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Title:
PROCESS AND SYSTEM FOR REBUILDING CRAWLER SURFACE PAD
Document Type and Number:
WIPO Patent Application WO/2011/093792
Kind Code:
A1
Abstract:
A process for rebuilding a damaged crawler surface pad (125) of a crawler element (115) in a crawler loop (110) of a tractor crawler. The crawler surface pad (125) comprises a first pad layer (130) that is affixed to a base plate (135), to form a portion of the crawler loop (110). The process comprises steps of demounting the damaged crawler surface pad (125) selectively from the crawler loop (110), reconditioning the damaged crawler surface pad (125) and mounting it back onto the crawler loop (110), without causing a downtime for the tractor crawler, during the step of reconditioning. The process also provides for serviceability and safety tests for the crawler surface pad (125), after the steps of reconditioning and rebuilding. The damaged first pad layer (130) can be salvaged and recycled.

Inventors:
LEE POH LAI (SG)
Application Number:
PCT/SG2010/000028
Publication Date:
August 04, 2011
Filing Date:
January 29, 2010
Export Citation:
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Assignee:
GEWINNEN POLYMERS PTE LTD (SG)
LEE POH LAI (SG)
International Classes:
B62D55/32; B23P6/04
Foreign References:
JP2005096583A2005-04-14
US5388900A1995-02-14
US4185877A1980-01-29
US4448459A1984-05-15
US6296329B12001-10-02
Attorney, Agent or Firm:
CHONG, Y. F. (PSA Building, Singapore 4, SG)
Download PDF:
Claims:
CLAIMS

1. A rebuilding process for a crawler surface pad (125) of a crawler element (115) in a crawler loop (110) of a tractor crawler, the process comprising the following steps: demounting at least the crawler surface pad (125) selectively from the crawler loop (110), the crawler surface pad (125) comprising a first pad layer (130) that is affixed to a base plate (135) to form a portion of the crawler loop (110); reconditioning the at least the crawler surface pad (125) after the step of demounting; and mounting the at least the crawler surface pad (125) onto the crawler loop (110) after the step of reconditioning, without causing a downtime for the tractor crawler while the step of reconditioning.

2. A process as claimed in Claim 1 wherein the step of reconditioning comprises the following steps: releasing the first pad layer (130) from the base plate (135) by a releasing means; cleaning the base plate (135) by a cleaning means for removing residues particularly from the first pad layer (130); repairing damages if available on the base plate (135) by a repairing means, the damages being such as cracks, holes and dents; smoothening the base plate (135) optionally, by a smoothening means; applying an adhesive as an adhesive layer onto at least a portion of the base plate (135) by an applicator means; molding the base plate (135) by a compound in a compression molding means, for forming a second pad layer (150), that is affixed to the base plate (135) by the adhesive layer; curing the second pad layer (150) in a curing means, the curing means being maintained at a predetermined ambient, the aforesaid steps being followed in the given sequence; inspecting the base plate (135) for the damages, after any of the steps, by an inspecting means; and inspecting the second pad layer (150) after the curing step, by the inspecting means.

3. A process as claimed in Claim 2, wherein the releasing means, at least partially, is one of the following: heat, a chemical composition, a mechanical means.

4. A process as claimed in Claim 2 wherein the cleaning means is a sandblasting means.

5. A process as claimed in Claim 2 wherein the repairing means is a welding means, when the base plate (135) is metallic.

6. A process as claimed in Claim 2 wherein the repairing means is a forging means, when the base plate (135) is metallic.

7. A process as claimed in Claim 2 wherein the smoothening means is the sandblasting means.

8. A process as claimed in Claim 2 further comprising a step of applying a primer onto the at least a portion of the base plate (135) before the step of applying the adhesive, unless the adhesive itself functions also as the primer.

9. A process as claimed in Claim 2, wherein the compound is a rubber material.

10. A process as claimed in Claim 9, wherein the rubber material, is composed of :

approximately 61% of natural rubber,

approximately 30% of polybutadiene rubber, and

approximately 9% of carbon black and accelerator, the composition being by weight.

11. A process as claimed in Claim 2, wherein the predetermined ambient is defined by:

2 hours of curing time,

150 degrees centigrade of temperature, and

100 to 200 PSI of pressure.

12. A process as claimed in Claim 2, wherein the predetermined ambient is defined by:

3 hours of curing time,

160 degrees centigrade of temperature, and

100 to 200 PSI of pressure.

13. A process claimed in Claim 2 wherein a formulation of the compound and the predetermined ambient are optimised for achieving various properties of the second pad layer (150), the properties being related to tensile strength, specific gravity and various mechanical properties including elongation at break.

