Snowmobile planetary drive system

1. A snowmobile comprising:

(a) a continuously variable transmission having a driven pulley;

(b) a snowmobile track drive sprocket;

(c) a forwardly mounted engine having a drive shaft coupled to the driven pulley by means of a drive belt;

(d) a rearwardly extending tunnel comprising a top panel and two side panels;

(e) a first shaft including a first sun gear and a second sun gear adjacent the first sun gear, the driven pulley being coupled to the first shaft;

(f) a second shaft, the snowmobile drive sprocket being coupled to the second shaft;

(g) a first planetary assembly including a plurality of first planetary gears and a first cage supporting the plurality of first planetary gears, wherein the plurality of first planetary gears is driven by the first sun gear;

(h) a second planetary assembly including a plurality of second planetary gears and a second cage supporting the plurality of second planetary gears, wherein the plurality of second planetary gears are driven by the second sun gear;

(i) a first ring gear connected to the second shaft wherein rotation of the first ring gear at a first rate of rotation causes rotation of the second shaft at the first rate of rotation, and wherein the first ring gear is capable of being driven by the plurality of first planetary gears;

(j) a second ring gear wherein the second ring gear meshes with the plurality of second planetary gears;

(k) a first locking device engagable with the first cage to releasably lock the first cage in a fixed rotated position; and

(l) a second locking device engagable with the second ring gear to releasably lock the second ring gear in a fixed rotated position; and

(m) a housing mounted to one of the two side panels, the housing at least partially encasing the first and second sun gears and first and second planetary assemblies.

2. The snowmobile of claim 1 wherein the first second cage is coupled between the first ring gear and the second shaft.

3. The snowmobile of claim 1 , wherein the first and second shafts are coaxial, and wherein at least one of the first and second shafts includes a weight-bearing protrusion projecting within an end of the other of the first and second shafts, a bearing being positioned on the weight-bearing protrusion between the first and second shafts.

4. The snowmobile of claim 1 , wherein the one of the two side panels to which the housing is mounted at least partially encases the first and second sun gears and the first and second planetary assemblies.

5. A snowmobile comprising:

(a) a frame including a tunnel;

(b) an engine secured to the frame forward of the tunnel, the engine having a drive shaft extending therefrom;

(c) a track coupled to the tunnel;

(d) a track shaft coupled to the tunnel and to the track for driving the track;

(e) a continuously variable transmission coupled between the drive shaft and the track shaft; and

(f) a planetary gear assembly including a housing, an input shaft, an output shaft, a plurality of planetary gears, and a ring gear; the input shaft including a sun gear, the sun gear being coupled to the plurality of planetary gears which are in turn coupled to the ring gear, the planetary gears being held at their axes by a cage, the cage and ring gear each being selectively fixed relative to the housing; wherein the planetary gear assembly is coupled between one of (i) the drive shaft and the continuously variable transmission and (ii) the continuously variable transmission and the track shaft on the same side of the tunnel as the continuously variable transmission.

6. The snowmobile of claim 5 , wherein the continuously variable transmission includes a driven pulley coupled to the drive shaft with a belt, the driven pulley being secured to a driven shaft; and wherein the planetary gear assembly is coupled to the driven shaft and to the track shaft.

7. The snowmobile of claim 6 , wherein the input shaft includes an input gear extending outwardly from one end thereof, the snowmobile further comprising an offsetting gear coupling the driven shaft to the input gear.

8. The snowmobile of claim 1 , wherein the input and output shafts are coaxial, and wherein at least one of the input and output shafts includes a weight-bearing protrusion projecting within an end of the other of the first and second shafts, a bearing being positioned on the weight-bearing protrusion between the first and second shafts.

9. A snowmobile comprising:

(a) a frame including a tunnel;

(b) an engine secured to the frame forward of the tunnel, the engine having a drive shaft extending therefrom;

(c) a track coupled to the tunnel;

(d) a track shaft coupled to the tunnel and to the track for driving the track;

(e) a continuously variable transmission coupled between the drive shaft and the track shaft, the continuously variable transmission including a driven pulley coupled to the drive shaft by a belt; and

(f) a planetary gear assembly including a housing, an input shaft with a sun gear, an output shaft, a plurality of planetary gears, and a ring gear coupled together; the planetary gears being held at their axes by a cage, the cage and ring gear each being selectively fixed relative to the housing; wherein the planetary gear assembly is coupled between the driven pulley and the track shaft on the same side of the tunnel as the driven pulley.

10. The snowmobile of claim 9 , wherein the input and output shafts are coaxial, and wherein at least one of the input and output shafts includes a weight-bearing protrusion projecting within an end of the other of the first and second shafts, a bearing being positioned on the weight-bearing protrusion between the first and second shafts.