Suspension system for snowmobiles

Claim 1

Track suspension means for vehicles having endless track drive and support surfaces, and comprising: a. frame means for said vehicle, and track suspension means coupled thereto at longitudinally spaced forward and rear mounting points, with the endless track having a longitudinal axis; b. said track suspension means including longitudinally flexible leaf spring means having an axis disposed generally parallel to the axis of the endless track and adapted to flex vertically about said spring axis, said leaf spring means being coupled at its forward end to said frame at said forward mounting point; c. a plurality of track running support means secured to said leaf spring means at spaced points along the longitudinal axis thereof; d. said track suspension means including forwardly and rearwardly disposed sprockets inscribed within said endless track to form upper and lower track spans, sprocket mounting means including mounting shaft means for said sprockets, track propelling means and track tensioning means coupled to said forwardly and rearwardly disposed sprockets, said leaf spring means being generally convex to the lower span of said endless track and being coupled at its rearward end to the mounting means for said rearwardly disposed sprocket; e. pivot linkage means coupling said rear sprocket mounting means to said rear frame mounting point, said pivot linkage means including a first arm pivotally coupled at one end to said rear frame mounting point and with a floating pivot shaft journaled to the other end thereof, a second arm having one end journaled to said floating pivot shaft and with the other end thereof coupled to the mounting shaft means for said rearwardly disposed sprockets; and f. resilient spring bias means coupled to said second arm and normally urging said mounting shaft means for said rearwardly disposed sprockets toward the lower span of said endless track.