side spaced-apart from a second side, screen assembly apparatus mounted in the basket, the screen assembly apparatus having a central portion, a first screen side and a second screen side, central support apparatus connected to the basket and positioned beneath and in contact with the central portion of the screen assembly apparatus, and pressing apparatus on the first side and second side of the basket for pressing down on the first screen side and on the second screen side of the screen assembly apparatus so that the central portion of the screen assembly apparatus is higher than the first screen side and the second screen side.

Abstract: A hybrid incline/horizontal screen for separating particulate material into predetermined size fractions, the screen having multiple screen decks mounted on a frame, at least one uppermost screen deck having an inclined receiving end and a horizontal discharge end. Each screen deck has a screening medium with predetermined sized openings that screens the particulate material. The screen decks are in stacked relationship, the upper screen deck having the largest screen medium openings, the openings becoming progressively smaller the lower the screen deck is mounted on the frame. The inclined receiving portion of the one or more uppermost screen decks provides for rapid material separation and conveyance through the upper screen decks to the lower screen decks while the horizontal discharge end reduces the tendency for the material to pile up (snowball) and maintaining a more uniform material bed, while providing for a shorter, more transportable screen.

Abstract: A screen assembly 22 includes a conveyor 26 pivotably mounted beneath a screen 24 for segregation of fractions of material, for example from a mobile crusher 10. Hydraulic cylinders (not shown) are used to selectively move telescopic arms 48 (only one of which is shown in the Figures), to raise or lower the conveyor 26 between operative position and inoperative positions. In the operative position the conveyor 26 is substantially parallel to the screen 24 for receiving material which has passed through the screen mesh, in use. In the inoperative position the conveyor 26 is angularly displaced relative to the screen 24 about the pivot, to provide access to the underside of the screen 24, e.g. for maintenance purposes. Removable pins 50 are provided for releasably securing the attitude of the conveyor 26 relative to the screen 24 in the operative position.

Abstract: A method of plugging an area of damaged mesh in a sifting screen. The method is applicable to screens in which woven wire mesh is stretched, tensioned and secured over a supporting frame containing a plurality of windows and in which local damage to the mesh is in an area of the mesh which overlies one of the windows. The method has the steps of inserting into the window a device which is a close fit therein, and securing the device in the window so as to completely cover the area of damaged mesh. The device may be a former having stretched thereacross and secured thereto mesh similar to that stretched across the window in question, or simply a plate or block. The device may be secured in place by a force or interference fit, mechanical means, or adhesive, or the device may be resiliently deformable to allow it to be pushed past a projection in the window, so as to snap fit the device in place.

Abstract: There is provided screen apparatus comprising side walls having a lower edge portion configured to accept tubular screen support members. An upper edge extends from the inlet end of the side walls to an apex from which a declining edge extends to the foot of the side walls. The lower edge, upper edge and declining edge are each provided with edge stiffening. A torque tube is secured between the respective exciter mount castings, the torque tube and stiffened side wall being selected to provide that the first fundamental frequency mode greater than the exciter frequency is at least 2 Hz greater than the exciter frequency and the first fundamental frequency below the exciter frequency is at least 2 Hz lower than the exciter frequency.

Abstract: A separator for use in separating larger rocks from smaller rocks and soil in which the upper rear support includes a connecting member allowing the sizing members to be adjusted to reject different minimum sizes, and in which the connecting member is recessed to protect it from damage during transport.

Abstract: A panel for screening material, comprising: a frame defining a screening area; a tensioned fiber reinforcement attached to the frame and spanning across the screening area; and a non-tensioned resilient coating surrounding the fiber reinforcement so as to form a plurality of openings to screen the material. A method of making a screen for screening material and a vibratory screening machine apparatus incorporating such a screen panel are also disclosed.

Abstract: A vibratory screen separator using screens includes a base and a housing resiliently mounted to the base and divided into two wall portions held together by a clamp band. Brackets are located high on the housing and lifts are diametrically positioned to either side of the housing. The lifts are pivotally mounted to the base through feet to move from a first position engaging the brackets to a second position displaced from the housing. Each lift includes a fluid cylinder and shaft mounted to an arm. A head associated with the shaft of the fluid cylinder and shaft engages a slot on the associated bracket and can operate to lift a portion of the housing with the clamp band removed. In this lifted state, access is provided to screens clamped within the housing between housing portions.

Abstract: A vibratory screening machine having opposite sides with a plurality of stationary aligned tensioning members mounted on one side and a plurality of nut actuated movable tensioning members mounted on the opposite side and a vibratory screening screen mounted on the stationary and movable tensioning members. The tensioning members have upstanding fingers which are received in apertures in the plates of the vibratory screen, and the edge portions of the vibratory screen include screening material which extends all of the way to the extreme edges of the supporting plate and the fingers are below the screening material. Also, the tensioning structure is mounted on the side walls of the vibratory screening machine below the vibratory screen.

