The present invention is related to a tooth system for use in an earthmoving device, such as a dredging or mining device, comprising a tooth and an adapter onto which the tooth is mounted in a detachable fashion, the tooth comprising a

longitudinally extending tooth web, a longitudinally extending tooth base and a longitudinally extending tooth head at a distance from the tooth base, said tooth base and tooth head also extending generally transversely with respect to the tooth web, the adapter comprising an adapter base which is to be fixed onto the earthmoving device, such as onto the teeth bars of a draghead, and an adapter head, a longitudinally extending undercut cavity being defined between the adapter base and the adapter head, wherein the tooth base can be slidably fitted within the undercut cavity and wherein the adapter head can be slidably fitted between the tooth base and the tooth head for mounting or dismounting the tooth with respect to the front end of the adapter.

Such a tooth system is disclosed in the European patent publication EP 1 997

967 Al . This publication discloses a tooth system wherein the adapter and tooth are provided with least one pair of correspondingly shaped facing contact zones having a stepped configuration. The stepped layout of the facing contact zones represents a stable support for the tooth with respect to the adapter. The stepped contact zones represent separate areas for supporting the tooth, suitable for withstanding forces and bending moments exerted on the tooth.

A disadvantage of this tooth system, and similar prior art tooth systems, is that the lifetime of the tooth and/or the adapter is limited due to wear of the contact zones. Initially the tooth is snugly fitted into the cavity of the adapter. However, as a result of manufacturing tolerances of the parts and wear in the contact zones, a certain amount of play between de contact surfaces of the tooth and adapter may initially be present and/or will eventually occur. The amount of play increases in time. This ever increasing amount of play may result in even more wear of the contact zones of the adapter and/or tooth. Within a relatively short period of use the tooth and/or adapter needs to be repaired or even replaced. Especially in situations wherein the tooth system is used in submerged conditions, for instance when the tooth system is employed in an

earthmoving machine such as a dredging device, the short lifetime of the adapter and, especially, the tooth may result in considerable down time and associated operational costs.

It is an object of the invention to provide an improved tooth system wherein the above-mentioned and/or other disadvantages of the prior art have been reduced or even obviated.

It is a further object of the invention to provide a tooth system having a prolonged lifetime.

At least one of the objects is achieved in a tooth system for use in an

earthmoving device according to the preamble of claim, wherein the adapter comprises at least a first zone which faces at least a correspondingly shaped first zone of the tooth and at least a second zone which faces at least a corresponingly shaped second zone of the tooth, wherein the tooth and adapter are constructed and arranged so that in a first period of use the first zones of the adapter and tooth are contact zones and the second zones of the adapter and tooth are clearance zones and in a second period of use, after wear of the first contact zones, the second zones of the adapter and tooth are contact zones.

Due to this configuration of the tooth and adapter the second zones, once in the second period of use they have become contact zones, are able to at least partly take over the support function of the first zones. This results in the first zones to be less subjected to wear. The system can be used for a longer period of time before the effects of wear necessitates the system to be repaired, for instance by replacing the tooth. The lifetime of the system may therefore be prolonged.

A further advantage of the tooth system according to the invention may be that the dimensional tolerance needed for a proper support of the tooth in the adapter may be chosen generally larger than in the prior tooth systems. The requirements regarding the accuracy of the manufacturing process of the tooth and/or adapter may in other words be less strict than in existing tooth systems. For instance, in embodiments of the invention, manufacturing steps, such as polishing of the contact surfaces, may be simplified or are no longer needed. Furthermore, in embodiments of the invention, the adapter and/or tooth may therefore be made using relatively low cost production processes.

In an embodiment the first zones have a first contact surface area and the second zones have a second contact surface area, wherein the second contact surface area is greater than the first contact surface area. The second contact surface area may at least be twice the first contact surface area. This provides the advantage that the lifetime of the tooth system is significantly increased.

In an embodiment the first zones and the second zones of the adapter and tooth are at least partially positioned one above the other. This provides the advantages that a relatively large contact surface area can be created in a relatively small volume.

In an embodiment of the invention the adapter and tooth are constructed and arranged so that in the second period of use first zones of the adapter and tooth become clearance zones as a result of wear.

