JP2607805Y2 - Scum removal device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scum removing device constructed in a first or final settling tank or other processing tank.

[0002]

2. Description of the Related Art For example, a large amount of scum stays on the water surface of the first or final settling pond, and various measures have been taken to remove it.

As an effective solution to this problem, the applicant of the present invention has previously proposed a scum removing device which operates without power in conjunction with flight. The feature of this device is that it is a gutter-shaped member, and one side of the trough is installed in the pond so that it is below the surface of the water, and a part of the trough that is installed on the one side of the trough and floats above the surface of the water. It is kicked by a weir that can float up and down so as to repeat the state and the state of being submerged below the surface of the water, and a drive unit provided on a member that moves along a certain trajectory in the pond like a flight of a sludge attracting device. A device is provided with a cam as one of the constituent members and a transmission means for converting the motion of the cam into a motion in the direction in which the weir sinks, and a means for returning the weir to a floating state. According to this, the cam is kicked up by the roller attached to the flight that moves along the water surface, and the weir is pushed down via the lever arm to be submerged under the water surface. Invited in the trough It is adapted to be. Further, the weir floats again by the returning means due to its own buoyancy and the weight of the arm and the like, so that the attraction of scum is prevented. This exercise is repeated.

[0004]

[Problems to be solved by the device] By the way,
The scum removal device has a hollow weir.
Place it on the front side of the rough and project from the trough side between the weir and the trough.
The rubber base seal that has been put out is placed to prevent water from entering from the front.
It was configured to stop.

In this case, the rotary shaft is projected on both ends of the weir in the longitudinal direction.
Installed, and with the rotary shaft supported on the trough side,
The seal was designed to prevent water from entering . But,
The rotating shaft up to now is located slightly above the base end of the weir.
Because the hearts corresponded, the base seal and the outer circumference of the base end
Will always slide, resulting in damage to the base seal.
Seals due to wear or scum entering into the minute gap
It was not possible to secure sufficient sex.

The present invention has been made to solve the above-mentioned problems and the like, and its purpose is to seal the base seal.
It reduces the risk of wear and improves its sealing performance.
Providing a scum removal device that can be improved
To do.

In order to solve the above-mentioned problems, a device according to claim 1 is provided with a trough provided in a pond so that at least one side is below the water surface, and a part above the water surface provided on the one side of the trough. It was installed on a hollow weir that floats up and down so as to repeat the floating state and the submerged state, and a member that moves along a certain trajectory in the pond like the flight of a sludge attracting device. A scum removing device provided with a cam kicked by a driving unit as one of the constituent members, and transmitting means for converting the movement of the cam into movement in the direction in which the weir is retracted, and means for returning the weir to a floating state. And before
The weir has a semi-circular round base end.
In addition, at the base of the weir, both ends of the weir are wound around the weir.
The rotation shaft that can rotate is installed so that it protrudes outward.
The rotation center of the rotary shaft is on the outer circle of the base end.
While located slightly eccentrically downward, the trough side
Is a concave base sheet that contacts the outer circumference of the base end.
Is provided . According to a second aspect of the invention, in the first aspect, the rotary shaft is inserted and supported in a bearing fixed to a side plate portion provided on the trough side so as to be orthogonal to the longitudinal direction of the trough. The bearing is a spherical bearing. A third aspect of the present invention is the device according to the first or second aspect, wherein the base seal is held by a pressing piece from the inside of the trough, and the base of the pressing piece is detachably fixed from the inner side of the trough. ing.

[0005]

The present invention will be described in detail below with reference to the illustrated embodiments. 1, 2, and 3 show the first part of this invention.
1 shows an embodiment, FIG. 1 is a vertical sectional front view when the present scum removing device is installed in a sedimentation basin 1, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a sectional view taken along line III-III of FIG. Each figure is shown. Reference numeral 2 denotes a side wall of the sedimentation basin 1 which is opposed to the left and right sides, and end walls are formed orthogonally to the side wall so that the flattened rectangular sedimentation basin 1 is formed and a ceiling wall with an opening is formed. 3 is also formed.

