Endless track for a vehicle

The endless track is made of a reinforced rubber material with longitudinally spaced and transversely disposed ridges or lugs. It is particularly well-adapted for recreational snowmobiles having a single track. The ground-engaging side of the track features a tread pattern that is repeated uniformly or not over the entire length of the track. The tread pattern comprises a plurality of projecting traction lugs each an upper edge having which together delimit the general outline of a cross-sectional transversal traction lug profile when viewed along a longitudinal direction. The track is characterized in that the traction lug profile comprises a substantially flat central or interior section and two opposite exterior or lateral sections located on the sides of the interior section and that taper toward the exterior. Such track facilitates the steering capabilities of a snowmobile, particularly when the snowmobile is travelling on hard and abrasive surfaces. It also improves the durability of the track.

DETAILED DESCRIPTION A track ( 10 ) according to a possible and preferred embodiment of the present invention is described hereinafter and illustrated in the appended figures. As shown in FIGS. 1 and 2 , the track comprises an endless body ( 12 ) made of a reinforced rubber material with longitudinally spaced and transversely disposed stiffeners (not shown) may or may not be embedded in the rubber material. The body defines a longitudinally extending central portion ( 20 ) and a pair of opposite lateral band portions ( 16 , 18 ) each of which is located on one side of the central portion ( 20 ). The body ( 12 ) of the track ( 10 ) has a ground-engaging outer side that is provided with a tread pattern ( 30 ). The tread pattern ( 30 ) is repeated uniformly or not over the entire length of the track ( 10 ). The tread pattern ( 30 ) comprises a plurality of projecting traction lugs ( 42 , 44 , 45 , 46 , 48 ) disposed on the central band portion ( 20 ), on the lateral band portions ( 16 , 18 ) or both. The traction lugs typically have between ¾ and 3 inches in lateral length. The width of the central band portion ( 20 ) is typically in the range of 5 to 10 inches, with a preferred value of 6½ inches when the total width of the track ( 10 ) is 15 inches. Each of the traction lugs ( 42 , 44 , 45 , 46 , 48 ) has an upper edge that together delimit the general outline of a cross-sectional transversal traction lug profile ( 60 ) when viewed along the longitudinal axis of the track. The expression “general outline” refers to the average laterally extending line formed by the upper edges of the lugs, which are often provided with small regular or jagged indentations. This traction lug profile ( 60 ) is shown in FIG. 2 . Now, in accordance with the present invention, the track ( 10 ) is characterized in that the traction lug profile ( 60 ) comprises a substantially flat interior or central section ( 62 ) and two opposite exterior or lateral sections ( 66 , 68 ) each, located on one side of the interior section ( 62 ) and which tapers toward the exterior. The exterior sections ( 66 , 68 ) are preferably straight and symmetrical with reference to a medial axis of the interior section ( 62 ). Alternatively, the interior sections ( 66 , 68 ) are curved and symmetrical with reference to the medial axis of the interior section ( 62 ). Preferably, the exterior sections ( 66 , 68 ) have an average angle ∝ in the range of 10 to 40 degrees with reference to the interior section ( 62 ). Further, the interior section ( 62 ) has a width that is somewhat equal to that of the central band portion ( 20 ) and the exterior sections ( 66 , 68 ) have a width that is somewhat equal to that of the corresponding lateral band portion ( 16 , 18 ). Preferably, each of the exterior sections ( 66 , 68 ) comprises an innermost main subsection ( 66 a , 68 a ) having an average angle ∝ in the range of 10 to 40 degrees with reference to the outline of the interior section ( 62 ), and an outermost tip subsection ( 66 b , 68 b ) having an average angle &bgr; in the range of 40 to 80 degrees with reference to the outline of the interior section ( 62 ). It should be noted that when designing a track ( 10 ) in accordance with the present invention, it is important to have a sufficient angular demarcation between the interior section ( 62 ) and the exterior sections ( 66 , 68 ) so as to create a rotation point that does not make the track ( 10 ) unstable when traveling in a straight course. Thus, the interior section ( 62 ) has to be large enough to adequately support the snowmobile. Although a preferred embodiment of the invention has been described in detail herein and illustrated in the accompanying figures, it is to be understood that the invention is not limited to this precise embodiment and that various changes and modifications may be effected therein without departing from the scope or spirit of the present invention.