Bombardier Inc.

Jean-Guy Talbot

Roger Rioux

Berthold Fecteau

Willy Bostelmann

Yvon Gagne

Raymond Cote

Gilles Pesant

Andre M Gauthier

Alain Tremblay

This invention relates to an improved snowmobile drive train configuration arrangement that incorporates a fixed ratio speed reduction mechanism directly coupled to the engine crankshaft. This mechanism is in turn coupled to the driving pulley of a variable ratio belt drive system, the driven pulley of which is mounted on the axle of the sprocket wheels that drive the snowmobile track. Interposing the reduction drive between the engine and the belt drive system reduces the operational speed of both the pulleys and the belt, which proves beneficial from several aspects: the mechanical efficiency of the global system is increased, the dynamic response of the transmission to throttle modulation is improved; aerodynamic losses are reduced; the bending vibrations of the crankshaft are no longer transmitted to the drive clutch; and the engine can be run at higher RPM without decreasing the efficiency of the belt drive system.

Snowmobile reduction drive

In a snowmobile drive train the variable ratio belt drive is not directly coupled to the engine crankshaft as in the prior art, but rather the driving pulley of the variable ratio belt drive is carried on one end of a jackshaft and the engine power is applied to the opposite end of the jackshaft. The jackshaft is supported in a fixed bearing in the vehicle frame, this bearing being immediately adjacent to the driving pulley so that the influence on the belt drive of vibrations generated by the engine is vastly diminished. Therefore the engine mounts can be arranged to fully absorb vibrations of the engine. Previously, when the driving pulley was directly coupled to the engine crankshaft it was necessary to include a tie restraint to limit movements of the engine housing in the direction of separation between the axes of the driving and driven pulleys.

Snowmobile transmission jackshaft

In a snowmobile ski suspension each ski is steerable within a bearing support which is connected in the snowmobile on parallelogram suspension linkage means having upper and lower transverse suspension arms pivotally attached to the bearing support. A strut has a lower end pivoted on the lower suspension arm and extends upwardly to act upon a hydraulic damper through a crank lever.

Snowmobile ski suspension

This invention relates to a new or improved snowmobile frame structure which comprises a pair of loop shaped tubular frame members extending forwardly of the track tunnel which are braced by transverse frame members welded thereto and provides support for the snowmobile engine suspension and steering components.

Snowmobile frame structure

Snowmobile track

In a rotary clutch for a snowmobile comprising a movable pulley flange which carries pivotally mounted flyweights operable on rotation of the clutch to effect axial displacement of the movable flange towards a fixed pulley flange, the pivot shafts for the flyweights have previously been retained in mounting lugs on the movable flange by cotter pins or the like. Improper maintenance of such clutches has on occasion led to unorthodox methods of retaining the pivot shafts, such as the use of wire instead of cotter pins, or the replacement of the pivot shaft by a nut and bolt thereby causing severe unbalance in the clutch. To obviate this problem, the pivot shafts are now designed to be retained solely by abutment means formed integrally with the bell housing which attaches to the rear side of the movable flange.

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Valcourt, Canada

Jean-Guy Talbot