US 5,685,387 A · Snowmobile reduction drive

Abstract

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.

Claims13

Dependent claims

A snowmobile comprising:

a frame having a forward end supported on steerable ski means and a rearward end supported on an endless drive track;
an engine mounted in said frame, said engine having a output that is connected via a drive train to deliver propulsion power to said drive track;
said drive train comprising a speed reduction mechanism that is carried on said engine and is drivingly connected to said engine output, said speed reduction mechanism having an output member that is drivingly connected to an input of a variable ratio belt drive transmission system, said variable ratio belt drive transmission system having a driving pulley that is journalled in said frame, and a driven pulley that is coupled to said drive track to deliver the propulsion power thereto.

A snowmobile comprising:

a frame having a forward end supported on steerable ski means and a rearward end supported on an endless drive track;
an engine mounted in said frame, said engine having an output that is connected via a drive train to deliver propulsion power to said drive track;
said drive train comprising
a speed reduction mechanism that is carried on said engine and is drivingly connected to said engine output, said speed reduction mechanism having an output member that is drivingly connected to an input of a variable ratio belt drive transmission system;
said variable ratio belt drive transmission system comprising:
a drive belt looped around a driving pulley and a driven pulley;
a speed responsive mechanism operatively connected to said driving pulley and adapted to effect a progressive variation in the drive ratio of said transmission as the speed of rotation of the driving pulley is altered;
and
a torque sensing mechanism on the driven pulley being operative to effect a progressive variation in the drive ratio as a function of the torque transmitted through the said driven pulley, wherein said driven pulley is coupled, without interposition of any further speed change mechanism, to a transverse axle that is rotatably mounted in said snowmobile frame, said transverse axle carrying drive means which forms a driving engagement with said track belt.

6 more elements

Dependencies are inferred from the claim text.

Snowmobile reduction drive

Life of this patent

Snowmobile reduction drive

Life of this patent

Abstract

Claims13