Abstract: An improved filter apparatus (10) for removing debris from a free flowing water system (100) is described. The apparatus includes a rail (12) which is mounted adjacent the water supply intake opening (102) and a continuous belt (36) made of chain links (38) and connectors (44) which mounts around an upper sprocket cylinder (26) and a lower sprocket cylinder (32) spaced between the ends of the rail. Openings (42) in the belt collect debris from the water flowing through the belt. The connectors have lifters (50) which move the debris collected on the front side (36A) of the belt and are able to tilt to dump any debris of excess weight back into the water system. The belt is moved upward by a motor (54) which rotates the upper sprocket cylinder. As the belt moves upward, the debris collected on the belt and by the lifters is moved out of the water system toward the top of the rail.

Abstract: A screw conveyor including a feed screw formed, at least partially, as a shankless screw, a jacket surrounding the feed screw and a brush cooperating with the inner surface of the jacket for cleaning the same, with the feed screw including a plurality of substantially band-shaped screw threads extending along an imaginary helical line and arranged, when viewed in a transporting direction, one behind the other with an ever increasing distance from a screw axis so that each two adjacent screw threads form a step therebetween, and with the brush being arranged on the step formed by two outmost screw threads.

Abstract: A laterally moveable bar rake is provided for cleaning a bar rack installed across a water stream of a water treatment facility, storm water station or the like. The device includes a traveling framework for back and forth movement across the top of the bar rack, a telescoping arm with a rake head mounted on the lower end of the telescoping arm and a tilt mechanism for tilting the telescoping arm between raking and extension position so that the arm can be extended to the bottom of the bar rack or beyond, tilted toward the bar rack and withdrawn along the bar rack to rake debris onto a discharge hopper or conveyor.

Abstract: A bar screen for screening a flow of wastewater, the bar screen comprising a frame, a first bar rack supported by the frame and extending across the flow of wastewater, the first bar rack including a plurality of generally parallel, elongated first bars each having a top end and a bottom end, the plurality of first bars defining therebetween a plurality of upstream spaces, a first bar rack top support engaged with the top end of each first bar and a first bar rack bottom support engaged with the bottom end of each first bar, a second bar rack supported by the frame and extending across the flow of wastewater, the second bar rack including a plurality of generally parallel, elongated second bars each having a top end and a bottom end, a second bar rack top support engaged with the top end of each second bar and a second bar rack bottom support engaged with the bottom end of each second bar, the second bar rack bottom support overlying a portion of the first bar rack bottom support, and a mounting arrangement f

Abstract: A sewage water installation has a discharge basin in which is arranged a screening unit linked to a back-and-forth movable cleaning carriage. The discharge basin (20) is subdivided by a partition (24) and by the screening unit (30) into a storage chamber (25') and an outflow chamber (25"). The storage chamber (25') is linked to an inflow pipe (26) and to an outflow pipe (27) and the outflow chamber (25") is linked to an outflow pipe (28). In order to increase the storage volume and to reduce the throughflow speed, a retaining element (40) is arranged on the back-side of the screening unit (30), as seen in the direction of flow, inclined so as to form an angle therewith.

Abstract: A submersible motor enclosure and method of operating the same, having particular utility for enclosing a motor used to power a screen rake in a waste water treatment plant. The enclosure has a closed end and an open end coverable by a cover plate. A pressure source is in communication with the housing interior to pressurize the interior and to resist the migration of water into the housing. A discharge port may be included to collect and discharge any water that enters or condenses in the housing. An alternate embodiment utilizes a vacuum source in communication with the discharge port instead of the pressure source in communication with the housing interior.

Abstract: Apparatus for scraping debris from a trash rack occupying a position in a owing stream has a driven, upper turning drum and a pair of chains trained about the drum and carrying scraper blades which engage and carry debris on the upstream side of the rack upwardly for disposal. Each chain is composed of a plurality of links joined at their ends by pivot connections which limit the pivotal movement of the links from positions of linear prolongation in such manner as to avoid the necessity of a lower turning drum. By supporting the chain from an upper drum only, the lower parts of the chain are movable freely in directions away from and toward the rack, as well as vertically.

