1. Field of the Invention
The present invention relates to a snowmobile ski, and particularly, a snowmobile ski having an offset runner and keel and a snowmobile ski having longitudinally extending snow compacting ribs.
2. Description of Related Art
In designing snowmobile skis, there are several performance criteria, which are deemed to be important. These include, inter alia, maneuverability, steerability, stability, flotation, and side-hilling capability. xe2x80x9cManeuverabilityxe2x80x9d is also referred to as xe2x80x9caggressivityxe2x80x9d in the industry and describes the ability of the skis to provide an effective and superior handling/steering of the sled in response to the turning of the steering bar of the snowmobile. xe2x80x9cSteerabilityxe2x80x9d refers to the relative ease with which the sled can be steered with the skis. By definition, a set of skis is easy to steer when the resistance to the steering is kept minimal. xe2x80x9cStabilityxe2x80x9d addresses the pitching and darting tendency of the snowmobile skis during the ride. Rather than being aligned in the intended direction without much wavering, snowmobile skis may pitch and dart, thereby requiring frequent adjustments of the steering system in order to steer the skis and the sled in the intended driving direction. xe2x80x9cFloatationxe2x80x9d refers to the performance of the skis on powder snow (as opposed to compact trails or ice) which allows the sled to be propelled over snow. In such applications as mountain snowmobiles, superior floatation characteristics are essential, as the snowmobile will often be driven on deep fresh powder snow. Finally, xe2x80x9cside-hilling capabilityxe2x80x9d refers to the performance of the snowmobile skis, typically on mountain snowmobiles, when the sled climbs a hill by traversing diagonally up the hill in a zigzag fashion. In side-hilling, the snowmobile is tilted in the direction of the turn, and as a result, the ski on the tilted side tends to be relied upon more heavily than the ski on the other side during each turn. In instances where the skis have poor side-hilling capabilities, the snowmobile may slip laterally because not enough snow is engaged by the skis when tilted on one side.
Depending on the intended application of the snowmobiles, the particularities of the designs of the snowmobile skis or the methods of attaching the skis to the snowmobile can be varied so as to optimize the desired performance characteristics of the skis. Indeed, prior patents illustrate numerous examples of attempts to improve desirable characteristics of the snowmobile skis.
For example, U.S. Pat. No. 5,038,882 (the xe2x80x9c""882 patentxe2x80x9d) shows a conventional snowmobile ski which comprises a ski liner adopted to be connected to a bridge on its top surface, a keel disposed longitudinally along the bottom snow-contacting surface of the ski liner, and a runner (also referred to as a xe2x80x9cwear rodxe2x80x9d in the art) disposed on the keel. The bridge connected to the ski liner""s top surface is adopted to connect to the ski leg of the snowmobile. The ski shown in the ""882 patent is typical of conventional skis in that the keel extends longitudinally along the middle of the ski bottom surface. The ""882 patent states that a more comfortable ride can be obtained by a spindle arrangement which offsets its longitudinal axis from the ball joints connected to each spindle. Such offset spindle arrangement, according to the ""822 patent, induces the ski to xe2x80x9ctoe-outxe2x80x9d thereby providing improved stability, i.e., less pitching and darting.
In other examples, U.S. Pat. Nos. 5,040,818 and 5,145,201 disclose a snowmobile ski having a plurality of concave surfaces extending along the snow contacting bottom surface of the ski. The ski shown in these two patents has a center concave surface extending along the middle of the ski and two concave steering surfaces, which is recessed from the center concave surface. The ""818 and ""201 patents state that the plurality of concave portions provides floatation by compacting snow and lifting the ski and that the lateral recessed steering portions provide better stability and control as the ski turns. However, the center concave surface extends on the bottom surface of the keel, which longitudinally extends along the middle of the ski, as done in other conventional skis. Similarly, while U.S. Pat. No. 3,643,979 shows a snowmobile ski having recessed lateral surfaces or stepped portions, the ski in the ""979 patent also has a runner and a keel longitudinally extending along the middle of the ski in a conventional manner.