Abstract: The invention provides a method for exchanging a plurality of sifter frames of a plan sifter. The steps of the method include a step, when taking out a number of sifter frames from a sifting chamber, of taking out a plurality of sifter frames in a unitary state with the unitary state being maintained to the outside of the machine frame, and a step, when accommodating new sifter frames in the sifting chamber, of stacking the sifter frames outside the machine frame and accommodating the unitary formed sifter frames in the sifting chamber. According to the method of the invention, the sifter frame exchange operation can be carried out in such a way as to reduce heavy labor and risk to workers, and such exchanging operation can be carried out in an easy manner.

Abstract: A tension fastener includes a quick release feature. In one embodiment, the fastener has a moveable feature that can be used to maintain a compression force on a coil spring of the fastener. In one embodiment, the moveable feature is a pair of arms attached to the quick release head. The fastener can be used in a manufacturing environment having sifting tables to attach a sifting screen to a frame of the sifting table.

Abstract: A continuous-belt drilling mud separation unit is removably mounted in a box-like housing disposed in the flow path of drilling mud or drilling fluids and is operated by a motor on the housing. The separation unit includes a generally rectangular frame, a tensioning system, and a wide continuous belt in the form of a mesh screen, chain, self-cleaning chain link belt, or combination chain link belt and wire mesh screen which extends around rollers or sprockets and is driven in a continuous loop moving along the longitudinal axis of the frame. As drilling mud or drilling fluids are conducted onto the moving belt, liquids and particles smaller than the openings in the belt pass through the openings and liquids and particles larger than the openings are transported on the moving belt and are discharged off of one end as the belt completes its path.

Abstract: The invention relates to a sieve frame for plan sifters and also to a method of producing it. It is used mainly in plan sifters for milling. The object is to improve the functionality of an insertable sieve frame and to simplify production.

Abstract: A screen frame and screen are secured into sealing engagement within a screening machine by a screen frame sealing mechanism and method which allows the user to simultaneously raise an entire side of the screen frame into sealing engagement. Advantageously, the entire screen frame can be raised into sealing engagement to prevent the escape of fine material being screened and avoid metal-to-metal contact during the screening process from a single location.

Abstract: An apparatus for screening particulate material having a base frame (11), an elevating conveyor (12), and a conveyor carrying frame (13) adjustably mounted on the base frame (11) and arranged to be capable of moving the conveyor (12) generally lengthwise to adjust the position of an upper end (16) of the end (16) of the conveyor. A sub-frame (18) is pivotally adjustably mounted on the base frame (11) via a pivot (20), and it carries a vibratory screen (17) arranged to receive material falling under gravity from the upper discharge end (16) of the conveyor (12). The sub-frame is adjustable about the pivot in order to adjust the attitude of the screen. A tail conveyor (23) is provided for discharging separate screened portions of the material. A linkage (19, 22) exists between the sub-frame (18) and the carrying frame (13) which includes a direct pivotal connection (20) between the sub-frame and the carrying frame whereby there is simultaneous lengthwise adjustment of the sub-frame.

Abstract: A screen basket for filtering an aqueous fiber suspension includes a cylindrical foraminous filter element, anchoring collars surrounding and fixed to opposite ends of the filter element, at least two support rings surrounding the filter element, and support rods for adjusting the support rings between axially contracted positions disengaged from the anchoring collars, and axially expanded positions engaging the anchoring collars and axially tensioning the filter element. In a first embodiment, the anchoring collars are relatively flexible. This allows the anchoring collars to be deformed for insertion of the cylindrical foraminous filter element within the support rings. Alternatively, the upper and lower support rings are divided into segments that are easily disassembled and reassembled to facilitate removal of a defective cylindrical foraminous filter element and installation of a new filter element.

Abstract: A multi-functional linear motion shaker includes a rectangular outer support frame with a tank, often referred to as a "possum belly", for receiving the incoming drilling fluid flow. A set of adjustable louvers and a tray is positioned on the side of the tank. The adjustable louvers and tray serve to screen out the larger and stickier drill cuttings or solids. A vibrating deck assembly is positioned within the outer support frame adjacent the tank and tray assembly. The vibrating deck assembly is of a double deck design whose upper and lower decks include cross members to support the mud screens. The upper and lower decks are vertically spaced apart and connected together into one unit by vertical structural members. A moveable plate is positioned on the upper deck adjacent the adjustable louvers and tray. This moveable plate can be positioned to direct drilling fluid flow to the upper deck or repositioned to redirect fluid flow to the lower deck and bypass the upper deck.

Abstract: A separating apparatus is disclosed for separating debris from materials. The apparatus includes a container which defines an opening for the flow therethrough of the materials. A frame is disposed adjacent to the opening. The frame has a first side which is pivotally connected to the container about a pivotal axis. A second side of the frame is disposed remote from the first side. A separating device is pivotally secured to the frame about a further pivotal axis. The separating device extends across the opening between the first and second side of the frame when in a first disposition thereof. An actuator co-operates with the separating device for permitting movement of the separating device to a second disposition thereof away from the frame and the opening.