Abstract: A water intake comprises a common frame and assembled thereto and-forming therewith an integral self-contained unit a pump adapted to be immersed and a trash rake and an associated grid on the suction side of the pump and/or a filter on the discharge side of the pump.

Abstract: An apparatus for separating solids from liquids including an endless rotatably mounted band of collecting arms for collecting screened solid material, each of the collecting arms having a leading collecting face and two opposite sides adjacent the leading collecting face, and being mounted on support rods which are arranged in spaced relationship around the band, link pieces rigidly attached to the collecting arms for linking one support rod to the next, such that the link pieces form continuous chains around the band, and separate the collecting arms one from the other to form slots between the link pieces, said link pieces being rotatable on the support rods to which they are attached, and a rotatable set of discharging teeth arranged to cooperate with said movable band by entering the slots as the band rotates to move along the leading collecting faces of the collecting arms, thereby to remove collected material gathered at the slots and from said leading collecting faces of the collecting arms.

Abstract: A long sand trap for separating and removing sand from inflow channels, particularly of sewage treatment plants is provided with a settling channel (1) having in particular a trapezoidal cross-section and extending along a straight path. A transporting conveyor device (8) which is acting opposite to the direction of flow is provided in the bottom area (6). A classifying conveyor device (10) discharges the sand delivered from the transporting conveyor device (8) in an upwardly inclined manner. The classifying conveyor device (10) is arranged in the central longitudinal plane (3) of the settling channel (1). It has a discharge chute (17) which can be used selectively left-hand or right-hand.

Abstract: The filter arrangement is provided with a filter in the form of an endless conveyor which is releasably mounted within a transport chute through which a flow of water can be directed. The filter is formed as a unit to be released from supports at the bottom of the transport chute for ease of cleaning. The filter is further pivotally mounted at the lower end so as to be adjusted angularly relative to the flow of water through the transport chute. Seals are provided between the sides of the filter and the side walls of the transport chute to preclude passage of liquid. A plurality of such filters may be disposed within the transport chute and may be associated with various discharge conveyors for discharging materials which have been filtered out of the flow of liquid.

Abstract: Apparatus for separating solids and liquids has an initial separator for removing coarse solid material from a mixture of solids and liquids, a first screen for separating further solid material from the liquid and a first auger extending axially through the first cylindrical screen for removing the separated further solid material from the first cylindrical screen. A second screen receives the liquid from the first screen and separates fine particles from the liquid, and a compactor between the first and second screens compacts the solid material removed from the first screen by the first auger. A second auger is provided in the second screen for mixing and removing the compacted solid material and the separated fine particles.

Abstract: Apparatus for protecting from water damage the electric motor which drives the cog rake bar screen of a waste water treatment plant. A shell of air impermeable material surrounds the motor and has an opening at the shell bottom to drain water. Various arrangements and devices prevent water or debris from entering the opening.

Abstract: One has aimed at providing a simple, reliable and efficient purification device for the mechanical purification of sewage. At this end, the sewage purification device (1) comprises substantially a strainer pipe (2), which may be designed to be coupled to a sewage pipe (P1), and which is perforated in that portion thereof which, in the position of use, constitutes the bottom portion. The strainer pipe (2) is assigned a water collecting pipe (4) underlying the former in the position of use, extending parallely thereto and, preferably, being sealingly connected thereto, said water collecting pipe (4) being adapted to receive mechanically purified sewage from the strainer pipe (2). The water collecting pipe (4) is open or, respectively, provided with holes, perforations or slots in the portion thereof being opposite to the strainer pipe (2).

