GB2148218A

GB2148218A - The connection and release of adjacent members of a traction chain of a tracked vehicle

Info

Publication number: GB2148218A
Application number: GB08422605A
Authority: GB
Inventors: Helmut Bentz
Original assignee: O&K Orenstein and Koppel GmbH
Current assignee: CNH Industrial Baumaschinen GmbH
Priority date: 1983-09-09
Filing date: 1984-09-07
Publication date: 1985-05-30
Also published as: IT8448812A1; JPS60174369A; IT8448812A0; GB8422605D0; IT1178416B; FR2551821A1

Abstract

The connection of adjacent end members of a traction chain of a tracked vehicle utilizes a track end pin (1) inserted with an easy fit into the outer link plate eyes (2) of one of the end members and through the inner link plate sleeve 3 of the other end member. A press fit of the pin (1) in the region of the outer link plate eyes (2) is achieved by pulling a cone (9) into a tapering hollow (6) provided at each end face of the pin. The cone is pulled into the hollow using a tension screw (12) and can subsequently be pushed out of the hollow using a release screw (19) to enable the chain to be dismantled. <IMAGE>

Description

SPECIFICATION The connection and release of adjacent members of a traction chain of a tracked vehicle The invention relates to the connection and release of adjacent end members of a traction chain of a tracked vehicle.

The growing industrialisation of the world economy is being accompanied increasingly by a working both of coal-bearing strata and of ore-bearing rock and limestone rocks in open cast mining.

Earth-moving machines, especially loading shovel excavators, that are easily manoeverable at the immediate strata being worked, are used for this purpose. With the object of optimising the process, there is an increasing tendency to turn to bigger and bigger shovel loads, so that the size of the excavators overall increases too. This also applies to their travelling mechanisms, in particular to the size of tracks employed.

The manufactures of crawler excavators often obtain the tracks required for the travelling mechanisms from subcontractors specialising in this field, each track being in the form of a length of track which is then closed on assembly using an end pin to form a ring of track.

The subcontractor, who is equipped with machines specially suited to this purpose, connects individual track links to form a length of track using track pins which have a press fit in the outer link plate eyes and a loose fit in the inner link plate eyes or in a sleeve pulled therebetween. To achieve the press fit in the outer link plate eyes, very high pressures are required, which necessitate the use of expensive machines for that purpose.

The excavator manufacturer, having obtained such a length of track from the subcontractor, is then faced with the problem of imparting a firm fit similarly to the end pin that is to be used for closing the track. In the case of previously-used tracks of conventional size he was able either to make use of mobile presses, orto resort to special measures.

These measures include, for example, the method of intensively supercooling the track pin, that is to say, causing it to contract to an extraordinary degree and then, at this temperature, rapidly pressing it into the end members to be joined to achieve at normal temperature, a press fit of adequate firmness.

However, even though the problem of closing the ring of track could be overcome particular difficulties were still presented when the ring of track had to be re-opened on site, whether because of damage to the track or because of any other damage which necessitated dismantling of the track. The methods used to re-open the ring of track, such as burning out parts of the track members or the track end pin can only be described, in the last analysis as unsatisfactory. They not only involve the earth-moving machines being idle for considerable periods at very high machine hour rates, to the detriment of the operators, but also present the problem of transporting increasingly large lengths of track after dismantling for repair purposes or, indeed, of whether to transport them at all.

The object of the present invention is to enable the connection and release of adjacent end members of a traction chain to be simplified.

The present invention provides a process for connecting adjacent end members of a traction chain for a tracked vehicle by means of a track end pin, in which process a press fit of the pin in one of the end members is achieved by pulling an insert member into each end of the pin. The insert member may be pulled into the pin by a tension screw passing through the insert member and gripping the pin.

In a process in accordance with the invention, release of the pin is achieved by disengaging the insert member from the pin. The insert member may be disengaged from the pin by a release screw supporting in the insert member.

In an embodiment of the invention, the insert member is cone-shaped and is pulled into a tapering hollow in the end of the pin. In this embodiment, the tension screw head applies a force to the base of the cone. The force may be applied to the cone base via a washer. In this embodiment, the release screw pushes the cone from the hollow with the shank head of the screw acting on the bottom of the hollow: alternatively, however, the release screw may push the cone from the hollow with the underside of the screw head acting on the pin edge, in which case the screw head may act on the pin edge via a force transfer element.

