Replaceable wear pad, as well as method for manufacturing wear pads for a crawler track

Abstract

A replaceable wear pad for a crawler track of a tracked vehicle includes base plates for fastening thereto wear pads in a detachable manner, the wear pad includes a tread and a bottom side lying opposite to the tread and facing the base plate, the wear pad containing at least one reinforcing element, and the reinforcing element being moulded-in by the wear pad material, the reinforcing element includes at least two holes and the wear pad includes cavities that run coaxially to the holes of the reinforcing element and, coming from the bottom side, end above the reinforcing element and at a distance to the same with the cavities serving the purpose of accommodating fastening devices which are fastened to the reinforcing element of the wear pad.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a crawler track with wear pads in perspective view.

FIG. 2 is a perspective illustration of a wear pad with a base plate of the crawler track.

FIG. 3 is a cross-section of an assembly of the wear pad with the base plate.

FIG. 4 a is the mandrel of a mould tool with reinforcing element fitted in position.

FIG. 4 b is a further embodiment of a mandrel of the mould tool.

FIG. 4 c is the mandrel in accordance with FIG. 4b, with elastic annular sleeve fitted in position.

FIG. 4 d is a further embodiment of a mandrel for an insert nut.

FIG. 5 an insert nut.

FIG. 6 is a partial view of the recesses in the projections of the wear pad.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an embodiment of a crawler track 2 that runs on replaceable wear pads 1. Such crawler tracks are required in the travel drive units of a tracked vehicle, for instance, a road construction machine. The wear pads 1 are fastened to base plates 4 in a detachable manner, with the base plates themselves being fastened to chain links 6 of the infinitely rotating crawler track 2. The crawler track 2 with its chain links 6 rotates around two deflection rollers 8 and 10, one of which is driven. Several support rollers 12 are arranged in the lower return side of the crawler track 2, which support the machine weight and run on the chain links.

FIG. 2 shows a perspective view of the wear pad 1 with the subjacent base plate 4 and two of the total number of four retaining screws 20 for fastening the replaceable wear pad 1 on the base plate 4.

The wear pad 1 preferably consists of an elastomeric material like, for instance, polyurethane, which is through-coloured with a light luminescent colour, preferably Signal Yellow, in accordance with one particularly preferred embodiment.

The wear pad 1 shows completely moulded-in reinforcing elements 18 that preferably run in longitudinal direction of the wear pad 1. In the embodiment, two such reinforcing elements 18 are arranged at a lateral distance to one another in the wear pad 1. The reinforcing elements 18 are provided with holes 22 close to their free ends, having a distance in longitudinal direction of the wear pads, by means of which fastening devices 26,28 of the wear pad can be fixed in the holes after manufacture of the wear pads 1.

The wear pads 1 have a tread 14 on their outer side, as well as a bottom side 16 facing the base plate 4.

Above the holes 22, cavities or recesses 30 extend in the direction of the tread 14 that serve the purpose of accommodating fastening devices 26,28. The recesses 30 run coaxially to the holes 22 of the reinforcing element 18. These recesses 30 are adapted to the fastening devices to be inserted. The fastening devices may consist of blind rivet nuts 26 or insert nuts 28, with the insert nuts 28 showing both an internal thread as well as an external thread. The fastening devices 26, 28 are suitable for accommodating retaining screws 20 that are suitable for screwing in from the bottom side 16 of the wear pad, as indicated in FIG. 2. For this purpose, the base plates 4 show suitable through-holes 32 which run coaxially to the fastening devices 28, 28 and the holes 22 of the wear pad 1. It is essential that the fastening devices 26, 28 rest immediately on the base plate 4 in the mounted condition of the wear pad 1.

In the embodiment, the two reinforcing elements 18 in the wear pad 1 run in projections 36, 38 that are parallel to one another and project from the bottom side 16 of the wear pad 1, leaving a space 40 between them. The space 40 between the projections 36, 38 co-operates with a central stud 42 of the base plate 4 in such a manner that the central stud 42 forms a seat for the space 40 between the projections 36, 38, and that the central stud 42 of the base plate 4 is capable of centering the wear pad 1 essentially without play on the crawler track 2. A narrow fit may be chosen between the central stud 42 and the space 40 so as to ensure that the wear pad 1 sits on the base plate 4 essentially without play.