14. A process as claimed in Claim 2 wherein the step of inspecting includes checking a thickness of the base plate (135) to confirm it is within a required specification and is suitable for reconditioning.

15. A process as claimed in Claim 2 wherein the step of inspecting includes visual assessment.

16. A process as claimed in Claim 2, further comprising a step of checking quality of the crawler surface pad (125), by a testing means, after the step of curing.

17. A process as claimed in Claim 16, wherein the step of checking quality includes a visual check.

18. A process as claimed in Claim 16, wherein the step of checking quality includes checking predefined critical dimension(s) of the crawler surface pad (125) to confirm the dimension(s) is (are) within predefined specification(s).

19. A process as claimed in Claim 16, wherein the step of checking quality includes undergoing an abrasion cycle test that is according to the ASTM 4649 ISO Standard.

20. A process as claimed in Claim 16, wherein the step of checking quality includes undergoing an actual functional test, wherein the crawler surface pad (125) after the step of mounting is tested for fittingness.

21. A process as claimed in Claim 16, wherein the step of checking quality includes undergoing a safety test, for ensuring the crawler surface pad (125) after the step of mounting remains physically intact, during an operation of the tractor crawler.

22. A process as claimed in Claim 16, wherein the step of checking quality includes undergoing a terrain test after the step of mounting, wherein the tractor crawler is driven in various terrains such as desert(s), mountain(s), snow and water, as required.

23. A process claimed in Claim 2 further comprising a step of recycling the first pad layer (130) in a recycling means, after the first pad layer (130) is released from the base plate (135).

24. A process as claimed in Claim 23 wherein the step of recycling includes forming pallets for use as infill for artificial grass, such as in football pitches, particularly when the first pad layer (130) is composed of rubber.

25. A process claimed in Claim 23 wherein the step of recycling includes blending the first pad layer (130) with epoxy and manufacturing flooring, for use such as in children's playground, particularly when the first pad layer (130) is composed of rubber.

26. A process claimed in Claim 23 wherein the step of recycling includes extracting oil, when the first pad layer (130) is composed of rubber.

27. A system to re-condition a crawler surface pad (125) as claimed in the process of Claim 2, the system comprising : the releasing means for releasing the first pad layer (130) from the base plate (135);

the cleaning means for cleaning the base plate (135) for removing the residues particularly from the first pad layer (130);

the repairing means for repairing the damages if available, on the base plate (135);

the smoothening means for smoothening the base plate (135);

the applicator means for applying the adhesive onto the at least a portion of the base plate (135);

the compression molding means for molding the base plate (135), the molding means containing the compound for forming the second pad layer (150);

the curing means capable of providing the predetermined ambient, for curing the second pad layer (150);

the inspecting means for inspecting the base plate (135) for the damage and also for inspecting the second pad layer (150) after the curing step, each of the aforementioned means being suitable for accommodating at least one crawler surface pad (125) at a time, while being processed therein.

28. A system as claimed in Claim 27, wherein the releasing means provides at least one of the following: the heat,

the chemical composition, and

the mechanical means.

29. A system as claimed in Claim 27 wherein the cleaning means comprises the sandblasting means, wherein the process is according to Claim 4.

30. A system as claimed in Claim 27 wherein the repairing means comprises the welding means, wherein the process is according to Claim 5.

31. A system as claimed in Claim 27 wherein the repairing means comprises the forging means, wherein the process is according to Claim 6.

32. A system as claimed in Claim 27 wherein the smoothening means comprises the sandblasting means, wherein the process is according to Claim 7.

33. A system claimed in Claim 27 wherein the applicator means further provides for applying the primer, wherein the process is according to Claim 8.

34. A system as claimed in Claim 27, wherein the molding means provides the rubber material, wherein the process is according to claim 10.

35. A system as claimed in Claim 27, wherein the curing means is capable of providing the predetermined ambient, wherein the process is according to Claim 11.

36. A system as claimed in Claim 27, wherein the curing means is capable of providing the predetermined ambient, wherein the process is according to Claim 12.

37. A system as claimed in Claim 27 wherein the inspecting means is capable of checking the thickness of the base plate (135) to confirm it is within the required specification, wherein the process is according to Claim 4.

38. A system as claimed in Claim 27 wherein the inspecting means provides for visual assessment, wherein the process is according to Claim 15.

39. A system as claimed in Claim 27, further comprising the testing means for checking quality, according to the process of Claim 16.

40. A system as claimed in Claim 39, wherein the testing means provides for checking the predefined critical dimension(s), wherein the process is according to Claim 18.

41. A system as claimed in Claim 38, wherein the testing means provides for the abrasion cycle test, wherein the process is according to Claim 19.

