Kit for converting conventional motorcycle into snowmobile

Claim 2

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for detachably receiving thereon a conventional motorcycle frame and power unit and adapted to normally support said motorcycle frame and power unit in a perpendicular attitude with respect to the track frame; d. primary drive means including a portion mounted on said mounting beam and pivotal therewith and adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; and e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation.

Claim 3

The combination according to claim 1, in which said track frame includes track guide means including elongated runners having wheels on opposite ends thereof rollably engaging the endless track means adjacent said sprocket means, said track guide means being resiliently mounted on the track frame in operative association with each endless track means to retain a major portion of the lower reach of the track means straight and flat for a major portion of its length between said sprocket means mounted on opposite ends of said track frame.

Claim 4

The combination according to claim 1, in which said primary drive means includes a universal joint one portion of which maintains a constant attitude in relation to the track assembly, while the other portion thereof maintains a constant attitude in relation to the motorcycle mounting beam, whereby in all attitudes of said motorcycle mounting beam, motive power is deliverable to said endless track means to propel the snowmobile over the snow.

Claim 5

The combination according to claim 1, in which torsion means are provided interposed between said motorcycle mounting beam and said track frame.

Claim 6

The combination according to claim 1, in which said motorcycle mounting beam is pivoted at its forward end below and adjacent the forward end of the track frame and pivoted at its aft end above and adjacent the aft end of the track frame.

Claim 7

The combination according to claim 1, in which said ski means includes two sets of brackets detachably secured on said fork structure, a forK extender post detachably secured to said fork structure by said brackets, and a ski pivotally mounted on the lower end of said fork extender post and adapted to engage the snow in front of said track frame.

Claim 8

The combination according to claim 1, in which said drive assembly includes a main drive shaft journaled for rotation on said track frame, a driven sprocket on said main drive shaft, an auxiliary drive shaft mounted on said track frame parallel to said main drive shaft and having a sprocket keyed thereto and connected by a chain to said driven sprocket on the main drive shaft, a stub shaft rotatably supported on said mounting beam and normally axially aligned with said auxiliary drive shaft but pivotable with said mounting beam to effect disalignment therebetween, a universal joint operatively interposed between said auxiliary drive shaft and said stub shaft to lock the two shafts for rotation together despite said disalignment, a sprocket on said stub shaft to effect rotation thereof, and means interconnecting said last mentioned sprocket to said power unit to drive said drive assembly.

Claim 9

The combination according to claim 1, in which brake means are associated with said drive assembly operable to stop rotation of said endless track means.

Claim 10

The combination according to claim 1, in which said track frame comprises a rigid generally rectangular framework fabricated from spaced from spaced and parallel longitudinally extending tubular steel stringers having welded thereacross at intervals a plurality of tubular steel cross-beams, said sprocket means being journaled in relation to said frame so that the upper reaches of said endless tracks always lie in substantial planar alignment with the upper surface of said frame while the lower reaches of said endless tracks always depend below said frame, and means disposed between the lower reaches of said tracks and said frame to retain the lower reaches always spaced below said frame.

Claim 11

The combination according to claim 1, in which said sprocket means includes one set thereof mounted on said track frame for pivotal movement in relation thereto, while a remaining set thereof at the other end of the track frame are restrained from pivotal movement in relation to the track frame, the pivotally mounted sprocket means being associated with the forward end of the track frame and functioning to absorb impact shocks delivered to the forward end of the track frame during use.

Claim 12

The combination according to claim 10, in which the pivot point of said set of sprockets which are pivotally mounted on the track frame is selectively adjustable longitudinally of the track frame to effect adjustment of the tension of said endless track means.

Claim 13

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for receiving thereon a motorcycle frame and adapted to normally support said motorcycle frame in a perpendicular attitude with respect to the track frame; d. primary drive means adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation; and f. a torsion bar assembly operatively interposed between said pivoted motorcycle mounting beam and said track frame and including bracket means selectively adjustable to vary the effective length of the torsion bar to vary the amount of force required to pivot the motorcycle mounting beam in relation to the track frame.

Claim 14

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for receiving thereon a motorcycle frame and adapted to normally support said motorcycle frame in a perpendicular attitude with respect to the track frame; d. primary drive means adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation; and f. a torsion bar assembly operatively interposed between said pivoted motorcycle mounting beam and said track frame and including bracket means selectively adjustable to vary the effective length of the torsion bar to vary the amount of force required to pivot the motorcycle mounting beam in relation to the track frame.

Claim 15

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for receiving thereon a motorcycle frame and adapted to normally support said motorcycle frame in a perpendicular attitude with respect to the track frame; d. primary drive means adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation; and f. said motorcycle mounting beam being pivoted to said track frame along an axis which is inclined to the surface on which the snowmobile is operating.

Claim 16

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for receiving thereon a motorcycle frame and adapted to normally support said motorcycle frame in a perpendicular attitude with respect to the track frame; d. primary drive means adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation; and f. said motorcycle mounting beam being pivoted to said track frame along an axis which is inclined to the surface on which the snowmobile is operating.

Claim 17

The combination according to claim 13, in which said axis about which the mounting beam is pivotable, when extended, intercepts the surface on which the snowmobile is operating at a point ahead of said track frame.

Claim 18

The combination according to claim 13, in which said axis about which the mounting beam is pivotable, when extended, intercepts said steering axis when extended at substantially said point of interception of the steering axis by the surface on which said ski is operating.

Claim 19

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for receiving thereon a motorcycle frame and adapted to normally support said motorcycle frame in perpendicular attitude with respect to the track frame; d. primary drive means adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation; f. said motorcycle mounting beam being pivoted at its forward end below and adjacent the forward end of the track frame and pivoted at its aft end above and adjacent the aft end of the track frame; and g. torsion means having a longitudinal axis coincident with an axis extending through the fore and aft pivot points of said mounting beam, one end of said torsion means being secured to said track frame and an intermediate portion of said torsion means being secured to said mounting beam.

Claim 20

In a conversion kit for converting a conventional motorcycle having a frame, a power unit and a steering assembly including a fork structure pivotal about a steering axis, into a snowmobile, a. a track assembly including a track frame, sprocket means mounted on opposite ends of said track frame and associated with opposite sides thereof, and endless track means rotatably supported on said sprocket means and operable to propel the track assembly over snow; b. a drive assembly mounted on said track frame and operatively connected to said endless track means to selectively effect rotation thereof when said drive assembly is driven; c. a mounting beam pivotally mounted on said track frame for receiving thereon a motorcycle frame and adapted to normally support said motorcycle frame in perpendicular attitude with respect to the track frame; d. primary drive means adapted for interconnection between the drive assembly and the power unit of said motorcycle to effect driving of said drive assembly and selective rotation of said endless tracks; e. ski means adapted to be mounted on the fork structure of the motorcycle and positioned ahead of said track frame for engagement with the snow to effect steering while in operation; f. said motorcycle mounting beam being pivoted at its forward end below and adjacent the forward end of the track frame and pivoted at its aft end above and adjacent the aft end of the track frame; and g. torsion means having a longitudinal axis coincident with an axis extending through the fore and aft pivot points of said mounting beam, one end of said torsion means being secured to said track frame and an intermediate portion of said torsion means being secured to said mounting beam.