The projections 36, 38 lie in channels 44, 46 on the base plate 4 and can rest in the said channels. The outer faces of the projections 36, 38 do, however, have sufficient play with the outer lateral faces of the channels 44, 46 so that the wear pad 1 is centred by the central stud 42 of the base plate 4 only. The projections 36, 38 extending in longitudinal direction of the wear pad 1 are interrupted by two recesses 48, 50 running in transverse direction that create a free space for screw heads of fastening devices which connect the base plate 4 with the chain links 6 through the through-holes 52. As can best be seen from FIG. 6, these fastening devices are therefore covered by the wear pad 1 in mounted condition and will not become clogged or damaged by road material.

As can be seen in FIG. 2, the strip-shaped reinforcing elements 18 run in a plane that is offset in a parallel manner in relation to the tread 14 in the area of the recesses 48, 50.

In longitudinal direction of the wear pad 1, the same projects vis-à-vis the base plate 4 on the outer side of the crawler track 2. Kerbs, for instance, are protected in this way against the metallic base plates 4, and on the other hand the base plates 4 are also protected against damage.

FIG. 3 shows the wear pad 1 mounted on the base plate 4 in a plane that passes through the axes of the holes 22. The recesses 30 of the wear pad 1 accommodate blind rivet nuts 26 which are firmly fastened to the reinforcing elements 18 in the holes 22 of the reinforcing elements 18 by shaping of an annular bead 56 that forms on account of the riveting operation. The blind rivet nuts 26 preferably rest on the base plate 4 with a bearing collar 27.

FIGS. 4 a to 4d show different possibilities of designing the recesses 30 for the purpose of accommodating fastening devices 26, 28. A part of the mould tool 60 can initially be seen in FIGS. 4a to 4d, with a mandrel 62, 64 or 66 respectively projecting from the said mould tool. With a wear pad 1 in accordance with FIG. 2, the mould tool 60 shows four such mandrels 62, 64, 66. The reinforcing elements 18 are fitted in position on the mandrels 62, 64, 66 with their holes 22, with the reinforcing elements 18 resting on an annular collar 70, the shape of which is adapted to the bearing collar 27 of the blind rivet nut 26 or the insert nut 28. In the embodiment of FIG. 4a, the mandrel 62 is of circular cylindrical shape.

In the embodiment of FIG. 4b, the mandrel 64 has a hexagonal cross-section and can be inserted in a hexagonally shaped hole 22 of the reinforcing element 18. The mandrel 64 is lengthened by, for instance, a cylindrical appendage 72 which extends beyond the length of a blind rivet nut 26 or an insert nut 28. This creates additional free space for the free end of a retaining screw 20. The appendage 72 may alternatively also show a different cross-sectional shape.

An annular sleeve 74 consisting of an elastic material like, for instance, foam rubber is additionally fitted in position in the embodiment shown in FIG. 4c, as compared to the embodiment shown in FIG. 4b. This elastic sleeve 74, which sits directly on the reinforcing element 18, forms a soft annular zone after completion of the wear pad 1, on that side of the reinforcing elements 18 that face the tread 14, in such a manner that the annular bead 56 of the blind rivet nut 26 that forms because of the blind riveting operation is not hindered in its deforming process.

Alternatively, it is also possible to rework the wear pad 1 and to undercut an annular groove for the annular bead 56 of a blind rivet nut 26 in the area behind the hole 22 when using, for instance, a cylindrical mandrel in accordance with FIG. 4a.

FIG. 5 shows the use of an insert nut 28 as fastening device. The insert nut 28 is provided with an external and an internal thread so that the insert nut 28 is suitable for screwing into the holes 22 of a reinforcing element 18 if the holes 22 are designed as threaded holes. Alternatively, the insert nut may show a self-cutting or self-tapping external thread that produces a thread in the holes 22 by itself when being screwed into the holes 22.

Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the apparatus without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims

1. A replaceable wear pad (1) for a crawler track (2) of a tracked vehicle, in particular for construction machinery, where the crawler track (2) shows several base plates (4) for the purpose of accommodating a wear pad (1), where the wear pad (1) is suitable for being fastened to a base plate (4) in a detachable manner,the wear pad (1) shows a tread (14), as well as a bottom side (16) lying opposite to the tread (14) and facing the base plate (4),the wear pad preferably contains at least one reinforcing element (18), andthe reinforcing element (18) is moulded-in by the wear pad material,

2. The wear pad in accordance with claim 1, characterized in that the reinforcing element (18) is flattened, at least in the area of the holes (22), preferably parallel to the tread (14).

3. The wear pad in accordance with claim 1, characterized in that the reinforcing element (18) and/or the wear pad (1) show an anti-twist protection for the fastening device (26, 28).

4. The wear pad in accordance with claim 1, characterized in that the holes (22) of the reinforcing element (18) and the cavities (30) of the wear pad (1) show a cross-sectional contour that is adapted to the outside contour of the fastening devices (26, 28).

5. The wear pad in accordance with claim 1, characterized in that the recesses (30) of the wear pad (1) show a cavity that extends beyond the length of the fastening devices (26, 28) to be inserted, the said cavity serving the purpose of accommodating the free end of a retaining screw (20) that interacts with the fastening device (26).

6. The wear pad in accordance with claim 1, characterized in that a bearing collar (27) of the fastening device (26, 28) rests against that side of the reinforcing element (18) that faces the base plate (4).

7. The wear pad in accordance with claim 6, characterized in that the bearing collar (27) of the fastening device (26, 28) terminates essentially flush with the bottom side (16) of the wear pad (1) and/or rests on the base plate (4) in mounted condition.

8. The wear pad in accordance with claim 1, characterized in that the reinforcing elements (18) run transversely to the moving direction of the wear pad (1) in operation.

9. The wear pad in accordance with claim 1, characterized in that the reinforcing elements (18) are made of a high-strength material, and preferably of metal.

10. The wear pad in accordance with claim 1, characterized in that the wear pad (1) shows projections (36, 38) on the bottom side (16) that run transversely to the moving direction, the said projections (36, 38) engaging with mutually adapted channels (44, 46) of the base plate (4).

11. The wear pad in accordance with claim 10, characterized in that the reinforcing elements (18) are integrated into the projections (36, 38).

12. The wear pad in accordance with claim 10, characterized in that the projections (36, 38) show at least two recesses (48, 50) in longitudinal direction, with the said recesses (48, 50) extending into the wear pads (1) and forming a space for fastening devices of the base plate (4) in mounted condition of the wear pad (1).

13. The wear pad in accordance with claim 1, characterized in that each of the reinforcing elements (18) integrated into the wear pads (1) consists of one piece and runs in at least two planes, namely in a plane close to the bottom side of the wear pad (1) in the area of the cavities (30) for the fastening devices, and in a plane removed into the interior of the wear pad (1) in the area of the recesses (48, 50) of the projections (36, 38).

14. The wear pad in accordance with claim 10, characterized in that the space (40) between the projections (36, 38) in longitudinal direction of the wear pad (1) accommodates, with narrow fit, a central stud (42) of the base plate (4) for the purpose of centering the wear pad (1) on the base plate (4).

15. The wear pad in accordance with claim 1, characterized in that the wear pad (1) projects vis-à-vis the base plate (4) at least towards the outer side of the crawler track (2).

16. The wear pad in accordance with claim 1, characterized in that the material of the wear pad (1) consists of an elastomer, and preferably of a polyurethane.

17. The wear pad in accordance with one claim 1, characterized in that the material of the wear pad (1) is through-coloured with a light luminescent colour, preferably Signal Yellow.

18. The wear pad in accordance with claim 1, characterized in that the fastening devices in the recesses of the wear pad (1) consist of blind rivet nuts (26).