In an embodiment of the invention the adapter and tooth are constructed and arranged so that in the second period of use first zones of the adapter and tooth remain contact zones. This means that the second zones may take over a part of the support function of the first zones so that the forces on the tooth and adapter may be distributed over a larger area, resulting in a longer lifetime. Furthermore, since initially only the first zones are contact zones and the second zones are clearance zones, the accuracy of the manufacturing process may be low relative to the embodiment wherein both the first zones and the second zones need to be contact zones right from the beginning.

In an embodiment of the invention the first zones are arranged in the upper part of the tooth and the adapter and the second zones are arranged in the lower part of the tooth and the adapter. In this embodiment the zones in the upper part of the tooth and adapter would generally be the zones that need to be repaired first. Generally the upper zones of the tooth and/or adapter can be accessed more easily than the other parts of tooth and, especially, the adapter.

In an embodiment the first zones comprise at least one surface of the tooth head, the surface facing downward, and at least one surface of the adapter head, the surface facing upward.

In an embodiment of the invention the second zones comprise at least one surface of the adapter base facing upward and at least one surface of the tooth base facing downward.

In an embodiment the tooth head comprises tooth head flanges extending transversely on opposite sides of the tooth web, the tooth base comprises tooth base flanges extending transversely on opposite sides of the tooth web, and the distance between the first and second zones of the tooth head flanges and the tooth base flanges essentially corresponds to the distance between the bottom surface of the undercut cavity and the top surface of the adapter head. In this way the tooth may be firmly supported by the adapter.

In an embodiment of the tooth system a first distance between the first and second zones of the tooth is substantially different from a second distance between the first and second zones of the adapter. The first and second distances are measured in a direction substantially perpendicular to the first and second zones. The term

substantially different is used to indicate that there may be a difference of 0.1 - 5 mm. The first distance may be larger than the second distance, or vice versa.

In an embodiment the adapter head comprises opposite transversal adapter flanges which define a slit at their facing edges and which delimit the undercut cavity, the web of the tooth extending through the slit and the tooth head facing the adapter flanges. The tooth base may comprise tooth base flanges extending on opposite sides of the tooth web, each tooth base flange facing a corresponding adapter flange.

In an embodiment the tooth comprises a front cover which extends transversely with respect to the tooth head and the tooth base and which, in use, faces the front end of the adapter. Preferably, the front cover of the tooth abuts the front end of the adapter so as to avoid clenching of the tooth with respect to the adapter which would prevent replacement of the tooth. The tooth head and front cover may be connected to each other, for instance at a sharp angle. The combined effect of the interconnected tooth head and front cover provides an advantageous shielding of the areas of the adapter which would otherwise be prone to the abrasive influences of the excavated (or dredged) materials. Furthermore, the interconnected tooth head and front cover provide an additional stabilizing effect with respect to the correspondingly shaped adapter, the front of which is snugly surrounded by said combined tooth head and front cover.

In an embodiment of the invention a locking construction is provided which comprises a locking member positioned at an end of the undercut cavity of the adapter, and a locking part at the tooth web facing the locking member. The locking member and the front cover may be located at opposite ends of the adapter.

In an embodiment the undercut cavity of the adapter is tapered from a relatively wide front end to a relatively narrow back end, the base member of the tooth having an essentially similar taper. According to another aspect of the invention a tooth system according to the preamble of claim 1 is provided wherein at least one wear part, for instance a wear plate, is arranged between an adaptor zone and a tooth zone. The wear part may be arranged loosely between the bottom of the cavity of the adaptor and a lower part of the tooth or loosely between the aft side of the front cover of the tooth and the front end of the adapter or loosely between the tooth head and the adapter head which makes it easy to exchange the part, when needed, for a new wear part. In other embodiments the wear part is mounted to the adapter, for instance using bolts. The wear part may extend over the full length and width of zones, not being delimited by individual sections of the adapter or the tooth.

The wear part may have a thickness corresponding to the initial amount of play between the zones of the tooth and adaptor so that play is minimized.

Further details, characteristics, effects and advantages of the invention will become apparent from the following description of several embodiments thereof. In the description reference is made to the annexed figures.

Figure 1 shows a side view in perspective of a first embodiment of the tooth system according to the invention.

Figure 2 shows a rear view in perspective of the first embodiment.

Figure 3 shows a further side view of the first embodiment.