The water surface 5 is below the water surface 5, that is,
In water, the chain 6 shown in FIG. 2 can be vertically circulated and driven, and a plurality of flights 7 attached to the chain 6 constitute a sludge attracting device. Flight 7
Draws in one direction the sludge that has settled on the bottom of the pond at the bottom (not shown). In FIGS. 1 to 3, the state when the vehicle is moving upward is shown. Then, at the end of each of the same flights 7 or at intervals, there are four
The bracket 8 that fixes the square tube is rotated by the resin roller 9.
It is mounted so that it can roll and is prevented from falling out to the side.
And a groove is formed in the part of the roller 9 that projects laterally.
Is made. In addition, 10 shows a chain bracket.

The roller 9 normally advances with only the upper part looking above the water surface 5, but in the case of this embodiment, the roller 9 passes slightly below the water surface 5. Of course,
It can be implemented in a system in which only the upper part is seen above the water surface 5 to proceed.

Reference numeral 12 is a communicating trough, which is opposite side walls 2 and 2.
The communication trough 12 is equipped with flanges 13 at both ends. The communication trough 12 is a so-called existing pipe that has been installed before the installation of the scum removing device. For example, a pipe-type scum schema (not shown) having a front opening serving as a scum inlet is provided between the two. Was installed.

Between the flanges 13 and 13, a trough 15 which is a main body of the scum removing device is provided with a bolt and a nut 16.
It is mounted in. The trough 15 has a rectangular gutter shape, and more specifically, includes a horizontal bottom wall, a front wall and a rear wall, and an auxiliary flange is formed at the upper end of the rear wall. And, on the left and right side end portions of the trough 15,
A side plate portion 17 having a through hole communicating with the communication trough 12 and a hole adapted to the flange 13 and having a rectangular projecting plate portion is fixed by welding. Other,
Reinforcing ribs 18 are fixed to the outer circumference of the trough 15 at appropriate positions in the longitudinal direction, and a bracket 19 which is an L-shaped channel member is laterally opposed to one side of the bottom wall as shown in FIG. It is firmly fixed.

Reference numeral 20 is an eyebolt, and two eyebolts are mounted on the auxiliary flange at the rear portion of the trough 15 and, for example, four are mounted on the upper ends of the left and right side plate portions 17, respectively, for a total of four. Used. Reference numeral 22 is an adjuster, which is a pair of left and right upper protrusions 23 and 2 having the respective holes.
3 is provided with a pair of left and right lower projecting pieces 24 that extend horizontally so as to form an L shape, and after the trough 15 is hung and carried in between the flanges 13, the upper projecting piece 23 is attached to the flange 13.
The flange 13 and the side plate portion 17 are temporarily fixed by bolts and nuts 16 so as to hit the back side of the communicating trough 12, the trough 15, and the adjuster 22.
Then, after the holes of the communication trough 12 and the trough 15 are aligned with each other, the bolts and nuts 16 are tightened, and then two adjusting bolts 25 which are erected from between the lower projecting pieces 23 are adjusted. Then, the trough 15 is adjusted so as to match the regular position. After that, the other bolts and nuts 16 ... Are tightened and fixed. Installation may be done by other procedures.

The front wall of the trough 15 is set lower than the water surface 5 by several tens of centimeters. Weir (float) 3 on the front side
It is attached so that 0 can move up and down. Same weir 3
As shown in detail in FIGS. 4 to 7, the reference numeral 0 indicates that the base end portion 31 is rounded in a semicircular shape and the tip end portion 32 is rectangular in cross section, and the inside thereof is hollow and is a hollow weir. It is 30. As shown in FIG. 1, the weir 30 has a long shape and is hollow so that it can return to the water surface by its own buoyancy.

Both ends in the longitudinal direction of the weir 30 are open,
A thick plate-shaped end plate 33 is fixed so as to close this opening. The end plate 33 and the weir 30 are welded to each other at the peripheral portion, and the base plate 31 of the weir 30 is provided on the end plate 33 side.
As shown in FIG. 4, the reinforcing pipe 34 is welded and fixed. Reference numeral 35 is the welded portion. A hole 36 is formed in the base of each of the end plates 33 on both sides, and a rotary shaft 37 is fixed in an outwardly protruding shape so that the base is inserted and fixed in the hole 36. The rotary shaft 37 is provided with a through hole 38 of the side plate portion 17.
It is rotatably supported by an underwater bearing 39, which is made of all resin and is fixed to the outer surface of the side plate portion 17 and is supported by a ball, while projecting outward through the.

