JP3628757B2 - Magnetic chain belt - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a driving force transmission device for a track, and more specifically, both a chain and a belt. The present invention relates to a driving force transmission device that can exert a magnetizing driving force on a track using a magnet.
[0002]
[Prior art]
Conventionally, a so-called wheel is generally used as a driving force transmission device of a transport device for a track. However, the transmission of the driving force by the wheel only relies on the frictional force between the wheel and the wheel, causing a problem that the wheel slips and a loss occurs in the transmission of the driving force. Therefore, it is considered that this problem can be solved by providing a mechanism that exhibits some magnetic force between the track and the driving force transmission device.
[0003]
On the other hand, in the field of conveyors, there are so-called magnetic conveyors for conveying a casing made of a magnetic material such as an iron drink can. In the magnet type conveyor, a magnet type belt conveyor formed by attaching a so-called magnet catcher in which a magnet 91 is held by a yoke 90 having a U-shaped cross section to the belt 9 as shown in FIG. There is a magnetic chain conveyor in which a magnet 93 is attached to such a chain 94 along the longitudinal direction of the chain 94. The magnet 93 is sandwiched between the yokes 92 on both sides. In the figure, reference numeral 8 denotes a case to be transported.
[0004]
Therefore, if these magnetic conveyors are formed endlessly to form a driving force transmission device, and the object to which the driving force transmission device is magnetically attached is replaced with a track made of a magnetic material, the track and the magnet type driving force transmission device The magnetic force is exerted between the two and the driving force is efficiently transmitted to the track without any loss.
[0005]
[Problems to be solved by the invention]
However, the construction of the magnetic belt conveyor shown in FIG. 9 as a driving force transmission device has the following problems. That is, when a magnet is attached to a yoke having a U-shaped cross section, since an adhesive such as an epoxy is usually used, the magnet is likely to fall off the yoke due to the magnetic adhesion force between the magnet and the track.
[0006]
Also, as shown in the figure, it is necessary to place the magnet horizontally in the yoke so that different magnetic poles appear on the yoke and the magnet surface, but the surface area increases, so the belt is used as a drive device. A moment works between the part that has been separated from the track and the part that is bonded to the track at the part that has entered the track side from the drum and the part that has moved from the track side to the driven drum. A force to pull away is generated. As a result, there arises a problem that the portion of the belt holding the yoke is gradually broken and the yoke falls off the belt.
[0007]
In addition, a thin yoke material is used to reduce the overall weight because the combination of the yoke and magnet is attached to the belt, which is a relatively weak structure, but the yoke wears easily, and the yoke emits. There is a problem that the noise becomes worse and the magnetic adhesion force to the track is reduced. For this reason, as shown in the figure, the gap between the magnet surface and the track must be reduced to increase the magnetizing force. However, this causes the gap to decrease as the yoke wears. The life of the yoke will be shortened and will be replaced in a short time.
[0008]
In addition, since the magnetizing force by a magnet does not generate | occur | produce between a belt, a drive drum, and a driven drum, there exists a problem which a belt slips in a drive drum part and a loss occurs in transmission of a drive force. Further, since the belt extends for a long time, it is necessary to apply tension to the belt by using a take-up or the like, and periodically apply tension again. In the case of a rubber belt, the life is relatively short.
[0009]
On the other hand, there are the following problems in using the magnetic chain conveyor shown in FIG. 10 as a driving force transmission device. In other words, since the magnet is attached so as to be long in the longitudinal direction along the longitudinal direction of the chain, when the chain reaches the driving drum and the driven drum as the driving device, the bending angle at the connecting portion of the chain is large. Bending stress is strongly applied, and the pins connecting the chains are immediately broken, making it unusable for use. This is a significant problem that becomes more pronounced as the diameter of the drum decreases.
[0010]
In addition, as shown in the figure, the chain has a lot of rattling and noise, and for the convenience of incorporating the magnet into the chain, it is stopped by passing a screw or pin through the shaft hole of the magnet. There is also a problem that when a hole is made in a magnet, the magnet is easily broken.
[0011]
Therefore, the present invention solves the above-described problems, and provides a strong driving force with a strong magnetizing force, and also makes it difficult for the magnet to fall off the yoke, allowing a large gap between the surface of the magnet and the track. Another object of the present invention is to provide a completely new driving force transmission device that has a long service life, is structurally strong, and has low noise.
