Patent ID: 7413515

Claim:
A drive shaft for ATVs which is installed in a vehicle designed to traverse uneven terrains and which transmits drive power to the wheels through constant velocity joints on the inboard and outboard sides, the drive shaft comprising: a double offset type constant velocity joint used on the inboard side; and an undercut free type constant velocity joint used on the outboard side, wherein the undercut free type constant velocity joint includes an inner joint member having a spherical outer peripheral surface that includes a plurality of bottom-curved track grooves, wherein the ratio of the pitch circle diameter (PCD) of the double offset type constant velocity joint to the ball diameter (d), which is determined by the equation PCD/d=r 1 , is in the range 3.0<r 1 <3.2, wherein the undercut free type constant velocity joint includes an outer joint member having a plurality of bottom-curved track grooves defined therein opposite to the plurality of bottom-curved track grooves of the inner joint member, the plurality of bottom-curved track grooves of the outer joint member and the plurality of bottom-curved track grooves of the inner joint member defining a corresponding plurality of wedge shaped ball tracks, and wherein the wedge shape is wider on the inboard side relative to the outboard side.