Abstract: An apparatus conveys screenings collected on a bar screen partially immersed in a sewage flow and inclined in the flow direction, and in certain cases on an adjoining apron screen. A rake device conducts the screenings to a discharge position at the upper edge of the bar screen or the apron screen. The screenings are conveyed simultaneously along at least two conveying paths and thus given screenings are transferred along mutually adjoining conveying paths. The rake device includes at least two rake members spaced at intervals in the conveying direction and connected together by a common drive that causes simultaneous translatory movements in the same direction of both rake members.

Abstract: A mechanically cleaned bar screen or bar rack is disclosed for removing debris from water and wastewater treatment facilities which comprises a frame with housings supported thereon and a bar rack and dead plate. The apparatus is supported on the ledge of the sluice of a water or wastewater treatment facility tilted backward at an angle of about 0.degree.-30.degree. with the bar rack submerged in the flowing stream of water. A carriage carries a pivotally mounted rake assembly with a rake engaging the bar rack. The carriage is reciprocated along a guide rail by motor operated lead screws which extend through rollnut assemblies supporting the carriage. At the top of the traverse of the carriage, the rake is swept by a wiper to remove debris to discharge down a chute for pick up. The motorized drive system is totally enclosed. The motor and gear boxes are stationary and do not travel with the rake carriage. Corrosion resistant materials are used to ensure long life.

Abstract: A rotary screening device for separating unwanted solid matter such as sewage, weeds, tar globules and fish from water which is to be used for special purposes such as water cooling or other plant processes. The device comprises a rotating hollow stack of closely spaced coaxially mounted annular discs, each of which is provided with peripheral teeth upon which unwanted solid matter may be caught and carried away to a collection zone and by scraper elements engaging annular tracking surfaces between the teeth on adjacent discs. The tracking surfaces have apertures or slits to permit passage of cleaned water to the interior of the hollow stack to which may be connected stationary ducting means for conveying the cleaned water therefrom.

Abstract: Apparatus for separating liquids and solids, comprising, separator screen means for receiving and separating the solids and liquids, conveyor means for feeding the separated solids upwardly from the separator screen means, and compactor means for compacting the solids, the conveyor means comprising a first conveyor extending at a first upward inclination through the separator screen means and a second conveyor extending further upwardly and at a greater inclination than the first conveyor means.

Abstract: An apparatus is described which separates small solids from process waste water. A continuously rotating elongated drum screen having a large diameter interior flow channel removes the solids. The drum screen contains a continuous loop of closely spaced link members each having a foot at one end projecting towards the interior of the drum chambr. Pivot members are connected to the links and these pivot members are driven by lugs attached to an endless loop chain. The chain is driven by variable speed motors. A flushing system mounted on top of the drum screen washes solids into a hopper where liquid is returned to the drum inner chamber and solids are sent to solid waste disposal.

Abstract: A machine for intercepting solid constitutents in a liquid stream, such as sewage, has a frame which carries a downwardly sloping screen positionable in and across the stream so that the liquid flows through but the outer side of the upwardly and forwardly sloping screen intercepts solid constituents. The screen has a stationary grate with parallel grate bars extending from the lower to the upper end of the screen, and a mobile grate with parallel grate bars which alternate with the grate bars of the stationary grate. The mobile grate is repeatedly movable forwardly of the stationary grate to lift off the stationary grate bars those solid constitutents which were intercepted by the two sets of grate bars, and the mobile grate is then moved upwardly to raise the lifted solid constituents along the outer side of the stationary grate prior to redepositing the lifted constituents on the stationary grate.

Abstract: Improved bar screen raking systems are provided with telescopical boom members, forming the rake arm controlling displacement up and down, in combination with a hydraulic piston rod cylinder, controlling displacement in and out. In one embodiment the raking system includes a telescopical rake arm boom comprising a boom member supporting a bearing slide and ball carrier, a cam follower and track arrangement in fixed spaced apart parallel disposition on opposing sides along the length of said boom, a boom side member connected to said bearing and cam arrangements for carrying a rake, a hydraulic piston driven cable device fixedly supported by said boom and parallel to said bearing slide and cam follower arrangements for controlling boom displacement up and down and a hydraulic piston rod cylinder device for controlling boom displacement in and out.

