GB2290758A

GB2290758A - Cap assembly for refuse compaction vehicle wheel

Info

Publication number: GB2290758A
Application number: GB9512613A
Authority: GB
Inventors: Michael Ketting; Wilfried Batke; Karl-Friedrich Fischer; Mathias Woydt
Original assignee: Intertractor AG
Current assignee: Intertractor AG
Priority date: 1994-06-27
Filing date: 1995-06-21
Publication date: 1996-01-10
Anticipated expiration: 2015-06-21
Also published as: FR2721540A1; GB9512613D0; IT1275293B; FR2721540B1; ITMI951146A1; DE4422318A1; GB2290758B; DE4422318C2; ITMI951146A0

Description

2290758 A cap assembly for a cam of a wheel of a refuse compaction vehicle

The present invention relates to a cap assembly for a cam of a wheel of a refuse compaction vehicle. The wheels of refuse compaction vehicles comprise radially diverging, inherently stable cams disposed over their circumference which are laterally spaced from one another. Each cam consists of a supporting part which is disposed fixedly to a wheel and a shoe which is detachably mounted thereon, the supporting part and the shoe complementing one another to form a body roughly in the shape of a truncated pyramid. The supporting part comprises a radially converging, polygonal cone tapering to its free end, and the shoe has an insertion aperture adapted to receive and fit over the polygonal cone of the supporting part.

Such a design is known for example from DE 35 40 183 C2. In the prior art the supportinZ part and the shoe are made of steel, and the attachment of the parts to one another is performed for example by means of dowel pins, which are driven through holes or apertures in the shoe and the supporting part. In such previously known designs the shoes are subject to relatively high wear during the operational use of the vehicle for the purpose of refuse compaction. Consequently, the shoes have to be changed frequently which has proved to be a disadvantage.

Proceeding from such prior art, an aim of the present invention is to provide a refuse compaction vehicle of the given type, in which a longer service life is achieved without requiring the shoes to be changed.

2 Accordingly, the present invention provides a cap assembly for a cam of a wheel of a refuse compaction vehicle, said cap assembly comprising a shoe, which is substantially frusto-pyramidal in shape and which has an insertion aperture adapted for fitting onto a supporting part, and a wearing cap which is mounted on the truncated end of the shoe.

In one embodiment the wearing cap is reverse drawn onto the shoe.

In another embodiment the wearing cap is detachably mounted to the truncated end of the shoe.

With such constructions it is possible to form the actual wearing cap from a different, highly abrasion-proof, material; the result of which is that longer service lives are achieved and the necessity to change the cap assembly or wearing cap is less frequent.

In the first-mentioned embodiment the wearing cap is reverse drawn onto the shoe, which cap can be attached to the shoe in a suitable manner. In the second-mentioned embodiment, one part, preferably the upper part, of the shoe, is substituted by a wearing cap of the same or similar shape, with the shape of the wearing cap preferably corresponding to the shape of the outer contour of the shoe. In addition, first radii are preferably. constructed on the end of the wearing cap lying to the rear in the insertion direction, which first radii represent a reserve for wear, and second radii are also preferably provided at the interface between the end face of the wearing cap and the laterally sloping faces, which second radii ensure improved floor transition (action of force and compaction).

3 With regard to the adaptation of the wearing cap to the shape and contour of the compactor shoe, the geometric contour of the inner sides of the wearing cap, that is the contour of the sides of the wearing cap which are attached to the compactor shoe, is selected so that it corresponds to the outer shape or contour of the compactor shoe situated beneath it, and can be fitted, i.e. slipped on, such that the mode of operation of the shoe and the wearing cap in combined effect is ensured.

With a wearing cap which forms the truncated end of the cam, it is possible to attach the wearing cap to the end face of the shoe by mechanical means, for example by dovetail guides or the like. It is also possible to constrtct the wearing cap and the corresponding end face of the shoe with flat bearing faces, with the faces then being attached to one another in a suitable manner, for example by soldering, plasma spraying or gluing. It is within the scope of the invention preferably to design the matching shape between the wearing cap and shoe so that it meets the joint-related and/or technological requirements for mechanical and preferably nonmechanical attachment of the wearing cap to the shoe. With regard to non-mechanical attachment, the matching shape is preferably designed so that it satisfies the requirements for soldering, plasma spraying or gluing for the connection of the parts.

It is also preferred that the wearing cap is made of quenched and subsequently tempered steel.