The invention further provides an arrangement for carrying out a method as defined above utilizing a cone-shaped insert member which is pulled into a tapering hollow in the end of the pin. In this arrangement the pin. In this arrangement the pin commencing from each of its end faces, is provided with a tapering hollow, a pin bore and a pin thread, all in alignment, and a centrally-open cone that fits into the hollow is provided, which cone, commencing from its base, has a bore with an adjoining screw thread, and may be pulled into the hollow by a tension screw passing through the cone and engaging the pin thread or may be disengaged by a release screw supported in the screw thread of the cone and pushing away at the pin.

To improve the degree of effectiveness with which the pin is pressed into the end member, the outer surface of the cone may be provided with a coating.

This coating preferably has a friction-reducing property and may, for example, be an MoS2 coating.

When the cone has been pulled with the aid of the tension screw fully into the tapering hollow to achieve the press fit of the track end pin in the end member, the tension screw head is preferably located completely within the hollow. External mechanical influences, which could lead to the functional elements being damaged, orto objects grazing the track profile, are therefore avoided.

To prevent the ingress of water and therewith the formation of rust between the cone and the tapering hollow, a sealing groove with a sealing ring is preferably provided, in the vicinity of the base of the cone, in the outer surface of the cone.

By way of example, an embodiment of the invention will be described with reference to the accom panying drawing which illustrates schematically the connection and release of adjacent end members of a traction chain.

In the left-hand part of the drawing, the end links of the traction chain are shown in the final assembled state, that is to say, connected by an end pin as will be described below whilst the right-hand part of the drawing illustrates the dismantling of the connection.

In the left-hand part of the drawing, the end pin 1 is secured with a press fit in the outer link plate eyes 2 of one end member of the traction chain while the sleeve 3 of the inner link plates 4 of the other end member surrounds the middle part of the end pin with freedom of movement. The pin 1, commencing from each of its end faces 5, is provided with a tapering hollow 6, a pin bore 7 and a pin screw thread 8, all in alignment. Within the hollow 6, there is fitted therein a centrally-open truncated cone 9, the central opening comprising a plain bore 10 and a screw thread 11 adjoining it, wherein the bore 10 is located at the outer end, nearest the cone base, and the screw thread 11 is located at the end nearest the truncated part of the cone.The drawing also shows a tension screw 12 drawn into the hollow 6, through the central opening in the cone 9, by engagement with the thread 8. To enable this to be achieved, the diameter of the pin screw thread 8 is smaller than that of the pin bore 7, which in its turn is smaller than the diameter of the screw thread 11, the bore 10, finally, having the largest diameter.

It will be appreciated that, as the tension screw 12 is drawn into the hollow 6, the cone 9 is also pulled into the hollow and brings about a resilient increase in the diameter of the surrounding portion of the end pin 1 and the required press fit of the latter in the outer track link eye 2.

It is of advantage in carrying out this operation to provide the cone 9 with a coating having a friction reducing property.

The base 13 of the cone is provided with a turned groove 14 in which is inserted a plain washer 15.

This avoids the tension screw head 16 binding into the material of the cone as the tension screw 12 is screwed down, and avoids unnecessary friction forces being generated. Advantageously, the plain washer 15 is therefore also of hardened and ground construction.

In order to avoid water penetrating between the outer surface of the cone and the hollow 6, a sealing groove 17 is turned in the outer surface of the cone in the vicinity of the cone base and is filled by a sealing ring 18.

The right-hand part of the drawing illustrates the disengagement of the cone 9 with the aid of a release screw 19. For the sake of clarity, in this part of the Figure the corresponding elements of the left-hand part are not individually numbered. The release screw supports itself in the screw thread 11 of the cone 9 and with its shank head 20 pushes away from the bottom 21 of the hollow 6, thereby pushing the cone 9 out of the hollow 6 and allowing the chain to be dismantled.

An alternative arrangement for disengaging the cone 9 is such that, as the release screw 19 is rotated, the underside of its screw head 22 pushes away, either directly or indirectly by way of a sleeve or washer-like force element from the pin edge 23.

For the sake of completeness, it should be mentioned that disengagement of the cone 9, when the release screw 19 is screwed into it, is also possible with the help of withdrawal devices.