Abstract: A bar screen assembly includes a bar rack interposed across a passageway. At least one rake arm for raking debris from the bar rack to an upper end of the bar rack is provided. An apron adjacent the upper end of the bar rack receives debris, and the apron is mounted to the frame for movement between a receiving position and a dumping position. A mechanism is provided to sense movement of the rake arm relative the upper end of the bar rack, and a mechanism is provided for moving the apron from the receiving position to the dumping position in response to the sensing mechanism.

Abstract: An apparatus for removing solids from a liquid flow stream comprising a bar screen for obstructing solids from the liquid flow stream and a reciprocal rake having a plurality of projection adapted for cooperation with the bars of the screen for removing solids accumulated thereon. The opposite sides of the rake are supported by guide rollers adapted for maintaining the rake projections in pre-determined relatively closely spaced relation to the bars during an upward raking stroke for effecting substantially complete removal of solids accumulated on the bars while preventing continued direct contact between the rake projections and the bars.

Abstract: A device for the separation and transport of material from polluted medium, for example waste water, comprises a grate (5) mounted in a support structure (1). The grate is composed of a series of stable rods (3) and adjustable rods (4), where the stable and adjustable rods are respectively joined and form a unit. Said unit is disposed in the grate (5). The grate (5) is provided with or without three wave-shaped shelves (6, 7, 8). One shelf (6) is disposed at the bottom of the device just below the surface of the medium, and the other two shelves (7, 8) are disposed at the top of the device, with the shelf (7) being mounted at about the surface of the medium. The edges of the rods (3, 4) having the shelves are turned against the direction of flow of the medium. The adjustable rod unit (4) is disposed so as to be driven up and down by a piston (8'). The piston (8') is suspended on a rail (10) mounted in the support structure (1). The movement proper is being performed by a wheel (15).

Abstract: The invention relates to a separating conveyor for separating solid materials from liquids. According to the invention, above the conveying path (17) of the conveyor and essentially supported against the conveying path (17) there is arranged a grate (1) which at least at one end is connected to the conveyor by means of elastic members (2). In addition to this, the conveying path (17) is provided with members (6) in order to guide the grate and the solid materials.

Abstract: A method and device for the separation of substantially solid bodies from a liquid are disclosed in which an obliquely arranged screen grid is provided with an upper region, a lower region, and two opposite edge regions and is suppllied with liquid at the upper region to separate the solid bodies from the liquid in the form of screenings which travel along an upwards facing surface of the screen grid. A cleaning device rests against the upwards facing surface of the screen grid and moves the screenings during movement of the cleaning device horizontally towards the edge regions to cause the screenings to pass onto transport surfaces situated adjacent to the edge regions. The transport surface extends along the length of the screen grid and is smooth.

Abstract: A fish protection system for dams comprises a series of modular units which interconnect by male and female fittings on each side of the modular unit. Each modular unit comprises a casing, an inner box and an outer box for anchoring the unit to a stream bed and side frames. A screen and cleaning mechanism can be placed within the modular units where the screens clean and direct debris and fish to a fish ladder. A cleaning comb or cutting bar moves around the modular unit such that it keeps the screens clean and directs the debris and fish to the fish ladders. The cleaning comb by use of its rounded tooth form, minimizes flow at the screen in order that fingerlings won't be harmed by the cutting edge. A fish ladder provides a constant flow by maintaining the same depth of water by a hinged ladder.

Abstract: A lift apparatus adapted for reliable, substantially maintenance-free operation in material transfer systems, including systems that are subject to considerable contamination. The lift apparatus includes an open top container, a support plate for normally supporting the container in upright position, and a ball screw drive for moving the support plate and container between a filling station in which material may be introduced into the container and a discharge station. The container is supported for relative pivotal movement with respect to the support plate, and a chain and sprocket arrangement is provided for automatically pivoting the container to a dumping position as it is raised into the discharge station and for returning the container to its normal upright position as it is lowered from the discharge station following dumping.