Figure 4 shows a front view of the first embodiment.

Figure 5 shows a side-aft view of an embodiment of the tooth according to the present invention.

Figure 6 shows a bottom-aft view of the embodiment of the tooth according to figure 5;

Figure 7 shows a bottom- front view of the embodiment of the tooth according to figures 5-6;

Figure 8 shows a further side-top view of the tooth according to figures 5-7; Figure 9 shows a rear view of the tooth according to figures 5-8;

Figure 10 shows a side view of the tooth according to figures 5-9;

Figure 11 shows a side-rear view of an embodiment of the adapter of the tooth system according to the invention;

Figure 12 shows a side-front view of the embodiment of figure 11;

Figure 13 shows a side-bottom view of the embodiment of figures 11-12; Figure 14 shows a rear view of the embodiment of figure 11-13;

Figure 15 shows a front view of the embodiment of figures 11-14;

Figure 16 schematically shows a connected adapter and tooth, in a first stage;

Figure 17 shows the connected adapter and tooth, in a second stage;

Figure 18 shows a view in perspective from below of a draghead provided with an embodiment of the tooth system according to the present invention.

The embodiment of the tooth system 1 according to the invention, as shown in the figures, especially figures 5-10, comprises a tooth 4 that can be releasably connected to an adapter 3. The tooth 4 comprises a tooth base 10, as shown in figures 5 and 9, a tooth head 12 and a tooth web 11 which extends between the base 10 and the head 12. The tooth 4 further comprises an excavating element 13, extending from the tooth head 12. The excavating element 13 may be provided with one or more cutting edges 9. The excavating element 13 may further comprise a plurality of reinforcement ribs 20 extending from the excavating element 13 to the tooth head 12, reinforcing the excavating element 13. As shown in the figures, the tooth head 12 is located opposite the tooth base 10, at a predefined distance. Referring to figure 10, the tooth 4 further comprises a front cover 7, located at the front end of the tooth and extending in a lateral direction (generally transversely to the longitudinal direction defined by the tooth web 11) between tooth head 12 and tooth base 10. In use the front cover 7 comprises two inner walls 18, 19 which face a front end 40 of the adapter 3. In the embodiments shown in the figures the tooth head 12 and the front cover 7 are connected to each other, for instance at a sharp angle.

The base 10 of the tooth 4 comprises a plurality of flanges extending generally transversely to the tooth web 11. At the front end of the tooth relatively wide flanges 14 and 15 are provided, that extend sideways from the tooth web 11, while at the rear end of the tooth the tooth base 10 comprises flanges 25 and 26. The tooth head 12 also comprises a couple of flanges 16,17, extending sideways from the tooth web 11. In the embodiment shown in the figures the flanges 14-17 extend generally perpendicularly to the tooth web 11. In other embodiments one or more of the flanges 14-17 may extend at an angle relative to the tooth web 11.

The adapter 3 comprises an adapter base 30, an adapter head 31 and two opposite upstanding walls 34,35 between the adapter base 30 and adapter head 31. Reference is made to Fig.'s 11 - 15. The adapter head 31 comprises facing adapter flanges 36,37. The adapter base 30, upstanding walls 34,35 and adapter head 31 with adapter flanges 36,37 of the walls 34,35 define an elongate undercut cavity 33 that extends in a generally longitudinal direction. The cavity 33 opens out by means of slit 38 at the position of the adapter flanges 36,37.

As shown in figures 1-15, the tooth base 10 of the tooth 4 can be slid into and out the undercut cavity 33 of the adapter 3. At the same time, the tooth web 11 of the tooth 4 can be slid in and out the slit 38 so that it can be accommodated therein.

Furthermore, the undercut cavity 33 widens out at the front part of the adapter 3 into a pair of lower indentations or slots 45,46 into which respective bottom flanges 14,15 can be accommodated. Similarly, a pair of upper indentations or slots 47, 48 may be provided in the adapter head 31 of the adapter 3. Into the indentations or slots 47,48 respective upper flanges 16,17 of the tooth head 12 of the tooth 4 can be

accommodated, partly or entirely. In other embodiments, not specifically shown in the figures, the upper slots 47,48 are not present. In these embodiments the upper flanges 16, 17 of the tooth head may rests on the upper (flat) surface of the adapter head 31.