The rotary shaft 37 supported by the bearing 39 is
As shown in FIG. 5, FIG. 6, and FIG. 7, it may be positioned at the semicircular center of the base end 31 of the weir 30, but here, the base end 31.
It is located eccentrically on the outer circle and slightly downward. On the other hand, reference numeral 41 denotes a base seal, which is made of rubber. The base seal 41 is a strip-shaped member having a concave tip end portion that comes into contact with the outer periphery of the base end portion 31, and the direction thereof is approximately 45.
The pipe 34 is parallel to the plate surface of the weir 30 that has slanted forward at an angle of
Its center is on an extension line slightly lower than the center of. The angle is about 45 °, which is attached to the receiving portion 42 formed at the upper end of the front wall of the trough 15 and projecting at an angle of 45 °, and to the rear surface of the front wall of the trough 15 via bolts and nuts 43. It is attached by being sandwiched between the pressing piece 44. A tip portion 45 of the base seal 41 has a semicircular recessed shape and abuts the base end portion 31 of the weir 30 from the outer circumference. In addition, since the pressing piece 44 includes the protruding portion 46 that partially protrudes into the trough 15, there is no risk that the attracted scum will be caught by the bolt / nut 43 and remain. Further, as shown in FIG. 4, the base seal 41 is appropriately refilled with another rubber or the like so that the base seal 41 also comes into contact with the end plate 33 and the rotary shaft 37 to obtain a sealing effect.

Reference numeral 48 denotes a side seal, which is made of a rubber plate. The side seal 48 is a scum between the end plate 33 and the side plate portion 17 as shown by an imaginary line in FIG. 4 and a solid line in FIG. The base is also sealed up to around the rotary shaft 37 so as to prevent the inflow of water. The end of the side seal 48 moves up and down together with the weir 30 while being in contact with the inner surface of the side plate 17. Incidentally, 49 is a stop bolt.

As shown in FIG. 1, a sickle-shaped engagement receiving member 52 having an engaging claw 51 on the outer periphery is attached to the tip of the weir 30 so as to rise upward. The receiving member 52 has a substantially arc shape. In addition, the engaging claw 51
As shown in FIG. 2, it does not come off easily and does not come off upward, and it is formed not only on the entire engaging receiving member 52 but only on the circumferential portion excluding the non-engaging surface 53 at the upper end. Has been done. An upper limit defining projection 54 is formed on the lower end side of the engagement receiving member 52.

On the other hand, reference numeral 57 denotes a cam (Naray plate) which is one of the transmission means. The cam 57 may be a one-step projection, but here it is a thin plate having two-step projections 58. . The cam 57 is attached to the horizontal tip portion 60 of the first transmission arm 59, and its position can be adjusted vertically. The first transmission arm 59 is fixed by a bolt to an arm shaft 62 rotatably supported by bearings 61, 61 mounted on the back flange of the trough 15.
The first transmission arm 59 has a cylindrical connecting portion in the middle, and is fixed by fitting the connecting portion around the arm shaft 62. Then, the end portion on the side opposite to the cam 57 slightly extends obliquely upward.

The first transmission arm 59 is shown in FIGS.
As shown in FIG. 5, the arm guides 64 mounted on the bracket 19 and horizontally extended to the rear of the trough 15 move vertically between the arm guides 64 while the left and right shakes are restricted. Then, when the back is put on the adjustable stopper 65 and the robot normally stands by and is kicked up by the roller 9, it becomes like a virtual line in FIG. This first
A second transmission arm 67, which is parallel to the transmission arm 59, is connected to the side of the transmission arm 59, and the connection is made by a connecting member 68 shown in FIG.
And bolts.

The second transmission arm 67 is also connected to the arm shaft 62 by a bolt through a square tubular portion. Both the first and second arms 59 and 67 move together and swing. Incidentally, 69 is a manual lever that stands up from the arm shaft 62. Then, the second transmission arm 67 extends forward beyond one side above the trough 15. A bracket 70 is attached to the middle of the horizontally extending portion of the arm 67 as shown in FIG. 2, and a U-shaped hanging bracket 71 is fixed to the front outer side of the bracket 70.