42. A system claimed in Claim 27 further comprising the recycling means for the step of recycling the first pad layer (130), wherein the process is according to any one of Claims 23 to 26.

43. A method to recondition a crawler surface pad (125) comprising these steps:- a) releasing the first pad layer (130) from the base plate (135) and providing at least one of the following: the heat,

the chemical composition, and

the mechanical means, b) cleaning the base plate (135) to remove the residues particularly from the first pad layer (130) and including a step of sandblasting, c) repairing the damages if exist, on the base plate (135) and including a step of welding and forging the base plate (135), d) checking visually that the thickness of the base plate (135) is more than 2 mm before proceeding further, e) smoothening the base plate (135) optionally and including a step of sandblasting, f) applying an adhesive onto the at least a portion of the base plate (135), g) compression molding to mold the base plate (135), where the compression molding step includes adding a compound to form a second pad layer (150) and including adding a compound of rubber material of the following composition: approximately 61% of natural rubber, approximately 30% of polybutadiene rubber, and approximately 9% of carbon black and accelerator, the composition being by weight, h) curing the second pad layer (150) affixed on the base plate (135), the ambient conditions according to this step being: approximately 150 degrees centigrade of temperature at 100 to 200 PSI of pressure and for approximately 2 hours, i) inspecting the base plate (135) for the damages and also for inspecting the second pad layer (150) as affixed to the base plate (135), after the curing step, the inspecting steps including checking the thickness of the base plate (135) to confirm it is within the required specification and providing for visual assessment, j) checking quality including the step of checking the predefined critical dimension(s) and the abrasion cycle test, k) recycling the first pad layer (130), wherein each of the aforementioned steps are suitable for accommodating at least one crawler surface pad (125) at a time, while being processed therein

44. A rebuilding process for a crawler surface pad (125) of a crawler element (115) in a crawler loop (110) of a tractor crawler as claimed in Claim 1 , wherein the tractor crawler is a tractor or an armoured vehicle.

Description:
PROCESS AND SYSTEM FOR REBUILDING CRAWLER SURFACE PAD

FIELD OF THE INVENTION

The invention relates to a rebuilding process for a damaged or used crawler loop and crawler surface pad of a vehicle using tractor crawler and to a system for providing the necessary means.

BACKGROUND

The invention relates to the process of rebuilding tractor crawler pads, including retreading the rubber pads and re-building the metal tread. Retreading of tyres generally refer to wheeled vehicles such as automobiles and heavy vehicles. Retreading is the generic term for tyre reconditioning, to extend its useful life for its original purpose, by the addition of a new material. Generally, the tread rubber is the only part of a tyre to wear away, while the structure of the tyre remains intact. Replacing a worn tread makes sound environmental and economic sense. Whilst a car tyre is retreaded only once, commercial vehicle tyres are often retreaded two or three times and aircraft tyres are retreaded many more number of times. Rebuilding of tractor crawler pads goes beyond retreading as it involves re-building the metal treads of the crawler pads so that the entire tractor crawler pad can be re-used.

PRIOR ART

Retreading is performed by removing the worn tyre from the vehicle, followed by an initial inspection to judge its acceptability for further processing. The unwanted worn tread is removed by a process commonly known as buffing, that provides a profile and surface texture suitable for the application of a new tread. The new tread is then applied. Subsequently, the tyre is cured or vulcanized. During the curing process the physical properties of the tread change and the newly applied material forms a permanent chemical bond with the existing casing. After curing, a final inspection is made to rule out any defect which would impair serviceability or the safety of the user. Unacceptable tyres are rejected or scrapped. The unwanted worn tread is often recycled to make rubber mulch or used for other applications. Rebuilding of tractor crawler pads has not been carried out on a commercial scale before because re-building of tractor crawler pads requires the combination of retreading of the rubber portion in the tractor crawler pads as well as re-building the metal treads of the crawler pads.

For a tractor crawler, the use of the crawler wheel assembly instead of wheels help achieve superior floatation and traction. Crawlers are more expensive in maintenance and harder to operate than wheel tractors, but are often critical for working on soft soils, transporting great weights, and particularly for bulldozing. The inventive process refers not only to tractors but any vehicle using tractor crawler pads such as armoured vehicles.

As illustrated by a cross sectional side view of a crawler wheel assembly in Fig.1 , a typical tractor crawler has the crawler loop going around at least two wheels. The crawler loop includes a continuous crawler belt in its innermost edge that rotates with the wheels when the tractor crawler moves. The outer surface of the crawler belt is lined with several individual crawler elements, that join up with each other, forming a crawler surface, as shown in Fig.2. Typically, each crawler element comprises a crawler surface pad that includes a base plate, which is generally metallic, and on top of the base plate is a pad layer that is generally made of rubber for providing reduced frictional effects, during the movement of the tractor crawler. The crawler surface pad is generally connected to the crawler belt by a metallic stud.