[0012]
[Means for Solving the Problems]
In the present invention, the configuration is as follows in order to solve the above problems.
[0013]
That is, the magnet type chain belt of the present invention includes two yokes and a magnet sandwiched between the two yokes so that both poles face the yoke side, and the widthwise end of the magnet is magnetically attached to the track of the yoke. A plurality of yoke pairs that are paired with each other, two rotating shafts, and connecting fittings that are attached to both ends of each of the yoke pairs. A plurality of connecting means disposed between one end of each of the yoke pairs, and one end of one rotating shaft of the connecting means disposed on both sides of each of the yoke pairs; The first bearing in which the shaft hole to be inserted is formed, and the one rotation of the connecting means that is fitted to the other end portion in the longitudinal direction of each yoke pair and disposed on both sides of each yoke pair. A shaft into which the other end of the dynamic shaft is inserted There and a second bearing which is formed by the respective said bearing and said connection means, characterized in that formed by connecting a plurality of the yoke pairs endlessly.
[0015]
The magnet type chain belt of the present invention is characterized in that the shape of the end portion in the width direction magnetically attached to the track of each of the yokes is formed according to the surface shape of the track.
[0016]
The magnet type chain belt of the present invention is characterized in that a spacer made of a nonmagnetic material is provided between the two yokes forming a pair, and a magnet is fitted through the central portion of the spacer. .
[0017]
The magnet type chain belt according to the present invention is characterized in that the connecting member provided between the yoke pair has a recess or a hole that can mesh with the teeth of the sprocket.
[0018]
[Action]
1. Since the magnets are interleaved and integrated so that both poles of the magnets face the yoke, the N and S poles appear at the ends of the two yokes. Can be magnetized on the track. However, this is formed so that the length in the direction perpendicular to the track is longer and is connected horizontally in the longitudinal direction of the track, so that the magnetic force on the track is longer in the track direction. Compared with the case where it is formed so as to be sparsely arranged, it is significantly larger. Further, since the total width of the two yokes and the magnet is extremely small with respect to the longitudinal direction of the track, the bending angle at the drum portion is extremely small. As a result, the two yokes and the magnet at this portion The bending stress applied to the pair is almost negligible. Further, since the yoke can be made thick, the wear of the yoke is reduced, the life is extended as a whole, and the noise generated by the yoke can be reduced.
[0019]
Since the magnet type chain belt is stretched between the driving drum and the driven drum, it needs to be connected at least inwardly, that is, bendable to the drum side by the connecting means. Also, since the gap between the end of the yoke that is magnetically attached to the track and the end of the magnet is formed so that the magnet is retracted, the end of the yoke that is magnetically attached to the track Even if the part wears away when it moves on and off the track, it may be considered that this wear does not reach the magnet. In particular, since the N pole appears at the end of one yoke and the S pole appears at the end of the other yoke, the gap can be made as deep as necessary.
[0020]
When the present invention is used for a drive drum made of a magnetic material, the two yokes can be magnetically attached to the drive drum as well as the track. Transmission of driving force to this magnet type chain belt becomes more efficient. Moreover, the structure which tensions between drums like a conveyor is not requested | required. Also at this time, the gap can be taken to the required depth on the side facing the drive drum. Further, when the present invention is used for a drive drum or the like made of a magnetic material, the following special effects are observed. In other words, if the drive drum is arranged forward in the direction of travel, the magnet type chain belt appears N pole and S pole at the ends of the two yokes and strongly adheres to the drive drum. When approaching the track, a magnetic circuit is generated on the track side, and the magnetic force is exerted on the track. Then, since the magnetic adhesion force on the drive drum side is halved, the magnetic chain belt at this portion can be easily separated from the drive drum. On the other hand, the magnet type chain belt strongly adheres to the track and exerts a driving force, but when it reaches the driven drum from the track, a magnetic circuit is also generated on the driven drum side, and the magnetic force is also applied to the driven drum. To come out. Then, since the magnetizing force on the track side is halved, the magnetic chain belt at this portion can be easily separated from the track. It can be said that this is a switching action. As a result, the magnet type chain belt is more smoothly rotated. Although the above description is slightly different depending on the rotation direction of the drum, the description is omitted because it can be easily understood. When the gap is formed at both upper and lower ends of the yoke and the connecting means provided between the yokes is connected so as to be able to bend in both the inner and outer directions, when the yoke, for example, the track side is worn, it is worn by returning inside and outside. The side that has not been replaced can be replaced with the track side.