However, it is particularly preferred that the wearing cap is made from a hard metal material, fibre-reinforced material, ceramicsceramics composite material and/or engineering or advanced ceramics.

Alternatively, the wearing cap can be made from abrasionproof sintered material on an iron base. Preferably, the 4 sintered material is a wear-resistant outer protective layer.

The wearing cap can also be formed of zirconium oxide (e.g. Zr02) 1 zirconium oxide compounds or high-strength, stabilised or partially stabilised, zirconium oxides on a base of non-oxide ceramics.

Preferably, the non-oxide ceramics comprises silicon nitride (S'3N4) More preferably, the silicon nitride includes less than 15 per cent by weight of sinter additive.

Preferably, the material of the wearing cap is selected to exhibit subcritical crack growth under normal operational loads and has a fracture toughness (K,.) of at least 5 MPa Vm.

In this case the strength and toughness is set at such a value by the use and metering of suitable additives, whereby in particular the homogeneity of the material is ensured and the dispersion of the material characteristic values, in particular the strength, is determined by a Weibull Modulus m of greater than 10, preferably greater than 20.

The present invention extends to the use of the above given materials for the manufacture of the shoes. By the manufacture of the shoes from such suitable materials a considerable reduction in wear of the shoes can also be achieved, resulting in a lower changing frequency of the shoes.

The present invention also provides a cam for a refuse compaction vehicle, which cam comprises a cap assembly as described above in combination with a supporting part, which part is in use fixedly mounted to a wheel of a refuse compaction vehicle, said supporting part including a polygonal conical portion on which the cap assembly is detachably mountable.

The present invention further provies a refuse compaction vehicle, the wheels of which comprise cams disposed over the circumference and configured so as to be laterally spaced from one another, each cam consisting of a supporting part which includes a polygonal conical portion and which is disposed fixedly to a wheel, and a cap assembly which comprises a shoe having an insertion aperture adapted to fit the conical portion of the supporting part and a wearing cap mounted on the truncated end of the shoe, wherein the cap assembly is detachably mounted on the supporting part and the supporting part and the cap assembly complement one another to form a body substantially frusto-pyramidal in shape.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:

Figure 1 shows a side view of a cap assembly in accordance with a first embodiment of the present invention; Figures 2 and 3 show side and front views of a cap assembly in accordance with a second embodiment of the present invention; and Figures 4 and 5 show side and front views, in partial section, of a cap assembly in accordance with a third embodiment of the present invention.

Figure 1 shows a cap assembly for a cam of a refuse compaction vehicle in accordance with a first embodiment of the present invention. The cap assembly comprises a shoe 6 and a wearing cap 1 which is reverse drawn onto the shoe 6 6, with the inner contour 5 of the wearing cap 1 being adapted to the outer contour of the shoe 6, so that a close seat is achieved.

Cap assemblies in accordance with second and third embodiments of the present invention, as shown in Figures 2 to 5, differ from the cap assembly in accordance with the first embodiment of the present invention in that the upper part of the shoe 6 is substituted by a wearing cap 2, the shape of which can correspond to the normal shape of the outer contour of the shoe 6. The wearing cap 2 is preferably provided at the interfacial region of the wearing cap 2 to the shoe 6 with first radii which represent a reserve for abrasion, and at the transition of the end face to the lateral faces of the wearing cap 2 with second radii 4 which are intended to produce improved floor transition (action of force and compaction).

In -the cap assembly in accordance with the second embodiment of the present invention as shown in Figures 2 and 3 the end face of the shoe 6 is flat, as is the inner f ace of the wearing cap 2 abutting it, so that in the region 7 a smooth bearing f ace is achieved therebetween. In the region of this bearing face an appropriate attachment can be achieved by soldering, plasma spraying or gluing.

In the cap assembly in accordance with the third embodiment of the present invention as shown in Figures 4 and 5 a mechanical cramping of the wearing cap 2 is achieved in the region of the interface 7 so that when the wearing cap 2 is connected to the shoe 6 in the region of the contact face, e.g. by soldering, plasma spraying or gluing, with the proper use of this structural unit additional load bearing is achieved by a cross-shaped projection provided at the end face of the shoe 6, which projection engagingly fits 7 into a corresponding cross-shaped recess at the underside of the wearing cap 2.

The invention is not restricted to the exemplified embodiments, and it will be understood that it may be varied in many different ways within the scope of the invention.