As the tooth 4 comprises a front cover 7, opposite the front end 40 of the adapter 3, the sliding motion of the tooth 4 with respect to the adapter 3 is limited as soon as the front end 40 of the adapter 3 and the front cover 7 of the tooth 4 come into contact. With the aim of further improving the locking of the tooth 4 with respect to the adapter 3, the front end 40 of the adapter 3 comprises the above-mentioned indentations or slots 45,46, and the facing surface (inner walls 18, 19) of the front cover 7 and the tooth base 10 comprises protrusions or flanges 14,15 which are accommodated within the indentations or slots In a similar way the upper flanges 16,17 of the tooth head 12 may be accommodated in the slots or indentations 47,48 in the adapter head 31.

Another function of the tooth head 12 and the front cover 7 is that they may protect the adapter 3 with respect to the abrasive action of the materials which are being cut by the tooth system in question.

Referring to figures 1 and 2, the rear end 41 of the adapter 3 opposite the front end 40 is provided with a locking construction 50 for locking the tooth 4 with respect to the adapter 3. The locking construction 50 comprises a locking element 51 connected to the adapter 3, as well as a hook 22 forming part of the tooth 4 (see for instance figure 5). The locking element may comprise a pin 52 that can be removably positioned behind the hook 22 so as to lock the tooth relative to the adapter.

As mentioned before, the tooth 4 has been provided with a tooth head 12. The tooth head 12 is connected to the front cover 7 and to the tooth web 11. The tooth head 12 comprises two tooth head fianges 16, 17, extending in opposite lateral directions relative to the tooth web 11. In use, the tooth head flanges 16, 17 each bear on a corresponding adapter side wall 34,35, more specifically the indentations 47,48 provided therein. Similarly, the tooth base 10 is connected to the front cover 7 and the tooth web 11 and comprises two tooth base flanges 14,15, extending in opposite lateral directions. In the embodiments shown in the figures the upper flanges 16,17 and lower flanges 14,15 are essentially parallel.

The internal cavity 33 of the adapter 3 may have a generally tapering shape, running from a relatively wide cross-section at the front end 40 towards a relatively small cross-section at the back end 41. Similarly, the tooth base 10 may have a tapering shape so as to snugly fit within said internal cavity 33 of the adapter 3.

The tooth system according to the invention may be mounted at an earthmoving device 59. Figure 18 shows an example wherein the tooth system is connected to a draghead. Generally the draghead comprises a suction chamber housing 60 having a suction opening 61 and connected to the suction mouth 62 which is to be connected to a suction tube leading to the bin of a dredging vessel (not shown). Furthermore, a pressure conduit 63 is provided for supplying a number of jet nozzles 64 with pressurized water used in the cutting process. The adapters 3 of the tooth system 1 according to the invention are mounted on the teeth bars in the suction chamber housing 60 near the suction opening 61, whereby the teeth 4 are positioned in such a way that they can exert a cutting action on the bottom of a body of water while the draghead is dragged (to the right in the figures) over said bottom.

Once the tooth 4 of the tooth system 1 is slid into the adapter 3 and locked by means of the locking construction 50, the tooth system is ready for use. In use, for instance during dredging operations, the tooth 4 is firmly held inside the adapter. As result of the continuous movements of the tooth 4 relative to the adapter 3, the tooth 4 and/or the adapter 3 will suffer from wear, especially at those parts where the tooth 4 is in contact with the adapter 3. The adapter and tooth initially (in a first period of use) make contact in a number of first zones, while the adapter and tooth remain free (i.e. they are not in contact) in number of second zones. Referring to the figures, especially figures 6, 12, 16 and 17, the zones that are in contact (herein also referred to as contact surfaces or contact zones) are located both at the upper part and lower part of the tooth 4 and adapter 3. Figure 6 shows the first zones denoted by (A) of the tooth 4 are in contact with the adapter. The first zones (A) are present at the lower surfaces of the left flange 16 and the right flange 17 of the tooth head 12 (only the zone at the right flange 17 is shown in figure 12). The first zones (A) of the tooth are in contact with corresponding first zones of the adapter. Referring to figure 12, the first (adapter) zones that are in contact with the first zones (A) of the tooth are zones (D), situated at the upper surface of the indentations 47,48 in the adapter head 31. Also see Fig. 16, reference A, D.