[0021]
For example, when the connecting means is composed of a magnetic material bearing and a shaft, and there is a magnetic field around the yoke, the wear powder generated from the bearing and the shaft adheres between the bearing and the shaft and is long. In the meantime, it has been found that this wear powder is crushed to the micron order and plays a role of lubrication, so-called bearing effect.
[0022]
2. In the configuration in which the front corner of the front yoke and the rear corner of the rear yoke are sharpened on the side that is magnetically attached to the raceway, it is smoother than when there is a corner when coming into contact with the raceway. There is an effect performed.
[0023]
3. In the configuration in which the shape of the end of the yoke that is magnetically attached to the track is formed in accordance with the surface shape of the track, it can be in close contact with the track, and the magnetizing force on the track will be stronger, and it will go straight on a straight track And followability on a curved orbit is good.
[0024]
4). In the configuration in which a spacer made of a nonmagnetic material is interposed between the yokes, and the magnet is fitted through the central portion of the spacer, it is possible to more effectively prevent the magnet from falling off between the yokes. It can also be used for positioning when interposing magnets between yokes. In addition, there is no problem of magnetic short-circuiting between the yokes due to wear powder generated from the yokes. That is, the magnet is completely protected by the spacer.
[0025]
5. In the configuration in which the connecting means provided between the yokes has a recess or hole that can mesh with the sprocket teeth, it is assumed that the sprocket is provided on the drum. When the driving drum is mainly made of a non-magnetic material, it is possible to prevent a transmission loss of driving force from the driving drum to the magnet chain belt. Of course, this configuration is extremely effective even when the driving drum is made of a magnetic material. This is also effective when the diameter of the drive drum is relatively small. The recess or hole can be selected depending on the shape of the sprocket teeth used. If a sprocket is also used on the driven drum side, this configuration can be used as it is.
[0026]
【Example】
Examples of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these examples.
[0027]
1 to 3 show a first embodiment of the present invention. The magnet 1 is placed between the two plate-like yokes 2 and 2, and a gap G is formed between the end of the yokes 2 and 2 in the width direction and the end of the magnet 1 in the width direction so that the magnet 1 retreats. In addition, a pair of yokes are formed by arranging the poles of the magnet 1 so as to face the yokes 2 and 2, and bearings are provided at the ends of the pair of the yokes 2 and 2, that is, the pair of yokes. 3 are fitted and integrated, and a plurality of pairs of the yokes 2 and 2 and the magnet 1 are formed so that the length in the direction perpendicular to the track W is long and horizontally arranged in the longitudinal direction of the track W. is, None of the magnet chain belt with and foldable to continuously arranged more endless connection means having a connecting fitting which will be described later this like.
[0028]
In the above, the yoke 2 has an I-shaped cross section, a shallow fitting groove 20 for fitting the magnet 1 on one side of the side portion, and a bearing made of a non-magnetic material on the other side. A shallow fitting groove 21 for fitting 3 is formed. Reference numeral 31 denotes a fitting groove formed in the bearing 3 for fitting into the end of the pair of the yokes 2 and 2 and the magnet 1, and reference numeral 30 denotes a shaft for inserting a rotating shaft 41 described later. It is a hole. The bearing 3 has a posture orthogonal to the pair of the yokes 2, 2 and the magnet 1, and the shaft holes 30 are positioned on both sides of the yokes 2, 2.
[0029]
Two hollow collars 40 are provided between the two connecting brackets 4, 4, and rotating shafts 41, 41 are inserted into the collars 40, 40. Both end portions are rotatably inserted into the shaft hole 30 of the bearing 3, and the other one is inserted into the shaft hole 30 of the bearing 3 of the set of the adjacent yokes 2, 2 and the magnet 1, and these are endless. A chain belt MCB is configured in a continuous manner. The reason that the chain belt is called is that the pair of the yokes 2 and 2 and the magnet 1 are formed so that the length in the direction perpendicular to the track W is long, and is arranged horizontally in the longitudinal direction of the track W. This is because the belt is correct in terms of a point, and is endlessly connected with a coupling metal fitting so that it can be bent, and the chain is correctly expressed, and both properties are effectively expressed (FIGS. 2 and 2). 3).