When the crawler loop is worn up by usage, it is discarded and replaced by a new one. PROBLEMS IN THE ART

Referring back to Figs.1-2, since the tractor crawlers are commonly used over rough surfaces, it is common for the crawler surface to get damaged at certain localized points, particularly on the crawler surface pads In most cases, the pad layer in a crawler surface pad is damaged and less frequently the base plate is also damaged. Replacing the whole crawler loop to address the issue of a localized damage, is not economical. A localized rebuilding process would be desirable, for the convenience of saving time and cost and such that it will not cause a long downtime of the vehicle during the rebuilding process.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a rebuilding process and a system for a crawler loop of a tractor crawler, that helps in minimizing the downtime for the tractor crawler.

It is another object of the present invention to provide an economical rebuilding process and a system, for a crawler loop of a tractor crawler.

It is another object of the present invention to provide a rebuilding process and a system for rebuilding a crawler loop of a tractor crawler, with available technologies, for ease of implementation.

It is another object of the present invention to provide a rebuilding process and a system for rebuilding a crawler loop of a tractor crawler, that ensures serviceability and safety for the rebuilt crawler loop.

It is another object of the present invention to provide an economical and environmental friendly rebuilding process and a system for rebuilding a crawler loop of a tractor crawler, that is suitable for recycling the damaged pad layer.

These and still other objects, which are made apparent in the following disclosure and description of the invention, are attained in the present invention.

SUMMARY OF THE INVENTION

A first object of the invention is a rebuilding process for a damaged crawler surface pad of a crawler element in a crawler loop of a tractor crawler. The process includes a step of demounting the damaged crawler surface pad selectively from the crawler loop, where the tracking pad comprises a first pad layer affixed to a base plate to form a portion of the crawler loop. The crawler surface pad is then reconditioned and thereafter mounted back onto the crawler loop, without causing a downtime for the tractor crawler during the step of reconditioning, as the tractor crawler can still be used with a few missing crawler surface pads.

Preferably, the step of reconditioning includes further steps of releasing the first pad layer from the base plate by a releasing means, followed by cleaning the base plate for removing residues, particularly of the first pad layer. Thereafter, damages if any, on the base plate are repaired by repairing means and the base plate is preferably smoothened thereafter.

Subsequently, an adhesive layer is applied onto the base plate for fixing a second pad layer on the base plate. The base plate with the adhesive layer is then placed in a compression molding means that provides a compound for forming a second pad layer, that would get affixed to the base plate by the adhesive layer. The second pad layer affixed on the base plate is then cured in a predetermined ambient. Inspection is performed after any of the aforementioned steps for the damages on the base plate. Inspection is also performed on the second pad layer, after the step of curing.

Preferably, the releasing means, at least partially, is one of the following: heat, a chemical composition and a mechanical means.

Preferably, the steps of cleaning and smoothening are by sandblasting.

Preferably, the step of repairing is at least partially, by welding and/or forging, when the base plate is metallic.

Preferably, a primer is applied onto at least a portion of the base plate before the step of applying the adhesive layer, unless the adhesive itself functions also as the primer.

Preferably the compound is a rubber material.

Preferably the rubber material is composed of: approximately 61 % of natural rubber, approximately 30% of polybutadiene rubber, and

approximately 9% of carbon black and accelerator,

the composition being by weight.

Preferably, the step of curing under the predetermined ambient is for 2 hours, at 150 degrees centigrade of temperature and at 100 to 200 PSI of pressure.

Alternatively, the step of curing under the predetermined ambient is for 3 hours, at 160 degrees centigrade of temperature and at 100 to 200 PSI of pressure.

Preferably, a composition of the compound and the predetermined ambient are optimised for achieving various properties of the second pad layer, related to factors such as tensile strength, specific gravity and various mechanical properties including elongation at brake.

Preferably, any of the inspection steps includes checking the thickness of the base plate, to confirm it is within a required specification.

Preferably the inspection steps include visual assessment.

Preferably, after the step of curing, steps of checking quality of the crawler surface pad by testing means, are included in the process.

Preferably, the step of checking quality includes a visual assessment.

Preferably, the step of checking quality includes checking predefined critical dimension(s) of the crawler surface pad with the second pad layer to confirm the dimension(s) is (are) within predefined specification(s).

Preferably, the step of checking quality includes undergoing an abrasion cycle test, that is according to ASTM 4649 ISO Standard.

Preferably, the step of checking quality includes undergoing an actual functional test, wherein the crawler surface pad is mounted onto the crawler loop for ensuring fittingness. Preferably, the step of checking quality includes undergoing a safety test for ensuring the crawler surface pad remains physically intact during an operation of the tractor crawler.