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Claims

1 A cap assembly for a cam of a wheel of a refuse compaction vehicle, said cap assembly comprising a shoe, which is substantially frusto- pyramidal in shape and which has an insertion aperture adapted for fitting onto a supporting part, and a wearing cap which is mounted on the truncated end of the shoe.

2. A cap assembly according to claim 1, wherein the wearing cap is reverse drawn onto the shoe.

3. A cap assembly according to Claim 1, wherein the wearing cap is detachably mounted to the truncated end of the shoe.

4. A cap assembly according to Claim 2 or 3, wherein the wearing cap is formed of quenched and tempered steel.

5. A cap assembly according to Claim 1, 2 or 3, wherein the wearing cap is formed of a hard metal material, fibrereinforced material, ceramicsceramics comDosite material and/or engineering or advanced ceramics.

6. A cap assembly according to Claim 1, 2 or 3, wherein the wearing cap is made from a sintered material on an iron base.

7. A cap assembly according to Claim 6, wherein the sintered material is a wear-resistant outer protective layer.

8. A cap assembly according to claim 6 or 7, wherein the iron base includes ferrochromium.

9 9. A cap assembly according to claims 1, 2 or 3, wherein the wearing cap is formed of zirconium oxide, zirconium oxide compounds or high-strength, stabilised or partially stabilised, zirconium oxides on a base of nonoxide ceramics.

10. A cap assembly according to claim 9, wherein the nonoxide ceramics base comprises silicon nitride.

11. A cap assembly according to claim 10, wherein the silicon nitride includes less than 15 per cent by weight of sinter additive.

12. A cap assembly according to any one of claims 1 to 11, wherein the material of the wearing cap is selected to exhibit subcritical crack growth under normal operational loads.

13. A cap assembly according to any one of claims 1 to 12, wherein the material of the wearing cap has a fracture toughness (KIc) of at least 5 MPaVm.

14. A cap assembly according to any any one of claims 1 to 13, wherein the shoe is formed of a hard metal material, fibre-reinforced material, ceramics-ceramics composite material and/or engineering or advanced ceramics.

15. A cap assembly according to any one of claims 1 to 13, wherein the shoe is made from a sintered material on an iron base.

16. A cap assembly according to claim 15, wherein the sintered material is a wear-resistant outer protective layer.

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17. A cap assembly according to claim 15 or 16, wherein the iron base includes ferrochromium.

18. A cap assembly according to any one of claims 1 to 13, wherein the shoe is formed of zirconium oxide, zirconium oxide compounds or highstrength, stabilised or partially stabilised, zirconium oxides on a base of non-oxide ceramics.

19. A cap assembly according to claim 18, wherein the nonoxide ceramics base comprises silicon nitride.

20. A cap assembly according to claim 19, wherein the silicon nitride includes less than 15 per cent by weight of sinter additive.

21. A cap assembly according to any one of claims 14 to 20, wherein the material of the shoe is selected to exhibit subcritical crack growth under normal operational loads.

22. A cap assembly according to any one of claims 14 to 21, wherein the material of the shoe has a fracture toughness (K,,) of at least 5 MPa Vm.

23. A cap assembly substantially as hereinbefore described with reference to Figure 1, Figures 2 and 3, or Figures 4 and 5 of the accompanying drawings.

24. A cap assembly according to any one of claims 1 to 23 in combination with a supporting part, which part is in use fixedly mounted to a wheel of a refuse compaction vehicle, said supporting part including a polygonal conical portion on which the cap assembly is detachably mountable.

25. A wheel of a refuse compaction vehicle incorporating a cap assembly according to any one of claims 1 to 23.

26. A refuse compaction vehicle having a wheel incorporating a cap assembly according to any one of claims 1 to 23.

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27. A refuse compaction vehicle, the wheels of which comprise cams disposed over the circumference and configured so as to be laterally spaced from one another, each cam consisting of a supporting part which includes a polygonal conical portion and which is disposed fixedly to a wheel, and a cap assembly which comprises a shoe having an insertion aperture adapted to f it the conical portion of the supporting part and a wearing cap mounted on the truncated end of the shoe, wherein the cap assembly is detachably mounted on the supporting part and the supporting part and the cap assembly complement one another to form a body substantially frusto-pyramidal in shape.

28. A refuse compaction vehicle according to claim 27, wherein the wearing cap is reverse drawn onto the shoe.

29. A refuse compaction vehicle according to Claim 27, wherein the wearing cap is detachably mounted to the truncated end of the shoe.