19. The wear pad in accordance with claim 18, characterized in that the blind rivet nut (26) forms an annular bead (56) that is shaped towards the outside during the riveting operation, the said annular bead (56) resting immediately on that side of the reinforcing element (18) that faces the tread (14).

20. The wear pad in accordance with claim 1, characterized in that the holes in the reinforcing elements (18) are provided with a thread, and that the fastening devices in the recesses of the wear pad (1) consist of insert nuts (28) that are suitable for screwing into the thread of the holes (22) of the reinforcing element (18).

21. The crawler track for tracked vehicles, in particular for construction machinery, with several base plates (4) and with replaceable wear pads (1) that are suitable for bolting onto the base plates (4) in accordance with claim 1.

22. A method for manufacturing wear pads (1) for a crawler track (2) of a tracked vehicle, in particular for construction machinery, by moulding-in at least one reinforcing element (18) that preferably extends in longitudinal direction of the wear pad (1) in a mould tool (60),by holding the at least one reinforcing element (18) by projecting mandrels (62, 64, 66) of the mould tool (60), with the mandrels (62, 64, 66) passing at least partially through holes (22) provided in the reinforcing elements (18) while the reinforcing elements (18) are moulded-in,by creating cavities (30) with the aid of the projecting mandrels (62, 64, 66), the said cavities (30) being coaxial to the holes (22) of the reinforcing element (18) and serving as spacers for fastening devices (26, 28) to be mounted at a later stage, andby fastening, subsequent to moulding-in of the reinforcing elements (18), fastening devices (26) in the holes of the reinforcing elements (18) for completion of the wear pads (1).

23. The method in accordance with claim 22, characterized in that mandrels (62, 64, 66) with an annular collar (70) at the base are used, where the reinforcing elements (18) rest on said annular collar (70) during the moulding-in operation.

24. The method in accordance with claim 22, characterized in that mandrels (62, 64, 66) are used, the cross-sectional shape of which corresponds to the cross-sectional shape of the fastening devices (26, 28) to be inserted into the wear pads (1).

25. The method in accordance with claim 22, characterized in that mandrels (62, 64, 66) are used that are lengthened beyond the length of the fastening devices (26,28) to be inserted for the purpose of creating a cavity during moulding for the free ends of retaining screws (20) that interact with the fastening devices (26, 28).

26. The method in accordance with claim 22, characterized in that blind rivet nuts (26) are used as fastening devices in the recesses of the wear pad (1).

27. The method in accordance with claim 26, characterized in that a sleeve (74) consisting of elastic material is fitted in position on the mandrels prior to moulding-in of the reinforcing elements (18) that are held by the mandrels, with the said sleeve (74) resting against the mandrel (66) on the one hand and against the front end of the reinforcing element (18) on the other hand.

28. The method in accordance with claim 26, characterized in that prior to fastening the fastening devices (26), an undercut is produced with a suitable tool on that side of the reinforcing element (18) that faces away from the bottom side (16), the said undercut adjoining the reinforcing element (18) and widening the cavity (30) in a radial manner so that a cavity is formed which serves the purpose of accommodating an annular bead (56) that deforms towards the outside during the riveting operation of a blind rivet nut (26).

29. The method in accordance with claim 22, characterized in that insert nuts (28) are used as fastening devices in the holes (22) of the reinforcing elements (18).

30. The wear pad in accordance with claim 2, characterized in that the reinforcing element (18) and/or the wear pad (1) show an anti-twist protection for the fastening device (26, 28).

31. The wear pad in accordance with claim 11, characterized in that the projections (36, 38) show at least two recesses (48, 50) in longitudinal direction, with the said recesses (48, 50) extending into the wear pads (1) and forming a space for fastening devices of the base plate (4) in mounted condition of the wear pad (1).

32. The method in accordance with claim 23, characterized in that mandrels (62, 64, 66) are used, the cross-sectional shape of which corresponds to the cross-sectional shape of the fastening devices (26, 28) to be inserted into the wear pads (1).