[0030]
Now, since the magnet 1 is integrated between the two yokes 2 and 2 so that both poles of the magnet 1 face the yokes 2 and 2 and are integrated, the end portions of the two yokes 2 and 2 are integrated. N pole and S pole appear in. Thus, the yokes 2 and 2 can be magnetically attached to the track W. However, this is formed so that the length in the direction perpendicular to the track W is long, and is arranged horizontally in the longitudinal direction of the track W, so that the magnetic force on the track W is the same as the length in the track direction. Compared with the case where it is formed so as to be longer and sparsely arranged, the effect is that it is belt-like. Another characteristic is that the bending angle at the drum portions 5 and 50 is extremely small, and the bending stress applied to the pair of the two yokes 2 and 2 and the magnet 1 is almost negligible at this portion (chain). The effect of being in the shape). Further, since the yokes 2 and 2 can be made thick, the wear of the yokes 2 and 2 is reduced, the life is increased as a whole, and noise generated by the yokes 2 and 2 can be reduced.
[0031]
In this embodiment, since the N pole appears at the end of one yoke and the S pole appears at the end of the other yoke, the gap G between the ends of the yokes 2 and 2 and the end of the magnet 1 is shown. Even if the end of the yoke 2, 2 that is magnetically attached to the track W wears away from the track W, it may be considered that this wear does not reach the magnet 1. . In particular, the gap G can be taken as deep as necessary. In addition, it is also preferable to perform a process in which a filler is injected into the gap G later.
[0032]
When the drive drum 5 used in this embodiment is made of a magnetic material, the two yokes 2 and 2 are magnetically attached to the drive drum 5 as well as the track W. Therefore, the transmission of the driving force from the driving drum 5 to the magnetic chain belt becomes more efficient. Also at this time, the gap G can be set to a required depth on the side facing the drive drum 5.
[0033]
In the case where the drive drum 5 is made of a magnetic material, in this embodiment, N poles and S poles appear at the ends of the two yokes 2 and 2, and are strongly magnetized on the track W (strength at point i). H) After that, when the drive drum 5 is reached (point B), a magnetic circuit is also generated on the drive drum 5 side, and a magnetic adhesion force is exerted on the drive drum 5 as well. Then, the magnetizing force on the track W side is halved, so that the effect of facilitating the separation of the magnet type chain belt from the track W at this portion is obtained (the strength H / 2 with respect to the drive drum 5 at point B). Yes, strength H / 2) with respect to orbit W. That is, a switching effect for facilitating the separation of the magnetic chain belt from the track W occurs at point B.
[0034]
In the present embodiment, the connecting bracket portion can be bent in both the inner and outer directions. Therefore, when the yokes 2 and 2 are worn, for example, on the track W side, the inner and outer sides are not turned back. The side can be changed to the track W side. In addition, there is a magnetic field around the yokes 2 and 2 in the return path, and for example, wear powder of the yokes 2 and 2 adheres between the shaft hole 30 of the bearing 3 and the rotation shaft 41 of the coupling metal 4 so-called Since this produces a bearing effect, it is not necessary to add lubricating oil to this part, and wear of the rotating shaft 41 is also reduced.
[0035]
In addition, as another feature of the present embodiment, it can be raised that a gap is formed between the collars 40, 40 spanned between the two connecting fittings 4. This is because if the drive drum 5 is made of a non-magnetic material and the sprocket is formed on the drive drum 5, the teeth of the sprocket can use the gap. The sprocket is also effective when the diameter of the drive drum 5 is small. The shape and size of the sprocket teeth are arbitrary as long as the gap can be used.
[0036]
4 and 5 show a second embodiment of the present invention. The first feature of this embodiment resides in that the magnet 1 is interposed between the yokes 24 and 24 via the spacer 22 as shown in FIG. A fitting hole 23 is opened at the center of the spacer 22, and the magnet 1 is fitted into the fitting hole 23. As a result, the positioning of the magnet 1 between the yokes 24 and 24 is easy and reliable, and there is an effect that care is not taken to fix the magnet 1. Further, since there is no apparent gap G as in the first embodiment, there is no problem that the abrasion powder generated from the yoke 24 and the like magnetically shorts between the yokes 24 and 24.
