Snowmobile ski dampener
An improved snowmobile ski dampener for dampening articulation between a steering spindle and a snowmobile ski. The ski dampener may be constructed of an elastomeric material and include one or more progressive surfaces that progressively come in contact with a base surface of the steering spindle as progressively increased compressive loads are applied between the steering spindle and snowmobile ski. As the progressive surfaces come in contact with the base surface, the shape factor of the ski dampener may change (e.g., increase), reducing compressive strain for a given compressive stress. Various design and material characteristics including width, shape of the progressive surface, and durometer and bulk modulus of the elastomeric material may be selected to provide various performance characteristics such as dampening effect, impact absorption, approach angle, initial flex force, and service life.
1. An elastomeric dampener for dampening articulation between a steeling spindle and a ski of a snowmobile, comprising:
a first preload surface forward of an articulation axis between the steering spindle and the ski when the elastomeric dampener is installed between the steering spindle and the ski, the first preload surface in contact with a first surface of one of the steering spindle or the ski when the steering spindle and the ski are in a preload condition; and
a first progressive surface, the first progressive surface forward of the first preload surface and not in contact with the first surface of the one of the steering spindle or the ski when the steering spindle and the ski are in the preload condition, wherein the first surface of the one of the steering spindle or the ski contacts at least a portion of the first progressive surface in a first load condition of the steeling spindle and the ski, the first load condition imparting a compressive load to the elastomeric dampener between the ski and the steering spindle.
2. The elastomeric dampener of claim 1 , wherein, for a plurality of progressively increasing load conditions between the ski and the steering spindle, the portion of the first progressive surface in contact with the first surface of the steering spindle increases.
3. The elastomeric dampener of claim 1 , wherein, in the preload condition, the elastomeric dampener has a first shape factor and in the first load condition the elastomeric dampener has a second shape factor that is higher than the first shape factor.
4. The elastomeric dampener of claim 1 , wherein the elastomeric dampener comprises:
a second preload surface, the second preload surface in back of the articulation axis of the steering spindle and in contact with a second surface of the one of the steering spindle or the ski when the steering spindle and the ski are in the preload condition;
a second progressive surface, the second progressive surface in back of the second preload surface and not in contact with the second surface of the one of the steering spindle or the ski when the steering spindle and the ski are in the preload condition, wherein the second surface of the one of the steeling spindle or the ski contacts at least a portion of the second progressive surface in a second load condition of the steering spindle and the ski, the second load condition imparting a compressive load to the elastomeric dampener between the ski and the steering spindle.
5. The elastomeric dampener of claim 4 , wherein, for a plurality of progressively increasing reverse load conditions, the portion of the second progressive surface in contact with the second surface of the one of the steering spindle or the ski increases, the plurality of progressively increasing reverse load conditions imparting progressively increasing compressive loads to the elastomeric dampener between the ski and the steering spindle.
6. The elastomeric dampener of claim 1 , wherein, in the preload condition, the first preload surface and the first progressive surface are non-coplanar surfaces.
7. The elastomeric dampener of claim 1 , wherein, in the preload condition, the first progressive surface comprises a curvilinear surface.
8. The elastomeric dampener of claim 1 , wherein, in the preload condition, the first progressive surface comprises a plurality of stepped surfaces.
9. The elastomeric dampener of claim 1 , wherein, in the preload condition, the first progressive surface comprises at least one inflection point.
10. The elastomeric dampener of claim 1 , wherein the elastomeric dampener is formed from a urethane elastomer.
11. The elastomeric dampener of claim 1 , wherein the elastomeric dampener is formed from a rubber.
12. The elastomeric dampener of claim 1 , wherein the elastomeric dampener is formed from an elastic polymer.
13. The elastomeric dampener of claim 12 , wherein the elastic polymer is homogenous.
14. The elastomeric dampener of claim 12 , wherein the elastic polymer comprises two or more elastic polymers having at least one different characteristic.
15. The elastomeric dampener of claim 1 , wherein the elastomeric dampener is cast molded or injection molded.
16. The elastomeric dampener of claim 1 , wherein, in the preload condition, the elastomeric dampener comprises a surface discontinuity between the first preload surface and the first progressive surface.
17. The elastomeric dampener of claim 16 , wherein, in the preload condition, the surface discontinuity is behind a front edge of the first surface of the one of the steering spindle or the ski.
18. The elastomeric dampener of claim 1 , wherein the elastomeric dampener comprises a plate, the plate between a first portion of the elastomeric dampener and a second portion of the elastomeric dampener.
19. The elastomeric dampener of claim 18 , wherein the first portion of the elastomeric dampener comprises a first elastic polymer and the second portion of the elastomeric dampener comprises a second, different elastic polymer.
20. The elastomeric dampener of claim 18 , wherein the plate is a rigid plate.