Patent ID: 8043179

Claim:
A drive chain adjustment mechanism of a chain-driven vehicle chain-driving two rear wheels, the chain-driven vehicle being adapted to drive the rear wheels with a drive chain and a driven sprocket around which the drive chain is wound, and to move the driven sprocket in a fore and aft direction of a vehicle body, thereby adjusting tension of the drive chain, wherein the rear wheels are suspended right and left independently of each other with a pair of axle shafts individually held by a pair of outer rings, the driven sprocket is fixed to one of the outer rings, the pair of outer rings is rotatably supported by a cylinder portion of a case with a bearing, the case includes the cylinder portion, a first support portion and a second support portion, the first support portion being extended rearward from the cylinder portion and supported on the vehicle body by a tip end thereof extended in a right and left direction of the vehicle body, the second support portion being extended forward from the cylinder portion and supported on the vehicle body by a tip end thereof, the first support portion is attached to a support bracket of the vehicle body together with a cam with a bolt, and is thus coupled to the vehicle body with the bolt at a position rearward of a shaft portion of the driven sprocket, the support bracket including a long hole long in the fore and aft direction and a pin provided in front of the long hole, the cam moving the case in the fore and aft direction with respect to the vehicle body while changing a position where the cam abuts on the pin on an outer circumferential surface thereof, the bolt being inserted into the long hole and movable in the fore and aft direction with respect to the vehicle body, the second support portion has a long hole which allows the case to move in the fore and aft direction with respect to the vehicle body, the cam includes a pair of the cams provided on both sides of the first support portion in the right and left direction of the vehicle body, and the drive chain is disposed between the pair of cams in the right and left direction of the vehicle body.