[0037]
The second feature of this embodiment resides in that the spacer 22 containing the magnet 1 and the yokes 24 and 24 are crimped by the crimping tool 27 at both ends thereof. An insertion hole 28 for inserting the spacer 22 and the ends of the yokes 24 and 24 is opened at the center of the crimping tool 27. In addition, instead of the crimping tool 27 made of a nonmagnetic material, for example, a configuration in which a Kevlar (registered trademark) fiber is wound around the part and fixed with an adhesive or the like is also possible. Although both ends are likely to be noise sources, an effect of suppressing noise can be seen with thickly wound fibers such as Kevlar.
[0038]
The third feature of the present embodiment resides in that a bearing 25 having a shaft hole 26 is formed integrally with the yoke 24 and a connecting fitting that connects adjacent yokes 24. The left and right rotating shafts 41 and 41 are inserted into the connecting fitting 42 having an oval cross section and caulked, and a hard rubber filler 43 is injected between the rotating shafts 41 and 41 to solidify it. It is made up of. Due to the aging of the filler 43, it is strongly bonded to the connecting fitting 42 and the rotating shafts 41, 41. The connection fitting has a spring property.
[0039]
The fourth feature of this embodiment resides in that a radius r is added to the corner of the yoke 24 on the side magnetically attached to the track W. In other words, there is an effect that when moving on and off the track W, it is performed more smoothly than when there is a corner. The corner r on the drums 5 and 50 side may also be rounded.
[0040]
6 and 7 show a third embodiment of the present invention. In the present embodiment, the shape of the end of the yoke 29 and the end of the spacer 22 on the side magnetically attached to the track W is matched with the surface shape R of the track W in the combination of the yokes 29 and 29 and the spacer 22. Are molded and provided with a curved portion R. In addition, as the track | orbit W in a present Example, it is set as the example which employ | adopted the pipe track | orbit.
[0041]
According to this configuration, since the yokes 29 and 29 can be in close contact with the surface shape R of the track W, the magnetic adhesion force to the track W becomes stronger, and the linearity on the straight track and the curved track This produces an effect of good followability. The shape of the end of the yoke 29 and the end of the spacer 22 may be determined according to the shape of the track. For example, even if it is a flat track, the surface of the yoke 29 is corrugated along the track. If the shape of the part and the end of the spacer 22 are matched to this waveform, this can be used as a guide and prevention of wheel removal.
[0042]
Next, FIG. 8 shows a fourth embodiment of the present invention. This embodiment relates to a spacer 22 incorporating the magnet 1 of the second embodiment described above and a non-magnetic bearing 35 applied to the yokes 24 and 24. There are fitting holes 39 for fitting the spacers 22 and the end portions of the yokes 24, 24, and on both sides thereof, two bearing portions 37 project from one side and the bearings on the other side. A bearing portion 36 having a shape in which the portion 37 just meshes is projected. A shaft hole 39 is opened at the center of the bearing portion 36, and a shaft hole 38 is opened at the center of the bifurcated bearing portion 37. Thus, adjacent spacers 22 and yokes 24, 24 are connected by bearings 35 fitted to both ends. That is, the adjacent bearing portion 36 is inserted into the bifurcated bearing portion 37, and the shaft holes 38 and 39 are pivotally held together by pins.
[0043]
In the first and second embodiments described above, in the set of the yokes 2 and 2 and the magnet 1 and the set of the spacer 22 and the yokes 24 and 24 in which the magnet 1 is built, adjacent members are connected. They are connected via two rotating shafts 41, 41 of the metal fitting 4 and the connecting metal fitting 42. On the other hand, in the present embodiment, since the one corresponding to the two rotation shafts 41 and 41 is a single pin for stopping the shaft holes 38 and 39, the spacer 22 and the yokes 24 and 24 are adjacent to each other. The distance between the groups is extremely close, and as a result, the magnetic chain belt as a whole exhibits a strong magnetic adhesion.
