[DESCRIPTION]

[001] Field of the invention

[002] The present invention refers to a spiked plate for snow chains, in particular to a plate for a wheel rolling track for lorry snow chains.

[003] BACKGROUND ART

[004] As known, variously-shaped anti-skid devices or snow chains exist for vehicles. In the present disclosure, we shall deal with those devices - greatly appreciated today, due to a series of advantageous peculiarities - which may be applied and fixed to the front of the wheel, without having to act also on the rear side of the tyre.

[005] These semi-automatic fitting chains provide a wheel rolling track equipped with anti-skid elements (portions of metal chain, metal cross pins, spiked plates, and so on), intended to lie between the tyre and the road surface to ensure road grip, which track is held on the tyre by connecting arms or spokes.

[006] The connecting arms, which have a varying degree of flexibility, are further attached to the vehicle wheel by variously-shaped retaining means.

[007] A particularly critical and demanding application field, where this kind of chain is advantageous, is that of lorry tyres. In that respect, reference can be made to EP 313.520.

[008] Particularly for this application, two significant problems are felt: one concerns the system fitting the device to the wheel and the other concerns the opportunity for adjustment of the chain to the tyre size. In the present application, the latter problem will be addressed, while the former is addressed in a separate, application having the same priority date.

[009] As known, the so-called wheel rolling track is arranged and dimensioned so as to strictly adhere to the wheel tread, after it has been mounted partly by hand on the tyre and pushed into its working position by the action of the spokes and of the elastic attachment means .

[010] However, in order to achieve effective operation, also during the mounting step, it is necessary for the wheel rolling track to be capable of adapting its length to the actual circumferential dimensions of the tread.

[011] Generally, the wheel rolling track has substantially rigid, hence not length-adjustable, spiked plates (see EP 351.362), connected by

portions of inextensible metal chain.

[012] In order to adjust the length of the wheel rolling track to the current tyre conditions, it has hence been suggested to use tensioning devices, arranged at a point of convergence of two adjacent portions of chain, which are thereby apt to be shortened or lengthened by rotating the tensioning device.

[013] This tensioning device, however, is not completely reliable, it introduces assembling complexity which negatively affects costs, and is excessively subject to contact with the road surface, resulting in likely wear.

[014] The object of the present invention is hence that of providing a system for the adjustment of the wheel rolling track which overcomes the drawbacks set forth above.

[015] Such object is achieved by means of a device as described in its essential features in the attached main claim.

[016] Other inventive aspects of the device are described in the dependent claims .

[017] Further features and advantages of the device according to the invention will in any case be more evident from the following detailed description of a preferred embodiment, given by way of example and illustrated in the accompanying drawings, wherein:

[018] fig. 1 is a cross-section view of an exemplary tyre, whereon a snow chain is mounted equipped with the device of the invention;

[019] fig. 2 is a perspective view of a spiked plate according to the invention; and

[020] figs. 3A and 3B are perspective views of another embodiment of the plate according to the invention, assembled and exploded ones, respectively .

[021] Fig. 1 shows an exemplary snow chain mounted on a lorry tyre P. The drawing shows spiked plates 1 wherefrom two portions of metal chain 2a and 2b depart, forming a wheel rolling track. Supporting arms 3 are further connected to plates 1, which arms converge towards the rotation axis of tyre P and are fixed on the front side of rim C by suitable retaining means. These last components will not be described in further detail here, since they are not the subject of the present invention .

[022] Spiked plate 1 has a general structure, known per se, comprising a main body 10, a double pair of anchoring blocks 11, on the two

opposite fronts from which the chain branches depart, and a lateral fastening extension 12 which, in its mounted position, descends along the side of tyre P.

[023] Main body 10 is generally molded in a plastic material wherein a series of metal studs is embedded, according to various embodiments, intended to grip the slippery road surface (for example due to snow or ice) .

[024] Lateral extension 12 has suitable fastening means, for example a bolt 12a with corresponding nut 12b, whereby plate 1 is joined to the peripheral end of arms 3.

[025] Anchoring blocks 11 are arranged to engage therewith the end links of pairs of chains forming part of the wheel rolling track. In particular, pairs of blocks 11 are provided on both the opposite front edges of plate 1, so as to allow to engage therewith the ends of a pair of inbound chains 2a, 2b and a pair of outbound chains 2a', 2b', and to complete the continuity of the wheel rolling track which is closed in a loop around the tyre.