Abstract: Bar screen apparatus of the type having a motorized rake assembly, that mounts an electric drive motor with associated electrical components which moves the assembly along a guide frame in a closed, approximately vertical path from an upper parking position to and through a lower reversing direction position, is imporved by adding a protection device to prevent the drive motor and associated electrical components from being submerged in a stream of sewage passing the apparatus at an abnormally high level.

Abstract: A bar screen cleaning apparatus in which a rake for cleaning the bar screen is raised and lowered by a transport system which includes an elongated flexible motor-driven train which transports the rake, a train track which extends substantially parallel to the bar screen at its lower end and curves at its upper end over the platform and a curved guide to maintain the train in engagement with the track and to guide the flexible train along the path of the curved track.

Abstract: A device for removing waste material screened or filtered out of liquid flowing through a channel (1) has a basket-type interceptor (6) that is slanted and cylindrical and that rotates subject to power, extends to some extent into the liquid, and has its upstream face (8) open and its downstream face (9) solid. A conveyor (13) is positioned coaxially in relation to the interceptor, leads to a waste-material deposit point outside the liquid, accommodates a powered conveyor screw (18), and has an intake scoop (15) in the vicinity of the interceptor for collecting the waste material. A mechanism positioned stationary above the intake scoop releases waste material from the interceptor. The interceptor consists of a number of continuous annular disks (8) distributed along the outer surface with gaps between them and the waste-material releasing mechanism is a raker-stripper (28) that at least to some extent extends through the gaps between the annular disks.

Abstract: A bar screen filter comprises a plurality of bars arranged in closely spaced parallel relation so as to define slots through which liquid flows. A scraper element is disposed above the bar screen and has a plurality of free floating knife blades projecting downwardly through the slots between the said bars.

Abstract: An apparatus is described which separates small solids from process waste water. A continuously rotating elongated drum screen in a three foot diameter flow channel removes the solids. The solids are deposited by spray wash into a dewatering chamber. The screen components include row of closely spaced links and pivot members connected end-to-end to form a continuous loop mounted within a frame driven by a variable speed motor.

Abstract: A bar screening apparatus for the efficient screening and removal of solid materials from a liquid flow stream. The bar screen includes a plurality of bars that are disposed in substantially parallel adjacent relation to each other and each have an upstream face disposed at an acute angle to the direction of flow of the liquid flow stream for enhancing screening of even relatively thin solid waste materials without significantly impeding the flow stream. The bars of the screen preferably are formed with a plurality of flow apertures in their active region which further minimizes head losses in the system and enhances screening of solid materials. A power operated two-directional rake is provided for more efficiently removing solid material that accumulate on the bar screen. Projections on the rake engage the bar screen only in one direction of the rake's movement and means are provided for forcing a close-fitting relationship between the rake projections and the screen bars during the raking operation.

Abstract: A bar screen cleaner utilizes a reciprocal carriage mounted downstream of a vertical bar screen to move a cleaning rake vertically to clean accumulation from the screen. The cleaning rake is pivotally mounted to the carriage such that the rake is positively urged into engagement with the bar screen as the carriage reaches its lowermost position. The rake is latched in a screen engaging position during the upstroke of the carriage and is released as the carriage reaches its uppermost position.

Abstract: The present invention relates to a raking apparatus which has at least an upper section and a rake section rotatably coupled to the upper section for rotatable movement from a first position spaced from the bar screen to a second position for removing debris from the bar screen. The rake section moves from the first position to the second position under the influence of a counterweight or other biasing force. A shock absorber placed between the rake section and the upper section controls the forward motion of the rake section to prevent damage to the rake apparatus from uncontrolled forward movement of the rake section from the first position to the second position.