[0044]
In the present invention, a plurality of pairs of yokes and magnets are formed so that the length in the direction perpendicular to the track is long and arranged like a belt. As long as it is characterized in that it is formed in a chain-like manner by connecting means provided between the yokes, it is not limited to the above-described embodiment, and the type, size, shape, and interposition method of the yoke and magnet Etc., the arrangement of the entire magnet polarity may be determined as appropriate, the type of connecting means provided between the yokes is also arbitrary, and the conveyor chain can be used for any conveying device. A combination of this magnet type chain belt and a drum or a motor is also within the scope of the right of the present invention, and a case where the present magnet type chain belt is applied to a wheel or the like having one rotation center is also the present invention. Is the scope of rights.
[0045]
【The invention's effect】
As described above, in the present invention, a magnet is set between two yokes, and a gap is formed between at least one end of the yoke that is magnetically attached to the track and the end of the magnet so that the magnet side moves backward. In addition, the magnets are integrated so that both poles face the yoke, and a plurality of pairs of yokes and magnets are formed so that the length in the direction perpendicular to the track is long. It is a completely new driving force transmission device that is arranged horizontally and is connected to a pair of adjacent yokes and magnets so that they can be bent endlessly and at least inwardly by connecting means provided between the yokes. This is a magnetic chain belt.
[0046]
As a result, the present invention provides a strong driving force with a strong magnetizing force, and it is difficult for the magnet to fall off from the yoke, allowing a large gap between the surface of the magnet and the track to have a long life, and a structural Has succeeded in providing a completely new driving force transmission device that has the effect of being strong and low in noise, and has achieved the intended purpose.
[Brief description of the drawings]
FIG. 1 is a partially exploded perspective view of a first embodiment of the present invention.
FIG. 2 is a development plan view of the embodiment.
FIG. 3 is a schematic side view of the embodiment.
FIG. 4 is a partially exploded perspective view of a second embodiment of the present invention.
FIG. 5 is a perspective view of a spacer 22 and a magnet 1 according to the embodiment.
FIG. 6 is a partially exploded perspective view of a third embodiment of the present invention.
FIG. 7 is an explanatory diagram of a use state of the embodiment.
FIG. 8 is a perspective view of a bearing 35 portion according to a fourth embodiment of the present invention.
FIG. 9 is an explanatory diagram of a conventional magnetic belt conveyor.
FIG. 10 is a partial plan view of a conventional magnetic chain conveyor.
[Explanation of symbols]
1 Magnet 2 Yoke 20 Fitting groove 21 Fitting groove 22 Spacer 23 Fitting hole 24 Yoke 25 Bearing 26 Shaft hole 27 Clamping tool 28 Insertion hole 29 Yoke 3 Bearing 30 Shaft hole 31 Fitting groove 32 Bearing 33 Shaft hole 34 Fitting Joint hole 35 Bearing 36 Bearing portion 37 Bearing portion 38 Shaft hole 39 Shaft hole 4 Connecting bracket 40 Collar 41 Rotating shaft 42 Connecting bracket 43 Filling material 5 Drive drum 50 Drive drum G Gap r Earl R Curved portion W Track

Claims (4)

Two yokes and a magnet sandwiched so that both poles face the yoke side are provided, and the width direction end of the magnet is retracted from the width direction end on the side magnetically attached to the track of the yoke. A plurality of pairs of yokes,
A plurality of connecting means provided between two yokes that are adjacent to each other in the connecting direction, comprising two rotating shafts and connecting metal fittings attached to both ends thereof;
A first shaft hole is formed in which one end of one pivot shaft of the connecting means is inserted into one end of each yoke pair in the longitudinal direction and is inserted on both sides of each yoke pair. Bearings,
A shaft hole is formed which is inserted into the other end portion in the longitudinal direction of each yoke pair and into which the other end portion of the one rotation shaft of the connecting means disposed on both sides of each yoke pair is inserted. A second bearing,
A magnet type chain belt comprising a plurality of yoke pairs connected endlessly by the bearings and the connecting means. The magnet type chain belt according to claim 1, wherein a shape of an end portion in a width direction magnetically attached to the track of each of the yokes is formed in accordance with a surface shape of the track. 2. The magnetic chain belt according to claim 1, wherein a spacer made of a non-magnetic material is provided between the two yokes forming a pair, and a magnet is fitted through the central portion of the spacer. 2. The magnetic chain belt according to claim 1, wherein the coupling member provided between the pair of yokes has a recess or a hole that can mesh with the teeth of the sprocket.

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