Preferably, the step of checking quality includes undergoing a terrain test, wherein the tractor crawler is driven in various terrains such as desert(s), mountain(s), snow and water, after the reconditioned crawler surface pad is mounted onto the crawler loop.

Advantageously, after the step of releasing, the first pad layer is recycled.

More advantageously, after the step of releasing, the first pad layer is converted into pallets and recycled for use as infill for artificial grass such as in football pitches, when the first pad layer is made of rubber.

More advantageously, after the step of releasing, the first pad layer is recycled by blending with epoxy and manufacturing flooring with the blend, for use such as in children's playground, when the first pad layer is made of rubber.

More advantageously, after the step of releasing, the first pad is recycled for extracting oil, when the first pad layer is made of rubber.

A second object of the invention is a system to re-condition a crawler surface in accordance with the inventive process, the system comprising: a releasing means for releasing the first pad layer from the base plate;

a cleaning means for cleaning the base plate for removing the residues

particularly from the first pad layer;

a repairing means for repairing the damages if available on the base plate;

a smoothening means for smoothening the base plate, after the repairing step; an applicator means for applying the adhesive onto the at least a portion of the base plate, for fixing the second pad layer;

a compression molding means for molding the base plate that is applied with the adhesive layer, the molding means providing a compound for firming the second pad layer that is affixed to the base plate;

a curing means capable of providing the predetermined ambient, for curing the second pad layer on the base plate; and

an inspecting means for inspecting the base plate for the damages and also for inspecting the second pad layer as affixed to the base plate, after

the curing step,

each of the means being suitable for accommodating at least one crawler surface pad at a time, while being processed therein.

Preferably, the releasing means for releasing the first pad layer, at least partially, comprises one of the following: the heat,

the chemical composition, and

the mechanical means.

Preferably, the cleaning means comprises a sandblasting means, for removing the residues particularly from the first pad layer.

Preferably, the repairing means comprises a welding means, for the repairing step of the damages, if available.

Preferably, the repairing means comprises a forging means for the repairing step of the damages, if available.

Preferably, the smoothening means comprises a sandblasting means for the optional smoothening step of the base plate, after the repairing step.

Preferably, the applicator means further provides for applying the primer, when the adhesive is without the primer.

Preferably, the molding means provides the rubber compound for forming the second pad layer.

Preferably the rubber compound has the following composition by weight: approximately 61% of natural rubber,

approximately 30% of polybutadiene rubber, and

approximately 9% of carbon black and accelerator.

Preferably, the curing means is capable of providing the predetermined ambient.

Preferably the predetermined ambient is for 2 hours, at 150 degrees centigrade of temperature and from 100 to 200 PSI of pressure.

Preferably the predetermined ambient is for 3 hours, at 160 degrees centigrade of temperature and from 100 to 200 PSI of pressure.

Preferably, the inspecting means provides for checking the thickness of the base plate to confirm it is within the required specification.

Preferably, the inspecting means provides for visual assessment.

Preferably, the system further comprises a testing means for checking quality of the crawler surface pad, after the curing step.

Preferably, the testing means provide for checking the predefined critical dimension(s). Preferably the testing means provide for the abrasion cycle test.

Advantageously, the system further comprises a recycling means for the recycling step of the first pad layer, such as by: converting into pallets and using them as infill for the artificial grass, such as in football pitches; or

blending with epoxy and manufacturing flooring with the blend, for use such as in children's playground; or

processing for extracting oil;

particularly when the first pad layer is composed of rubber. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, its advantages, and the objects attained by its use, reference should now be made to the accompanying drawings. The accompanying drawings illustrate one or more embodiments of the invention and together with the description herein, serve to explain the workings and principles of the invention.

FIG. 1 illustrates a cross sectional side view of a crawler wheel assembly (100) as in the art, showing the crawler loop (110) going around the wheels (105a, 105b). The figure also illustrates the component parts of the crawler loop (110), including the individual crawler surface pads (125).

FIG. 2 illustrates a perspective view of a chain of crawler surface pads (125) forming a section of the crawler surface (112) in the crawler loop (110), as shown in Fig.1

Fig. 3 illustrates a perspective view of a single crawler surface pad (125) removed from the crawler surface (112), according to an embodiment of the invention.

Fig. 4a illustrates a top view of the first pad layer (130) when released from the base plate (135).

Fig.4b illustrates a top view of the base plate (135) after the first pad layer (130) is released.

Fig. 5 illustrates a cross sectional view of the base plate (135) along a cut line X-X' in Fig.4b, according to an embodiment of the invention.