An advantage of the arrangements described above is that the closing of the ring of track by the end pin at the excavator manufacturer is uncomplicated and, moreover, the same applies, if need be, for the opening and dismantling of the track at the location where the earth-moving machine is being operated. This is of particular importance when the location at which the apparatus is being used lies in areas not developed industrially. It is particularly advantageous to provide a track with not just a single end pin 1 but with several thereof, for example three or four, so that it is easily possible, merely by using makeshift means, to remove portions of track, which are easily transportable and can be replaced, if necessary, at comparatively little expense. In special cases, it is then even worth considering incorporating a portion of track in the standard replacement part equipment.

A special problem which may arise with the arrangements described is that of achieving a press fit that is as uniform as possible over the area of the outer link plate eye 2. To achieve such a fit, it is necessary for the pressed-in cone 9 to be placed with substantially uniformly distributed pressure against the wall of the tapered hollow 6 and, to this end, it has proved advantageous to manufacture the cone 9 with a concave deviation from the ideal conical form.

Because the wall thickness of the cone varies in dependence on the height of the cone, this concave deviation is asymmetric.

Claims

1. A process for connecting adjacent end members of a traction chain for a tracked vehicle by means of a track end pin, in which process a press fit of the pin in one of the end members is achieved by pulling an insert member into each end of the pin.

2. A process according to claim 1, in which the insert member is pulled into the pin by a tension screw passing through the insert member and gripping the pin.

3. A process according to claim 1 or claim 2, in which the release of the pin is achieved by disengaging the insert member from the pin.

4. A process according to claim 3, in which the insert member is disengaged from the pin by a release screw supported in the insert member.

5. A process according to any one of the preceding claims, in which the insert member is coneshaped and is pulled into a tapering hollow in the end of the pin.

6. A process according to claim 5 when appendant to claim 2, in which the tension screw head applies a force to the base of the cone.

7. A process according to claim 6, in which the force is applied to the cone base via a washer.

8. A process according to claim 5 when appen dantto claim 4, in which the release screw pushes the cone from the hollow with the shank head of the screw acting on the bottom of the hollow.

9. A process according to claim 5 when appendant to claim 4, in which the release screw pushes the cone from the hollow with the underside of the screw head acting on the pin edge.

10. A process according to claim 9, in which the screw head acts on the pin edge via a force transfer element.

11. An arrangement for carrying outthe method according to claim 5, in which the pin, commencing from each of its end faces, is provided with a tapering hollow, a pin bore and a pin thread, all in alignment, and in which a centrally-open cone that fits into the hollow is provided, which cone, commencing from its base, has a bore with an adjoining screw thread, and may be pulled into the hollow by a tension screw passing through the cone and engaging the pin thread or may be disengaged by a release screw supported in the screw thread of the cone and pushing away at the pin.

12. An arrangement according to claim 11, in which the release screw is such that its shank head pushes away at the bottom of the hollow.

13. An arrangement according to claim 11, in which the release screw is such that the underside of its screw head pushes away from the pin edge either directly or indirectly by way of a force transfer element.

14. An arrangement according to any one of the preceding claims, in which the diameter of each of the following items is in each case smaller than that ofthe succeeding one: pin thread, pin bore, cone screw thread and cone bore.

15. An arrangement according to any one of the preceding claims in which in the base of the cone there is provided a turned groove with a washer inserted therein.

16. An arrangement according to any one of the preceding claims in which, in the outer surface of the cone, in the vicinity of the cone base there is provided a sealing groove with a sealing ring.

17. An arrangement according to any one of the preceeding claims in which the outer face of the cone is provided with a coating.

18. An arrangement according to claim 17, in which the coating has a friction-reducing property.

19. An arrangement according to claim 18, in which the outer face of the cone is coated with an MoS2 coating.

20. An arrangement according to any one of claims 11 to 19, in which the tension screw head is arranged completely within the hollow when the cone is pulled into the pin.

21. An arrangement according to any one of claims 11 to 20, in which the cone generating line of the un-stressed insertion piece deviates, along its length, from the ideal straight line.

22. An arrangement according to claim 21, in which the cone generating line of the un-stressed insertion piece deviates in a concave manner from the ideal straight line.

23. An arrangement according to claim 22, in which the concave deviation is asymmetric.

24. A process according to any one of claims 1 to 10, substantially as described herein with reference to the accompanying drawings.

25. An arrangement for connecting and/or releasing adjacent end members of a traction chain of a tracked vehicle, the arrangement being substantially as described herein with reference to, and as shown in, the accompanying drawings.