On the suspension bracket 71, a push-down member 72, which is a pair of vertically elongated strip-shaped members, is combined with a pin 73.
It is suspended by. A plurality of holes are provided at the upper end of the pressing member 72, and the height of the pressing member 72 can be adjusted by the pin 73. Further, a plurality of holes are also formed in the lower end of the pressing member 72, and one of them has an engaging pin 74.
Is passed through to engage with the engaging claw 51 from above.

Further, the push-down member 72 is kept in a vertical state by the stopper shaft 75 and the pulling spring 76 protruding from the bracket 70 when not engaged. Further, a tube 77 is fixed to the upper side of the tip of the second transmission arm 67, and a weight 78 is attached therein by a bolt 79 so that the position of the tube 78 can be adjusted. The weight 78 is a rod 8.
The movement is adjusted by 0.

Next, the operation of the scum removing device will be described. 1 to 3 show a state in which the roller 9 has not yet reached the cam 57. Then, when the roller 9 hits the cam 57, the cam 57 is lifted up to a virtual line. As a result, the push-down member 72 is lowered via the first and second transmission arms 59 and 67, and the engagement pin 74 at the lower end is engaged with the engagement claw 51 to push down the engagement receiving member 52.
As a result, the weir 30 is pushed down. When the weir 30 is submerged in the water over the water surface 5, the scum on the water surface is attracted into the trough 15 together with the water. The attracted scum and water flow into one of the adjacent troughs through the connecting trough 12, and sequentially flow while maintaining their directionality.

When the roller 9 passes the cam 57, the cam 57 is lowered, the first and second transmission arms 59 and 67 respond in opposite directions, and the pressing member 72 is lifted upward.
Since the weir 30 has buoyancy, it floats together with the pressing member 72, but at the end, the pressing member 72 is lifted independently, and is completely separated from the pressing member 72. Since the weir 30 side can move independently in this separated state, for example, even if the level of the water surface 5 changes, only the weir 30 can follow this.

Further, when the weir 30 fluctuates as low as about the lower line of the imaginary line in FIG. 2, the depressing member 72 is present on the non-engaging surface 53, so the weir 30 is Do not respond. Further, the upper limit defining projection 54 prevents the weir 30 from further levitating by hitting the engaging pin 74 when the weir 30 floats considerably upward.

[0024] Incidentally, Sekimototan as the rotation axis 37 of the weir of the
If the weir 30 is eccentrically positioned at one point on the outer circumference of the part, as can be seen by assuming a state in which the weir 30 is pushed down around the coaxial 37, the deformation of the base seal 41 is suppressed to a very small level, and the sealing effect is effectively achieved. maintain. Especially, the base seal 41 is
Since one point is always caught and the contact state with the weir 30 is maintained,
Scum from one person enters and scum gets caught
The risk of water ingress is very low.
It

The base rotation fulcrum 82 of the arm may be located above the trough 15, as shown by the phantom line in FIG. Further, a fulcrum is provided in front of the pressing member 72, and
It is also possible to support one arm extending in the left direction and the right direction and to provide the pressing member 72 on the arm.

Further, the cam may be freely driven by a flight roller that moves on the bottom of the pond. Further, the first and second transmission arms 59 and 67 can be integrated.

8 and 9 show additional examples . In the same example , the same components as those in the above embodiment are designated by the same reference numerals. However, reference numeral 85 is a rotating shaft, which is passed through the base end portion of the weir 30. Of course, you may support by an eccentric shaft like the said Example. 86 is a lever kicked by the roller 9, and the valve 87 opens by being kicked and the submersible pump 88
The water in the pond is supplied into the upper water tank 90. Of course, a relief valve is provided between the pump 88 and the valve 87.