Fig. 6 illustrates a perspective view of the base plate (135) with the second pad layer (150), according to an embodiment of the invention.

Fig. 7 illustrates a cross sectional view of Fig. 6 along a cut line Y-Y'. DETAILED DESCRIPTION

The present invention relates to rebuilding a crawler wheel assembly (100) in a tractor crawler, partially, for reuse. The structure of a tractor crawler is well known in the art. Referring back to Fig.1 , the cross sectional side view of a crawler wheel assembly (100), of a typical tractor crawler shows the crawler loop (110) going around two wheels (105a, 105b). Many tractor crawlers have the crawler.loop (110) going around more wheels (105a, 105b) and the invention disclosed here is equally applicable to such tractor crawlers. The more the number of wheels, the longer is the length of the crawler loop (110). The crawler loop (110) includes a continuous crawler belt (120) in its innermost edge that rotates with the wheels (105a, 105b) when the tractor crawler moves. The outer edge of the crawler belt (120) is lined with several discrete crawler elements (115), that link up with each other in a line, forming a crawler surface (112), as shown in Fig.2. The crawler element (1 5) typically comprises a crawler surface pad (125) connected to one end of a stud (140) while the other end of the stud ( 40) connects to the crawler belt (120). The stud (140) is generally metallic. The crawler surface pad (125) comprises a base plate (135), which is again generally metallic and on top of the base plate (135) is a first pad layer (130) that is generally made of rubber for providing reduced frictional effects, during the movement of the tractor crawler.

When the crawler loop (110) is worn up by usage, it is discarded and replaced by a new one. The present invention is for a process which rebuilds an individual crawler surface pad (125) as shown in Fig. 3, when damaged. An individual crawler surface pad (125) may get damaged with use. The present invention exploits the fact that the crawler loop (1 0) has several individual crawler elements (115) forming a chain. According to the present invention only a damaged crawler surface pad (125) can be rebuilt for reuse. For rebuilding, the crawler surface pad (125) can be demounted from the crawler loop (110) for reconditioning and mounted back on the crawler loop (110) for reuse. Since the area for each crawler surface pad (125) is small compared to the total length of the crawler loop (110), the tractor crawler can still be used with one or with a few missing crawler surface pad(s) (125), particularly when they are non-adjacent ones. The function of the tractor crawler is interrupted for short durations only during the steps of demounting and mounting the crawler surface pad (125). The crawler loop (110) therefore need not be replaced as a complete unit when partially damaged. If the configuration of the crawler loop (110) so permits, the crawler surface pad (125) may be demounted for reconditioning, along with the stud (140). Upon remounting for the proposed re-building process, the crawler surface pad (125) undergoes visual and dimension checks. If the metal crawler tread is less than 2 mm in thickness, it would not undergo any re-building.

The step of reconditioning according to an embodiment of the invention, includes releasing the damaged first pad layer (130) from the base plate (135) as shown in Figs.4a and 4b, by using a releasing means. Fig. 5 shows a cross sectional view of the base plate (135) along a cut line X-X' in Fig.4b. The releasing means may be heat or a chemical composition or a mechanical means, or a combination thereof. The first pad layer (130) may be melted with heat, particularly at the regions adjoining the base plate (135). Similarly, a chemical composition may be effective either in softening and removal of the whole first pad layer (130) or in softening the adhesive layer under it to result in its release from the base plate (135). Softening the first pad layer (130) by heat or by a chemical composition and thereafter removing the same by wiping off mechanically, is also possible. Alternatively, releasing the damaged first pad layer (130) by only a mechanical means may also be possible, such as with a sharp tool. The process of releasing, according to the invention, is not limited by these methods.

Thereafter the base plate (135) is cleaned for removing residues, particularly of the first pad layer (130). The step of cleaning according to an embodiment of the invention may be done by sandblasting, by a sandblasting means. Sandblasting is a well known method wherein, a surface for cleaning is accommodated in a closed chamber and sprayed with fast moving solid grains such as sand that is propelled by compressed air. According to the present invention, other processes of cleaning may be used as well.

Subsequently, damages if existing on the base plate (135) are also repaired. The damages on the base plate (135) are likely to be holes, cracks and dents, particularly if the base plate (135) is metallic. According to an embodiment of the invention, the step of repairing the holes or cracks is preferably by welding, when the base plate (135) is metallic. Similarly, for a metallic base plate, the dents may be repaired by hot or cold forging. Both welding and forging processes are welt known in the art. The step of repairing is preferably followed by a step of smoothening the base plate (135) for subsequent processing. The step of smoothening, according to an embodiment of the invention, may also be done by sandblasting, by a sandblasting means. The sandblasting required for the step of smoothening may be required to be with more physical energy than that required for the step of cleaning, as cleaning is generally for removal of softer materials. After sandblasting, the metal base plate (135) is visually checked to ensure it is more than 2 mm thick before the rubber pad is added.