While snowmobile skis disclosed in the aforementioned patents have keels and runners longitudinally extending along the middle of the skis, several other prior patents disclose snowmobile skis with the keels or runners at the lateral sides of the skis, thereby forming a shape of a tunnel or channel. For example, U.S. Pat. Nos. 3,734,221 and 3,817,544 disclose a snowmobile ski having a longitudinally extending central groove that creates a concave shape. The runners are provided on both sides of the groove, and the central groove is said to provide improved steerability. Finally, U.S. Pat. No. 5,836,594 discloses a double-keel snowmobile ski having the keels extending down from the two lateral edges of a flat middle portion of the ski liner, wherein vertically and horizontally extending wedges are provided at the longitudinal ends of the keel and a concave front portion of the ski liner is provided to funnel the snow to the middle portion of the ski liner. According to the ""594 patent, a snowmobile ski with the double-keel arrangement disclosed therein enhances floatation, efficient turning, and smooth forward and reverse movement.
These and other prior art snowmobile skis heretofore are available, however, do not teach or suggest a snowmobile ski having an offset runner and keel with longitudinally extending snow compacting ribs disposed slanting upward from the keel toward the inner lateral edge of the ski. Snowmobiles skis having these features in accordance with the present invention provide improved performance characteristics beneficial for use in mountain snowmobiles as well as touring type snowmobiles.
It is an object of the present invention to provide a novel snowmobile ski with improved performance characteristics for use in both powder snow applications (which is generally beneficial for mountain snowmobiles) and trail applications (which is generally beneficial for touring snowmobiles). It is a further object of the present invention to provide a snowmobile ski with excellent maneuverability, stability, steerability, floatation and side-hilling characteristics.
It is an aspect of the present invention to have a ski body with an inner lateral edge, an outer lateral edge, a top surface, a bridge integrally molded with the top surface, and a bottom surface adapted for moving over snow. The inner lateral edge is defined as being the edge, which faces towards the centerline of the snowmobile and the outer lateral edge is defined as being the edge which faces away from the centerline of the snowmobile.
According to an aspect of the present invention, a snowmobile ski has a bridge adapted to connect to a ski leg of a snowmobile, and the ski body with the inner lateral edge and the outer lateral edge. The top surface of the ski body is adapted to be connected the bridge, and the bottom surface of the ski body is adapted for moving over snow.
A single keel is provided lengthwise along the bottom surface of the ski body in such a manner that a centerline of the keel is offset from a centerline of the bridge in a direction toward the outer lateral edge of the ski body. Finally, a runner is connected to the keel on one axial side of the ski body.
Another aspect of the present invention provides a snowmobile ski with a longitudinally extending rib arranged on the snow contacting bottom surface of the ski body between the inner lateral edge of the ski body and the keel, which is disposed lengthwise along the bottom surface of the ski body in such a manner that a longitudinal axis of the keel is offset from a longitudinal axis of the bridge in a direction toward the outer lateral edge of the ski body.
In accordance with yet another aspect of the present invention, a snowmobile ski has a plurality of longitudinally extending snow compacting channels arranged on the bottom surface of the ski body. In the preferred embodiment, each of these snow compacting portions extend from the ski body to different levels, but as illustrated in a second embodiment, the compacting portions could be situated at the same level. When viewed cross-sectionally along the transverse direction of the ski, the preferred arrangement of the snow compacting portions are arranged such that the bottom surface of the ski is generally inclined in a direction from the keel toward the inner lateral edge.
It is still yet another aspect of the present invention that a snowmobile ski has a ski body with an inner lateral edge and an outer lateral edge where the snowmobile ski has a keel which extends downwardly from the bottom surface of the ski body at the outer lateral edge and only one runner which is attached to the keel.
According to another aspect of the invention, a snowmobile ski has a ski body with an integrally molded bridge. The integrally molded bridge is adapted to be connected to a ski leg of a snowmobile. Also molded into the bridge are indentations to accept steel bushings, which are press-fitted into the indentations to ensure a solid surface between the ski body and the ski-leg. The bushing are designed such that head of the nut and bolt holding the ski-leg to the bridge do not increase the width of the ski. A single keel is provided lengthwise along the bottom surface of the ski body in such a manner that a centerline of the keel is offset from a centerline of the bridge and or the centerline of the ski width, in a direction toward the outer lateral edge of the ski body. The centerline of the ski is determined by a line, which separates the ski body in a left side and a right of the same width. Finally, a runner is connected to the keel on one axial side of the ski body.
In another aspect of the invention, along each side of the longitudinal rib disposed on the bottom surface of the ski body is defined snow compacting portions which extend from the ski body at different levels, such that when viewed cross sectionally, the bottom surface of the ski generally inclines in a direction from the keel toward the inner lateral edge.
A flat section between the keel and the outside lateral edge of the ski improves maneuverability and reduces snow projection.
Other objects and advantages of the present invention will be apparent from the appended claims and understood from the following detailed description of the present invention and the following drawings.