Abstract: A rake apparatus for use with a bar screen in a fluid channel that catches debris whereby the rake apparatus enters the channel with reciprocal movement to remove debris caught on the screen bars. The novel raking apparatus has the ability to encounter an obstruction in the bottom of the channel and remove all or part of the obstruction during each cycle of operation without damage to the raking structure. This is accomplished by forming the raking apparatus of an upper section, a midsection and a lower rake section wherein the midsection is rotatably attached to the upper section and weighted to provide a force on the midsection and its attached rake section in the direction of the bar screen. The rake section is pivotally attached to the midsection to allow the rake section to pivot backwards with respect to the midsection if it strikes an obstruction while allowing the midsection to continue its forward motion thereby protecting the apparatus from damage.

Abstract: In order to clean a screen in a waste water purification plant a surge of a body of water is generated by the agency of a dump flushing apparatus, which surge drops in a free fall towards the screen to be cleaned. This surge of cleaning water is given a dimensional extent which ensures for a substantially simultaneous impinging of the body of water onto the total extent of the screen. A framing which surrounds the screen encompasses this surge of water such as to guide the water and to force the water to flow through the screen. During the cleaning or flushing action the contaminants adhering to the screen, which contaminants are substantially of a thixotropic nature, will be removed from the screen and flushed through a sump towards the water purification section of the water purification plant.

Abstract: A self-relieving bar screen, for intercepting debris moved by a liquid through a conduit into a space having a greater lateral dimension, includes a series of bars disposed in spaced lateral relation in a position normally opposite the discharge end of the conduit, with a lower, generally forwardly extending portion of each bar below the lower edge of the conduit and a generally upwardly portion extending up to opposite the upper edge of the conduit. The series of bars extend laterally past each side of the conduit but for a distance less than the width of the wall at which the conduit terminates. The side spaces thus provided permit liquid to flow to each side of the bars, in the event debris accumulates on the bars and may otherwise tend to obstruct the flow of liquid. The bar screen may be moved upwardly periodically with the debris collected thereby and emptied into a receptacle or the like, through a pivotal rake which is specially positioned.

Abstract: A bar screen/conveyor system for collecting debris or the like in a stream of liquid, including collector rakes for attachment to the conveyor which are made of a tough, abrasion-resistant and corrosion-resistant elastomer is described. The preferred elastomers for use in rake fabrication are polyurethane elastomers. The conveyor systems which include the elastomeric rakes have greater durability and use life without problems than the heretofore conveyor systems utilizing metal rakes.

Abstract: An industrial water intake comprising a screen for screening water and a spray nozzle for detaching deposited debris from the screen and entraining it into a debris recovery channel on the other side of the screen from the spray nozzle. A cylindrical rotary member comprising a roller is arranged along the adjacent longitudinal edge of the debris recover channel. The rotary member rotates in a direction tending to carry debris falling on or coming in contact with the longitudinal edge into the channel to prevent the build up of debris thereon. The rotary member extends above and is disposed inwardly of the longitudinal edge relative to the debris recovery channel. The rotary member is usable on recovery channels for band screens, drum screens or even bar screens associated with trash rakes.

Abstract: An improved filter lift system including generally vertical filtering member with a plurality of generally vertical elements or rearward sloping elements, bars or strips of material positioned across a fluid stream, and teeth lift mechanism with teeth positioned between the filtering elements for lifting debris positioned forward, adjacent and upstream to the filter lift system. The debris removal means includes the teeth that lift and dump the debris and claws that clean and pull debris off the teeth. In phase one, the teeth lifting mechansim moves the teeth upward through a rearward sloping lower portion of the face of the filtering element to prevent compacting of debris below the teeth. The teeth lifting mechanism moves the teeth upward. In a second phase, the distal upstream portion of the teeth project out from between the filtering elements on the upstream side to pick up debris during the debris removal portion of the cycle of operation.