The water tank 90 is elastically supported by a spring 91, and an elevating shaft 92 extending from the center of the bottom of the water tank 90 is guided by a guide roller 93 so that the water tank 90 can be moved up and down. 94 is a bracket, and 95 is a pedestal. By supplying water into the water tank 90, the tank 90 is gradually lowered against the spring 91, and the pressing member 72 is engaged with the engaging claw 51.
, The engagement receiving member 52 is lowered and rotated, and the weir 30 is submerged below the water surface. As shown in FIG. 9, a thin slit 96 is formed in the water tank 90, from which water is gradually discharged. Therefore, the supply of water is stopped by the roller 9 passing the lever 86, and the water continues to come out from the narrow slit 96, so that the water tank 90 gradually rises due to the buoyancy of the spring 91 and the weir 30, and the pressing member 72. Moves away from the engagement receiving member 52. The pressing member 72 further rises. Engagement receiving material 5
Since 2 is released from the pressing member 72, the weir can follow this even if the water surface level changes. This point is the same as the above-mentioned embodiment. The narrow slit 96 is a brush 97.
It is always cleaned in.

FIG . 10 also shows an additional example . Also in this example , the same reference numerals are attached. 1
00 is a lever kicked by the roller 9, and the lever 100
Activates the control valve 101. Same valve 1
Reference numeral 01 is a spring with a return spring and is composed of a first block 102 and a second block 103. When the lever 100 is kicked, the first block moves to the second block. That is, the water from the submersible pump 103 is supplied to the water tank 104. This continues for a certain period of time, which causes the water tank 10
4 descends against the spring 105. In the frame 106,
An elevating shaft 107 of the water tank 104 can be moved up and down, and an operating lever (main part of one-way engaging means) 109 with a weight 108 is rotatably attached to the lower end of the shaft 107. When the lifting shaft 107 is lowered, the lever 109 swings counterclockwise due to the weight of the weight 108, and the engaging hole 110 formed at the tip end side of the lever 109 is twisted to engage with the push-down bar 111 and push down. . Bar 11
1 is vertically guided by the guide roller 112, and pushes down the interlocking rod 113 connected to the lower end thereof. Then, the rod 113 rotates the bell crank 114 to rotate the cam 11
The weir 30 is pushed down via 5.

When the roller 9 passes the lever 100,
The valve 101 moves to the first block 102, and the water in the water tank 104 is discharged as shown by a virtual line. As a result, the water tank 104 and the elevating shaft 107 ascend, and the push-down bar 111 also ascends due to the buoyancy of the weir 30. And finally, the operating lever 109 becomes horizontal,
It is stopped by the stopper 116. As a result, the weir 30 is completely floated, and the push-down bar 111 freely moves up and down in the engagement hole 110, so that the water level of the weir 30 can be changed. Incidentally, 117 is an overflow port 11
8 adjusting plate.

FIG. 11 shows an additional example . In this example , the weir 1 is supported by the rotating shaft 121.
The foamed resin 122 is provided in most of the inside of 20, and only the upper end of the tip is left as a cavity (water tank portion) 123. A water supply tube (flexibility) 124 is connected to one end of the cavity 123, and a drain slit 126 whose opening amount can be adjusted by an adjusting plate 125 is formed at the other end. Water supply tube 124 to cavity 123
When water is supplied to the inside, the water is discharged from the drain slit 126, but the amount thereof is small, and therefore, the water gradually accumulates in the cavity, so that the weir 120 descends and attracts scum. When the water supply is stopped, the water inside is discharged from the slit 126, and the weir 120 floats due to the buoyancy of the resin 122.

FIG. 12 shows an additional example . In this example , a water tank 132 is provided above the tip of the weir 130 via a bracket 131, and the weir 130 is a hollow type and can float by itself. When water is supplied into the water tank 132, the water is discharged from the slit 133, but the amount thereof is small, so that the water gradually accumulates and pushes down the weir 130. When the supply of water is stopped, the water tank 132 becomes lighter due to the discharge of water from the slit 133, and the weir 130 floats.

FIG. 13 shows an additional example . In this example , a water tank 136 is provided above the weir 135.
6, the weir 135 is pushed down and interlocked. Water is supplied to the water tank 136 through the tube 137, and the weight thereof lowers around the rotating shaft 138 to push down the weir 135. Then, by draining water from the slit 139 provided at the lower end of the weir, the water tank 1
As the inside of 36 becomes empty, the buoyancy of the weir 135 acts and the weir 135 floats.