Thereafter, an adhesive is applied as an adhesive layer onto at least a portion of the base plate (135) for fixing a second pad layer (150) over it. According to an embodiment of the invention a primer may preferably be applied onto the portion of the base plate (135) before the step of applying the adhesive, unless the adhesive itself functions also as the primer.

The base plate (135) is then molded in a compression molding means, the molding means containing a compound for forming a second pad layer (150) that gets affixed to the base plate (135), by the adhesive. Commonly, the material of the first pad layer (130) is rubber. The material for use in the second pad layer (150) may also be a rubber material. According to an embodiment of the invention, the rubber material, for the second pad layer (150) is composed of approximately 61% of natural rubber, approximately 30% of polybutadiene rubber, and approximately 9% of carbon black and accelerator, the composition being by weight. Other compositions may also be used.

The step of molding is followed by a step of curing the second pad layer (150) affixed on the base plate (135) in a predetermined ambient. According to an embodiment of the invention, the curing step is for 2 hours, at 150 degrees centigrade of temperature and at from 100 to 200 PSI of pressure. Other ambient conditions may also be used. The curing step can be for 3 hours, at 160 degrees centigrade of temperature and at from 100 to 200 PSI of pressure, such factors depending on the nature of the rubber material used.

The composition of the rubber material and the predetermined ambient for curing are preferably optimized for attaining certain desired properties of the second pad layer (150) related to factors such as tensile strength, the specific gravity and various mechanical properties such as the elongation at brake. Such properties may desirably be comparable with those of the first pad layer (130) or be better. After the step of curing, a perspective view of the crawler surface pad (125) is shown at Fig. 6. A cross sectional view of Fig. 6 along the cut line Y-Y' is shown in Fig. 7.

The reconditioning process includes steps of inspecting the base plate (135) for damages such as holes, cracks and dents, after any of the steps. Similarly, the reconditioning process also includes a step of inspection of the second pad layer (150), as affixed to the base plate (135), after the curing step. Any of the inspection steps may include checking the thickness of the base plate (135) to confirm it is within a required specification. Any of the inspection steps may be by visual assessment or by using analytical tools available in the art.

After the step of curing, according to an embodiment of the invention, checking quality of the crawler surface pad (125), with the second pad layer (150) is included, before use. The step of checking quality may include a visual check. The checking may also include measuring certain predefined critical dimension(s) of the crawler surface pad (125) with the second rubber pad (150) to confirm the dimension(s) is (are) within predefined specification(s). An abrasion cycle test, that is according to ASTM 4649 I SO Standard may also be included. Undergoing an actual functional test, wherein the crawler surface pad (125) is fitted onto the crawler loop (110) for ensuring fittingness, may also be included. Similarly, undergoing a safety test for ensuring that the crawler surface pad (125) remains physically intact during an operation of the tractor crawler may also be included. Finally, a terrain test is also preferable, wherein the tractor crawler is driven in various terrains such as desert(s), mountain(s), snow and water, after the crawler surface pad (125) is mounted. The proposed system under this invention provides testing means for checking quality.

Advantageously, with the process as proposed under the present invention, the first pad layer (130) that is released from the base plate (135) is suitable for being recycled, particularly when it is made of rubber. It can be converted it into rubber pallets for use as infill for artificial grass such as in football pitches. Alternatively, it may be recycled by blending with epoxy for manufacturing rubber flooring, for use such as in children's playground. The step of recycling may also be for extracting oil. These process steps may be applied manually or in semi-automated or fully automated systems.

As another object of the invention, a reconditioning system for providing the reconditioning process as described above is also proposed. The system comprises : a) a releasing means for releasing the first pad layer (130) from the base plate (135) and provides at least one of the following: the heat,