Abstract: A water screen comprises a revolving screen member, e.g., a band screen or a drum screen, and a washing device. The washing device, comprises a sprayer on one side of the downstream run of the screen member and a recovery channel on the opposite side of the downstream run of the screen member. On the same side as the recovery channel and between it and the sprayer is a mobile trough member. The trough transversely and obliquely from its leading edge adjacent the recovery channel, e.g. a band screen or a drum screen. The leading edge of the trough is maintained continuously in contact with the screen member which may be exclusively by the effect of gravitational force on the trough member.

Abstract: A trash rake is disclosed for cleaning the bars of a water intake bar screen. A carriage carrying a pan is mounted for movement parallel to the bar screen. Along the transverse edge of the pan proximate to the screen is a rake member whose teeth are received between adjacent bars during one direction of displacement of the carriage. A watertight recovery gutter for collecting foreign bodies, including living creatures, is arranged in continuity with the rake member and maintains the foreign bodies in water during the ascent of the pan. Preferably, the recovery gutter has a trapezoidal cross section and a transverse wall portion running directly into the rake member which makes an angle of at least 30.degree. with a horizontal plane when the rake member engages the bar screen.

Abstract: A continuous belt traverses a river through channels on the river bed and carries intercepted material to the river banks for separation of precious metals and gemstones therefrom. Method and apparatus claimed.

Abstract: A boom is mounted for pivotal movement about the center from which the arcuate shape of a filter screen is struck and a cleaner is pivoted to the free end of the boom. A single reversible drive unit is operatively connected to the cleaner for exerting a force thereto to tilt the cleaner toward a cleaning position. A stop operatively and rigidly connects the cleaner to the boom to transmit force from the cleaner to the boom as a pivotal force only after the cleaner is tilted to the cleaning position to thus rigidly connect the drive unit and cleaner to the boom.

Abstract: A bar screen with a screen cleaner has a vertically movable carriage with a rake pivotally connected thereto by pivot arms. A foldable lever assembly is pivotally connected to the carriage and to the pivot arms and assures a fully extended position and a folded position which correspond to a position of engagement of the rake with the screen and a position of disengagement of the rake with the screen, respectively. A lower stop engages the foldable lever assembly and moves it from a folded position to an intermediate folded position at the end of downward movement of the carriage and before the lever assembly reaches fully extended position so that the rake remains in a position of disengagement with the screen during downward movement of the carriage and is held in this position until the lever assembly is moved to fully extended position in response to upward movement of the carriage.

Abstract: This invention provides means to screen long, slender objects from a flowing fluid, and more particularly provides means to clear jammed objects therefrom. The screening means comprises a set of opposed, aligned, undulating surfaces, preferably formed as corrugated plates, located within a conduit, that can be moved apart to permit the removal of trapped debris. The plates are so mounted as to be transversely movable relative to the conduit, and are each movable relative to the adjacent plates so as to permit increasing the separation between adjacent plates when the plates are moved to outside of the conduit. The liquid screening means of this invention can usefully be included in a suction type dredging device, between the inlet nozzle and the pump.

Abstract: There is described a device for purifying liquids, with a grate, a toothed beam movable opposite thereto, and means to move said teeth in an endless path relative to said grate with a rising run and a falling run, in such a way that at the start of said falling run, said teeth perform a backward swinging to an unoperative position, and during the transition between the falling run and rising run, said teeth perform a further swinging in the same direction to a position wherein said teeth project anew through said grate.

Abstract: This invention provides dredging means having means to screen long slender particles wherein the long dimension extends in the direction of flow through a fluid-flow conduit. The screening means comprises a pair of opposing corrugated surfaces, the folds or corrugations on the opposing surfaces being substantially parallel, and separated by a distance, and having a wave length, determined by the size particle to be screened. Preferably, the corrugated surfaces are formed as a plurality of corrugated plates inserted within and extending along the direction of fluid-flow in a conduit. The axis of curvature of the corrugations or folds extend perpendicular to the flow of the stream.