According to the first aspect of the present invention, a trough is provided in a pond so that at least one side is below the water surface, and a state where the trough is provided on the one side of the trough and partially floated above the water surface and below the water surface. A hollow weir that can be floated up and down so as to repeat the submerged state, and a cam kicked by a drive unit provided in a member that moves by following a certain trajectory in the pond like the flight of a sludge attracting device. A scum removing device comprising: one of the constituent members, a transmission means for converting the movement of the cam into a movement in the direction in which the weir is submerged, and a means for returning the weir to a floating state, wherein the weir is , Its base is a semicircle
It is formed into a round shape, and the weir has a longitudinal direction.
The rotation axis that allows the weir to rotate freely at the base ends of the opposite ends is outward
The center of rotation of the rotary shaft is
Positioned on the outer circumference of the base end and slightly eccentric to the bottom
On the other hand, the trough side contacts the outer circumference of the base end.
Since the base seal having a concave shape is provided, it is possible to provide a scum removing device capable of reducing the risk of wear of the base seal and improving the sealing performance thereof. It became so. According to a second aspect of the present invention, in the scum removing device according to the first aspect, the rotating shaft is inserted and supported in a bearing fixed to a side plate portion provided on the trough side so as to be orthogonal to the longitudinal direction of the trough. At the same time, since the bearing is a spherical bearing, the bending of the weir, which is generally long and subject to water pressure, and which easily bends, is effectively absorbed by the combination of the rotating shaft and the spherical bearing. The rotation of the weir becomes smooth and the weir can be moved up and down easily. The invention according to claim 3 is the scum removing device according to claim 1 or 2, wherein the base seal is held by a pressing piece from the inside of the trough, and the base of the pressing piece is
Since it is detachably fixed from the inside of the trough, the adjustment of the sealing condition of the base seal can be easily and safely performed by the removal work from the inside of the trough.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a scum removing device showing an embodiment of the present invention .

FIG. 2 is a sectional view taken along line II-II of FIG.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 5, showing a main part of one embodiment .

5 is an X-direction arrow view of FIG. 4;

6 is a sectional view taken along line VI-VI of FIG.

7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is an explanatory diagram showing an additional example .

FIG. 9 is a view on arrow Y of the same example .

FIG. 10 is an explanatory diagram showing an additional example .

FIG. 11 is a perspective view showing an additional example .

FIG. 12 is a sectional view showing an additional example .

FIG. 13 is a schematic sectional view showing an additional example .

[Explanation of symbols]

1 ... Sediment pond, 5 ... Water surface, 7 ... Flight, 8 ... Bracket
To, 9 ... roller, 15 ... trough, 17 ... side plate part, 30
... weir, 31 ... base end, 37 ... rotating shaft, 41 ... base seal, 43 ... bolt / nut, 44 ... pressing piece, 48 ... side seal, 57, 59, 67 ... transmission means,

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 1/40 B01D 21/24

Claims (3)

(57) [Scope of utility model registration request] 1. A trough provided in a pond so that at least one side is below the water surface, and a state in which the trough is provided above the one side and partially floated above the water surface and submerged below the water surface are repeated. And a hollow weir that can be floated and lowered,
A cam kicked by a drive unit provided in a member that moves along a certain trajectory in a pond like a flight of a sludge attracting device is used as one of the constituent members, and the motion of the cam is directed in the direction in which the weir is submerged. A scum removing device comprising a transmission means for converting into a motion and a means for returning the weir to a floating state, wherein the weir has a semicircular round base end.
Both of the weirs have the same weir at the base end of both ends in the longitudinal direction.
The rotating shaft that allows the
The center of rotation of the rotary shaft is on the outer circumference circle of the base end.
And located eccentrically to the lower side, while the trough
On the side, there is a concave base sheath that contacts the outer circumference of the base end.
A scum removing device characterized in that a scum is provided . 2. The rotating shaft is inserted and supported in a bearing fixed to a side plate portion provided on the trough side so as to be orthogonal to the longitudinal direction of the trough, and the bearing is a spherical bearing. The scum removing device according to 1. 3. The scum removing device according to claim 1, wherein the base seal is held by a pressing piece from the inside of the trough, and the base of the pressing piece is detachably fixed from the inner side of the trough.