Technical Field

The present invention relates to a track chain.

Background Art

Chains are known which are formed by a succession of links articulated two by two by means of a respective pin, closable in a loop, and adapted to the realization of tracks for tractors, excavators or similar vehicles.

Clearly, in use, the tracks are wrapped around the toothed wheels of the vehicles.

On each pin is mounted a rotating bushing adapted to be directly affected by the teeth of the toothed wheel, during the movement of the above-mentioned vehicles.

These track chains are lubricated, in order to reduce the wear of the links, in correspondence of the pin friction surfaces designed to support the load and to avoid the persistent problem of dust accumulation between pin and links or between adjacent links.

In detail, in the known chains, the pin comprises a special tank for the lubricating fluid and channels for supplying the friction surfaces with fluid. Consequently, these chains must provide sealing elements to limit the leakage of lubricant which is, however, inevitable.

This solution is very expensive due to the manufacturing complexity of this type of link and because of the lubricant cost.

Description of the Invention

The main aim of the present invention is to provide a track chain that it is cheaper than known chains, while offering the same performance.

Another object of the present invention is to provide a track chain which allows to overcome the mentioned drawbacks of the prior art within the ambit of a simple, rational, easy and effective to use solution.

The above mentioned objects are achieved by the present track chain according to claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become better evident from the description of a preferred, but not exclusive embodiment of a track chain, illustrated by way of an indicative, but not limitative example in the accompanying drawings in which:

Figure 1 is a top, partially broken away, view of a portion of the chain according to the invention;

Figure 2 is a cross-sectional view of the chain according to the invention, taken along the plane II - II of Figure 1; and

Figure 3 is a side view of a length of the chain according to the invention.

Embodiments of the Invention

With particular reference to such figures, reference numeral 1 globally designates the track chain of the invention.

The chain 1 first of all comprises a plurality of links 2, 3, 2', 3', 2", 3" hinged two by two, each of which comprises a pair of lateral semi-links 2, 3, 2', 3', 2", 3" (see Figures 1 and 2).

In practice, the semi-links 2, 3, 2', 3', 2", 3" are spaced away from one another and define the sides of the chain 1.

Therefore, the semi-links 2, 3, 2', 3', 2", 3" arranged along the same side will be referred to below as "semi-links of the same side"; furthermore, after having selected an orientation of the longitudinal extension of the chain 1, it is possible to speak of right and left semi-links 2, 3, 2', 3', 2", 3".

It should be noticed that the chain 1 can be open or closed in a loop, one or more openable links 2', 3' being provided as described in a later paragraph.

Each semi-link 2, 3, 2', 3', 2", 3" comprises a first and a second through hole 4, 5, preferably circular, which have an axis X transversal to the length of the semi-link 2, 3, 2', 3', 2", 3" and are arranged in correspondence of (or near) the opposite extremities of the semi-link 2, 3, 2', 3', 2", 3".

In practice, the first and second holes of a semi-link 2, 3, 2 3', 2", 3" are substantially coaxial with the first and second holes of the other semi-link 2, 3, 2', 3', 2", 3" comprised in the same link of chain 1.

Preferably, as shown in Figures 1 and 2, the semi-links 2, 3, 2', 3', 2", 3" of each link are symmetrical with respect to a median longitudinal plane P of chain 1. As shown in Figures 1 and 2, the proposed chain 1 further comprises a plurality of hinge pins 6, preferably cylindrical and full, arranged transversal to the chain 1 itself, each of which hinges a pair of adjacent links 2, 3, 2', 3', 2", 3".

In particular, each pin 6 is inserted both in the first holes 4 of the semi-links 2, 3, 2', 3', 2", 3" of a given link, and in the second holes 5 of the semi-links 2, 3, 2', 3', 2", 3" of the other link of the pair, to define their mutual articulation.

Additionally, the invention provides a plurality of rotating bushings 7, preferably annular and circular, each mounted revolving on the respective pin 6, so as to be concentric with, and interposed between the semi-links 2, 3, 2', 3', 2", 3" connected by the pin 6.

According to an advantageous solution of the invention, the bushings 7 and the semi-links 2, 3, 2', 3', 2", 3" are dry-mounted on the corresponding pins 6.

With the expression "dry-mounted" it is meant not only that the above mentioned components of the invention are fitted on the pins 6 in the absence of lubricating fluids, but also, by equivalence, that there is a total absence also of powdered lubricants or of other kind.

In practice, the chain 1 of the invention, also in use, is free of lubricating substances of any kind.

Therefore, the proposed chain 1 does not comprise either lubricant supply channels or tanks.

Preferably, each semi-link 2, 3, 2', 3', 2", 3" comprises an inner annular recess 8 formed in correspondence of the inner surface of the second hole 5 (as seen in particular in Figure 2).