the chemical composition, and

the mechanical means, b) a cleaning means for cleaning the base plate (135) for removing the residues particularly from the first pad layer (130) and according to an embodiment, it comprises a sandblasting means, c) a repairing means for repairing the damages if available, on the base plate (135) and according to an embodiment, it comprises the welding means and the forging means, d) a smoothening means for smoothening the base plate (135) optionally and according to an embodiment, it comprises the sandblasting means, e) an applicator means for applying the adhesive onto the at least a portion of the base plate (135), wherein the applicator means according to an embodiment, provides for applying the primer, f) a compression molding means for molding the base plate (135), where the molding means contains the compound for forming the second pad layer (150) and according to an embodiment, the compound is the rubber material of the following composition: approximately 61% of natural rubber, approximately 30% of polybutadiene rubber, and approximately 9% of carbon black and accelerator, the composition being by weight, g) a curing means being capable of providing the predetermined ambient, for curing the second pad layer (150) affixed on the base plate (135), the ambient conditions according to an embodiment of the invention being: approximately 150 degrees centigrade of temperature at 100 to 200 PSI of pressure and for approximately 2 hours, h) an inspecting means for inspecting the base plate (135) for the damages and also for inspecting the second pad layer (150) as affixed to the base plate (135), after the curing step, the inspecting means according to an embodiment, is also capable of checking the thickness of the base plate (135) to confirm it is within the required specification and is preferably also capable of providing for visual assessment, i) a testing means for the step of checking quality that provides for checking the predefined critical dimension(s) and the abrasion cycle test, according to an embodiment of the invention, j) a recycling means for the step of recycling the first pad layer (130) according to an embodiment of the invention, as described under the proposed process, each of the aforementioned means being suitable for accommodating at least one crawler surface pad (125) at a time, while being processed therein. The crawler surface pad (125) to be accommodated may be with or without a stud (140). Each of these means may be manual, semi-automated or fully automated.

A method for reconditioning crawler tractor pad (125) is now described. The steps in this method comprises : a) releasing the first pad layer (130) from the base plate (135) and providing at least one of the following: the heat,

the chemical composition, and

the mechanical means, b) cleaning the base plate (135) to remove the residues particularly from the first pad layer (130) and including a step of sandblasting, c) repairing the damages if exist, on the base plate (135) and including a step of welding and forging the base plate (135), d) checking visually that the thickness of the base plate (135) is more than 2 mm before proceeding further, e) smoothening the base plate (135) optionally and including a step of sandblasting, f) applying an adhesive onto the at least a portion of the base plate (135), g) compression molding to mold the base plate (135), where the compression molding step includes adding a compound to form a second pad layer (150) and including adding a compound of rubber material of the following composition: approximately 61% of natural rubber, approximately 30% of polybutadiene rubber, and approximately 9% of carbon black and accelerator, the composition being by weight, h) curing the second pad layer (150) affixed on the base plate (135), the ambient conditions according to this step being: approximately 150 degrees centigrade of temperature and from 100 to 200 PSI of pressure and for approximately 2 hours, i) inspecting the base plate (135) for the damages and also for inspecting the second pad layer (150) as affixed to the base plate (135), after the curing step, the inspecting steps including checking the thickness of the base plate (135) to confirm it is within the required specification and providing for visual assessment, j) checking quality including the step of checking the predefined critical dimension(s) and the abrasion cycle test, k) recycling the first pad layer (130), each of the aforementioned steps being suitable for accommodating at least one crawler surface pad (125) at a time, while being processed therein. The crawler surface pad (125) to be accommodated may be with or without a stud (140). Each of these steps may be manual, semi-automated or fully automated.

The inventive process is equally suitable for re-building tractor pads or crawler surface pads (125) of tractors and armour vehicles.

OTHER EMBODIMENTS

Reconditioning one crawler surface pad (125) at a time has been discussed here. The proposed system can be adapted to accommodate more than one damaged crawler surface pad (125) simultaneously, for greater efficiency and productivity.

The invention disclosed herein is also applicable for other designs of the crawler loop (110) and its components such as the crawler element (115), the stud (140), the crawler surface pad (125), the base plate (135), the pad layer (130) and the crawler surface (112).

The invention disclosed herein is also applicable for other types of crawler loop (110) such as those used on armoured vehicles and tanks.

The crawler surface pad (125) may be demounted with or without the stud (140), for reconditioning.

The system proposed may be operable in any kinds of the modes: manual, semi-automatic or fully automatic.

Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the claims. ADVANTAGEOUS EFFECTS OF THE INVENTION

The proposed rebuilding process for a crawler surface pad (125) of a crawler element (115) in a crawler loop (110) of a tractor crawler, does not cause a long downtime for the tractor crawler, as the tractor crawler can be used without a substitute, while the individual crawler surface pad (125) is being reconditioned. The only downtime of the tractor crawler is while demounting the crawler surface pad (125) for reconditioning and while mounting it back thereafter.

Since the rebuilding process is for a single or a few crawler surface pad(s) (125) which is (are) damaged, the extent of reconditioning is at a smaller scale than when the whole crawler loop (110) is reconditioned, hence the proposed process is more economical.

For the reconditioning of the crawler surface pad (125), standard technologies are proposed for the system. Hence, only certain physical adaptations may be required, such as for accommodating the crawler surface pad (125) during the processing.

The proposed rebuilding process is suitable for retrieving the damaged first pad layer (130) for recycling, which is an economical and environment friendly approach.