Referring to figure 6, also first zone (B) of the tooth 4, i.e. the bottom surface of the tooth base 10, may be in contact with a corresponding first zone of the adapter 3. Referring to figure 17, in some embodiments of the invention first zone (B) of the tooth 4 is in direct contact with first zone E (cf. figure 12), i.e. the bottom surface of the cavity 33 of the adapter 3. In other embodiments, for instance shown in figure 16, first zone (B) of the tooth 4 is only indirectly in contact with first zone (E) of the adapter 3, since a so-called wear plate 70 is arranged between the lower surface of the tooth base 10 and the upper surface of the adapter base 30 (i.e. the bottom surface of the cavity 33), or at least between some of the first zones (A, B) of the tooth 4 and the first zones (D, E) of the adapter 3. The wear plate may be mounted by means of bolts or similar attachment means. This wear plate protects primarily the adapter base from wear, and can be easily replaced in case the plate has been worn down.

In the above-mentioned first period of use the adapter 3 and tooth 4 make contact in the first zones and therefore are locally subjected to wear. In the second zones, for instance second zone (C, figure 6) of the tooth 4 on the flanges 14,15 of the tooth base 10 and second zone (F, figure 12) of the adapter 3 at the front end of the adapter base 30, initially essentially no contact is made. The second zones wherein essentially no contact is made are herein also referred to as clearance surfaces of clearance zones. In practice the clearance 90 between the above-mentioned second zone (C) on the tooth base 10 and second zone (F) at the adapter base initially ranges between 0.1 and 2 mm. Due to wear the clearance will be diminished in the first period of use until the zones come in contact with each other (i.e. zero clearance). In the course of time the first zones will show an ever increasing wear. Due to the specific design of the tooth 4 and adapter 3 the wear at positions in the first zones will result in the clearance between the second zones of the tooth and adapter to be diminished. Eventually also the second zone (C) of the tooth 4 will be in contact with the second zone (F) of the adapter 3. From that moment in time, i.e. in a second period of use following the above-mentioned first period of use, the adapter 3 and tooth 4 are in contact not only in first zones but also in the second zones of the tooth 3 and the adapter 4. Thus the second zones may partly take over the supporting function of the first zones, resulting in a wear reduction at the locations of the first zones. In practice this means that the service intervals, i.e. the time intervals between subsequent repair or replacement actions, can become longer. Also the lifetime of the tooth and/or the adapted may be prolonged.

Due to tolerances of the manufacturing process a situation may occur that after mounting of the tooth 4 in adapter 3 the second surface C of the lower flanges 14, 15 of tooth 4 directly bears on the second surface F of the indentations 45, 46 of the adapter 3 and that there is play between the tooth head flanges 16, 17 and the corresponding adapter side walls 34, 35, more specifically the indentations 47, 48 provided therein. In such a situation the intention and advantage of the invention remains, having a first set of contact zones at the bottom side of the tooth base 10 of the tooth 4 and the bottom of indentations 45, 46 and/or the undercut cavity 33 of the adapter and a second set of contact zones between the tooth head 12 and the adapter head 31.

As can be seen in Fig.'s 6 and 12, the second contact surface area formed by the second zones is greater than the first contact surface area formed by the first zones. The second contact surface area may at least be twice the first contact surface area, or may even be at least three times the first contact surface area.

With reference to the figures it can be seen that in the second period of use, after wear of the first contact zones A, D, second zones B and C together with E and F will form contact zones, possibly together with the first contact zones A and D. In the second period of use, the total contact surface area is thus significantly increased with respect to the first period of use. This provides the advantage that the lifetime of the tooth system is significantly increased. Furthermore the first zones and the second zones of the adapter and tooth are at least partially positioned one above the other. As can be seen in the figures, for instance Fig.'s 6 and 12, the first zones and the second zones are at least partially provided at different relative heights with respect to each other, the height being in a direction substantially perpendicular to the first and second zones. The first zones are provided above the second zones, such that the first zones at least partially overlap the second zones. This provides the advantages that a relatively large contact surface area can be created in a relatively small volume.

Although the invention has been described with reference to specific embodiments thereof, it will be appreciated that the invention is not limited to these embodiments and that changes and modifications to the device described herein may be made without departing from the scope of the invention.