[026] According to the invention, the pair of anchoring blocks 11, at least on one of the plate edges, is equipped with anchoring means which may be opened. In particular, as can be seen in figs. 2, 3A and 3B, each anchoring block 11 has a vertical slit 11a which serves as housing for a rocking element 13, mounted on its edge, whereto the end link of chains 2a and 2b can be fastened. For such purpose, rocking element 13 has, in its front portion, an open eye 13a - whereto the end link of chain 2a or 2b can be fastened - and a closed eye 13b, whereby the rocking element is attached to plate 1.

[027] In order to attach rocking element 13 to anchoring blocks 11, a pin 14 is provided, which runs across seat 11a and eye 13b.

[028] As can be seen in fig. 2, open eye 13a is preferably at an angle, with a backward and tyre-bound inclination, so that the traction imparted by the chain branch, therewith engaged, may improve mutual engagement .

[029] Finally, the front portion of anchoring block 11 advantageously has a recess or splay lib which affects a good portion of the block thickness, except for a bottom portion lie which protrudes lip-wise towards the front side. On this last part of protruding bottom lie, a groove Hd is formed, which represents the continuation of slit Ha.

[030] Rocking element 13 further has a front notch or indent 13c, which

is arranged to engage with the front wall of groove Hd, this engagement being maintained by the tensioning action of chain branches 2a, 2b.

[031] Rocking element 13 can thereby be housed and retained in position in the slit Ha and in the groove Hd, after having engaged the end link of chain 2a or 2b with open eye 13a.

[032] Should it be desirable to shorten chain branches 2a and 2b, rocking element 13 may be pushed backwards (exploiting the play allowed by eye 13b), disengaging indent 13c from groove Hd. Thereafter it is possible to rotate rocking element 13 upwards about pin 14.

[033] Once rocking element 13 has been rotated and lifted out of groove Hd, it is possible to further lift it out of slit Ha, again exploiting the play allowed by eye 13b.

[034] At this point, it is possible to slip the end link out of open eye 13a and to instead introduce therein the last-but-one link, arranging the last end link in a substantially perpendicular position thereto, thereby shortening the corresponding chain branch.

[035] Finally, rocking element 13 can be again inserted and blocked in its seat by a reverse process, the last link of the chain - now free and tension-free - being able to be at least partly housed in the splay Hb.

[036] According to a preferred embodiment (figs. 3A and 3B), the two end links, which remain free following shortening, are positioned forcing each other in the same direction (i.e. towards the central axis of plate 1) and subsequently joined by a connecting element, for example by a half-ring 15 obtained from a bent-down steel rod. Advantageously, this half-ring 15, in addition to keeping the two opposite free links stationary, can itself act as an element of engagement with the road surface, which improves the gripping function of the wheel rolling track.

[037] The solution offered here fully achieves the objects set forth in the preliminary remarks. As a matter of fact, rocking element 13 - provided it is suitably designed - remains protected from impacts with the road surface; moreover, the system is sturdy, reliable and easily manoeuvrable by the user.

[038] As shown, only one pair of rocking elements 13 can be provided on a single front edge of each plate 1 or on both edges in alternate positions; should it instead be desirable to further widen adjustment

opportunities, it can be provided for rocking elements 13 to be provided on all four blocks of each plate 1: certainly, complete removal of the rocking elements (with the resulting attachment of the chain links directly to pin 14, as shown in the top part of fig. 3A) or the addition of rocking elements, on one of the two edges of connection plate 1, already itself implies an effective adjustment capability.

[039] According to a preferred embodiment of the invention, pin 14 for the attachment of rocking elements 13 is in the shape of an arch- shaped steel rod (fig. 3B) , whose parallel arms represent the fastening pins for rocking elements 13 or directly for fastening the end links of the chain branches. This solution comprises the further advantage of restoring the continuity of a metal path - having suitable mechanical strength - connecting the chain branches of the wheel rolling track, regardless of the material of which main body 10 of plate 1 is made of. This ensures improved strength of the wheel rolling track, with no limitations concerning the choice of the material of plate 1, which allows to easily overcome the strict certification tests of these snow chains without affecting manufacturing costs .

[040] It is intended, however, that the invention is not limited to the specific embodiment illustrated above, which represents only a non-limiting example of the scope of the invention, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of the invention.