In this case, in the semi-links 2, 3, 2', 3', 2", 3" of a same side, articulated on the same pin 6, the surface of the recess 8, together with the lateral surface of the pin 6 and with the surface of an extremity edge 9 of the respective bushing 7, define an inner chamber which accommodates dry a corresponding bearing 10 fitted on pin 6.

In practice, each pin 6, and therefore each pair of articulated links 2, 3, 2', 3', 2", 3", is associated with two bearings 10, preferably annular, such as a bushing or the like, concentric to the corresponding pin 6.

Each bearing 10 is accommodated to measure in the respective chamber, at least in the direction defined by the thickness, so that its outer lateral surface directly contacts the inner friction surfaces of the semi-links 2, 3, 2', 3', 2", 3".

Even more in detail, each semi-link 2, 3, 2', 3', 2", 3" can comprise a longitudinal innermost portion 11, with respect to the median plane P of the chain 1, and a longitudinal outermost portion 12.

In the innermost portion 11 is formed the above-mentioned first hole 4 and in the outermost portion 12 is formed the second hole 5.

The invention envisages that the two innermost portions 11 of a given link 2, 3, 2', 3', 2", 3" are contained laterally between the two outermost portions 12 of a different link hinged to the first one.

For the purposes of the correct articulation between the links 2, 3, 2', 3', 2", 3", it is preferable that the outer portions 12 of a link are blocked in rotation with respect to the respective pin 6, while the inner ones 1 1 of the other link are revolving. '

It should be noticed that, as seen in Figure 3, the outer portions 12 of a given link are substantially contiguous to the inner ones 11 of the link articulated to the first one, and that these are adjacent to the respective bushing 7; since the bearings 10 are included to measure, and because the walls that define the relative chambers are substantially contiguous, then the amount of dust that can creep between the innermost surfaces of chain 1, and especially between the bushings 7 and the pins 6 or between the bearings 10 and the pins 6, is very limited.

However, for the purpose of minimizing the possibility that dust can flow into the small spaces inside chain 1, defined along the friction surfaces, the invention preferably provides for the advantageous solutions described below. As shown in detail in Figure 1, but particularly in Figure 2, each bearing 10 is sandwiched between first and second dust cover means 13 included in said chamber.

The first dust cover means 13 are inserted between the bearing 10 and the outermost portion, while the second dust cover means 13 are inserted between the bearing 10, the bushing 7 and the innermost portion, to define, between the bushing 7 and the pin 6 and between the bearings 10 and the pin 6, the areas of chain 1 which are completely isolated from the outside. The dust cover means 13 can be of the elastic type and shall be inserted with interference in the respective chamber; preferably, they have a configuration in the manner of a cup spring.

The outermost portions 12 can comprise one or more protection wings 15 arranged in correspondence of the mentioned outer edges 14.

For example, the outer edge 14 of each second hole 5 can comprise two wings 15 having the shape of a C or of a ring section, concentric to the gap of the hole 5.

The wings can be formed either in an integral body piece with the relative outermost portion 12 or be added to this.

In detail, the wings 15 protrude outwards of the respective outermost portion 12, in the axial direction to the second hole 5.

The invention can also provide anti-slipping means 16 arranged in correspondence of the outer edges 14 of the second holes 5 and able to prevent axial translations of the pin 6.

Such anti-slipping means can comprise snap rings 16 applicable to the respective pin 6, in correspondence of respective grooves formed in it, by means of the aforementioned external access.

Thanks to the fact of providing the protection wings 15, the invention advantageously obtains the result that, once tracks are mounted made with the chain 1 of the invention on a tracked vehicle, the pins 6 and the respective snap rings 16 are protected by impact of gravel or the like.

As anticipated above, and as can be seen in particular in Figure 3, the proposed chain 1 can comprise at least an openable link 2', 3', which comprises two lateral counter-links, each formed by a lateral member 17 connected to the same pin 6, and fixable in a releasable manner to a respective member 18 of the other counter-link on the same side, to define a semi-link 2', 3'.

In practice, each semi-link 2', 3' of the openable link comprises a first member 18 which conforms the above mentioned outermost portion 12 and a separate second member 17 that conforms the innermost portion 11.

The first member 18 is joined to the second member 17 in correspondence of a respective coupling indented profile, and is fixed to it, e.g., by means of releasable locking means, such as screws 19 or the like, which are inserted into suitable threaded holes 20 provided in the two members 17, 18.

It has in practice been ascertained how the described invention achieves the proposed objects and in particular the fact is underlined that the friction surfaces, affected by the loads acting on chain 1 of the invention, are completely isolated from dust and are devoid of any lubricating agent.