A varying-track wheel with a dowel-pin centring system

Abstract: A varying-track wheel comprises a rim (11) with fastening elements (12) projecting towards the rotation axis of the wheel and a disc (14) peripherally secured in a removable manner to said fastening elements by means of bolts (15). The wheel comprises at least two devices (16) for a precise mutual positioning of the disc and rim. Each of such devices is operatively disposed close to one of said fastening elements (12) and in turn comprises a tubular seat (17) on the fastening element (12) to removably receive one end of a dowel pin (18) the other end of which projects towards the disc to be fitted into a centring hole (19) formed in the periphery of the disc itself.

Description: The present invention relates to a varying-track wheel provided with a device for a precise positioning of the rim relative to the disc. Varying-track wheels, comprising the features of the preamble of claim 1 are already known in the art from WO-A-00/12328, i.e. wheels in which the rim is fastened in a removable manner to the central disc by means of appropriate brackets enabling selection of the distance between the disc plane and the median plane of the rim. These wheels are used on agricultural vehicles such as farm tractors, so that a user can each time vary the vehicle track between a certain number of possible choices (eight for example), depending on requirements. A problem of known varying-track wheels is to keep a satisfactory radial positioning between the rim and disc when the track is varied. In particular, the continuous increase in the maximum speed of farm tractors makes it increasingly more critical to vary the radial unevenness with respect to the values that are ensured at the factory where mounting of the disc on the rim is carried out by means of special equipment adapted to centre the disc relative to the rim itself. To avoid the above problem, over a given speed (generally 40 km/h) wheels with a varying track are not used and wheels with a disc welded to the rim are employed, in which clearly the radial unevenness is constant and can be only affected by the fit backlash of the wheel with the vehicle hub. It is a general aim of the present invention to obviate the above mentioned drawbacks by providing a varying-track wheel equipped with a simple, reliable and precise device for mutual positioning of the rim and disc. In view of the above aim, in accordance with the invention, a varying-track wheel has been conceived which comprises a rim with fastening elements projecting towards the rotation axis of the wheel and a disc peripherally secured in a removable manner to said fastening elements by means of bolts, characterised in that it comprises at least two devices for a precise mutual positioning of the disc and rim, each of said devices being operatively disposed close to one of said fastening elements and comprising a tubular seat on the fastening element to removably receive one end of a dowel pin the other end of which projects towards the disc to be fitted into a centring hole formed in the periphery of the disc itself. For better explaining the innovative principles of the present invention and the advantages it offers over the known art, a possible embodiment applying these principles will be described hereinafter with the aid of the accompanying drawings. In the drawings: Fig. 1 is a front view of a wheel in accordance with the invention; Fig. 2 is a partial view in section taken along line II-II in Fig. 1. With reference to the drawings, a varying-track wheel made following the principles of the present invention and generally identified by reference numeral 10, is shown in Fig. 1. Wheel 10 comprises a rim 11 of a substantially known configuration and adapted to externally receive a tyre (not shown). The rim 11 has fastening elements 12 on its inner face, which are spaced apart from each other along the rim circumference and project towards the rotation axis 13 of the wheel for peripheral fastening of a disc 14 in a removable manner, by means of bolts 15. Close to at least one of the fastening elements 12 the wheel comprises a device 16 for a precise mutual positioning of the disc and rim. As viewed from Fig. 1, advantageously the fastening devices 16 are two in number and are disposed close to opposite fastening elements 12. As can be clearly seen in Fig. 2, each device 16 comprises a tubular seat 17 advantageously made up of a section of tube jig-welded to the fastening element, which removably receives one end of a dowel pin 18 the other end of which projects towards disc 14 to be fitted into a centring hole 19 formed in the periphery of the disc itself. Still advantageously, the tube section welded to the fastening element with its axis parallel to the corresponding bolt 15, has a length that does not exceed the thickness of the fastening element in order not to jut out at the two sides of the latter, as clearly shown in Fig. 2. In this way, the fastening element 12 protects the tube against shocks, and twisting of the tube during use of the wheel is prevented. The dowel pin 18 is of the elastic type and is fitted in the tube section in such a manner that it can be removed therefrom and inserted therein at both tube ends depending on the side on which the disc is fixed to the rim, as visible in chain line in Fig. 2. The tubular seat 17 can be painted together with the remaining portion of the wheel whereas the elastic dowel pin is inserted afterwards and can be easily replaced when damaged. The solution involving a removable dowel pin was found to be particularly advantageously exactly because, due to easy substitution of same, it can be readily and quickly replaced when rusted or twisted. At this point it is apparent that the intended purposes have been achieved by providing a varying-track wheel that, by virtue of a centring device of easy, cheap and reliable construction, was found adapted for use also with relatively high speeds, even higher than 50 km/h. In use, changing of the track does not require particular equipment or knowledge by the user, since it is sufficient to unbolt the rim from the plate, select the orientation enabling the desired track to be obtained and bolt the rim to the plate again, positioning the dowel pin into the right end of the tube. Obviously, the above description of an embodiment applying the innovative principles of the present invention is given by way of example only and therefore must not be considered as a limitation of the scope of the invention as herein claimed. For example, the rim and disc shape can vary depending on specific requirements. The fastening elements can also be in the form of a rib or a continuous element along the wheel circumference.

Claims: A varying-track wheel comprising a rim (11) with fastening elements (12) projecting towards the rotation axis of the wheel and a disc (14) peripherally secured in a removable manner to said fastening elements by means of bolts (15), characterised in that it comprises at least two devices (16) for a precise mutual positioning of the disc and rim, each of said devices being operatively disposed close to one of said fastening elements (12) and comprising a tubular seat (17) on the fastening element (12) to removably receive one end of a dowel pin (18) the other end of which projects towards the disc to be fitted into a centring hole (19) formed in the periphery of the disc itself. A wheel as claimed in claim 1, characterised in that the tubular seat is made up of a section of tube (17) welded to the fastening element (12) with its axis parallel to the corresponding bolt (15), and the length of which does not exceed the thickness of the fastening element so that it does not jut out at the two sides thereof. A wheel as claimed in claim 2, characterised in that the dowel pin is of the elastic type fitted in the tube section (17) in such a manner that it can be removed therefrom and inserted therein at both tube ends depending on the side on which the disc is fixed to the rim. A wheel as claimed in claim 1, characterised in that the positioning devices (16) are two in number, disposed on opposite fastening elements (12).

Inventors: SAVIGNAC MICHEL, SAVIGNAC, MICHEL
Applicants: TITAN ITALIA S P A, TITAN ITALIA S.P.A.
Application year: 2001
Main classification: B60B3
IPC codes: B60B23, B60B3