A two-seater off-road vehicle includes a travel vehicle body that is supported on the ground by a front wheel unit and a rear wheel unit, and a boarding part disposed above a vehicle body frame included in the travel vehicle body. The boarding part includes: a driver seat; a steering operation tool in front of the driver seat; and a passenger seat of a saddle seat type behind the driver seat.

A power transmission mechanism (2) includes left and right drive shafts (3L, 3R) that transmit rotational torque from a drive source to drive wheels provided on left and right sides of a vehicle. In the right drive shaft (3R) and the left drive shaft (3L), the numbers of rolling elements (23, 33) included in plunging type constant velocity universal joints (6L, 6R) are different from each other.

A propeller shaft as a power transmission shaft is provided between vehicle-side first second shaft parts, and a first tube as a first shaft member is connected to the first shaft part through a first joint member and to the second shaft part through a second joint member. The first tube is connected to the first joint member through a first collar member and to the second joint member through a second collar member. The first collar member includes a first main body part exposed from a first end portion of the first tube, and a first insertion part inserted into the inside of the first end portion. In at least the first collar member, the maximum value of the outer diameter of the first main body part is set to be no greater than the maximum value of the outer diameter of the first insertion part.

A propeller shaft as a power transmission shaft is provided between vehicle-side first second shaft parts, and a first tube as a first shaft member is connected to the first shaft part through a first joint member and to the second shaft part through a second joint member. The first tube is connected to the first joint member through a first collar member and to the second joint member through a second collar member. The first collar member includes a first main body part exposed from a first end portion of the first tube, and a first insertion part inserted into the inside of the first end portion. In at least the first collar member, the maximum value of the outer diameter of the first main body part is set to be no greater than the maximum value of the outer diameter of the first insertion part.

In a coupling structure for a propeller shaft and a propeller shaft, a propeller shaft-side adapter includes: a flange portion of the propeller shaft-side adapter extending in a radial direction relative to a rotation axis of a rotation shaft, and connected to a flange portion of a vehicle-side adapter; a center pin accommodating portion formed on the rotation axis, and into which a center pin provided to the vehicle-side adapter is inserted; and an inner peripheral portion formed between the flange portion of the propeller shaft-side adapter and the center pin accommodating portion in the radial direction relative to the rotation axis, which is opposed to the vehicle-side adapter in a direction of the rotation axis, and in which a distance from the rotation axis in the radial direction relative thereto decreases extending away from the flange portion of the vehicle-side adapter in the rotation axis direction.

A vehicle drive train assembly includes a propeller shaft and a nut. The nut has a first part and a second part. The first part is movable with respect to the propeller between an uninstalled position and an installed position of the nut. The second part is stationary with respect to the propeller shaft in the uninstalled position and the installed position.

A vehicle drive train assembly includes a propeller shaft and a nut. The nut has a first part and a second part. The first part is movable with respect to the propeller between an uninstalled position and an installed position of the nut. The second part is stationary with respect to the propeller shaft in the uninstalled position and the installed position.

An all-wheel system for a motor vehicle, with a first electric machine for driving a first drive axle of the motor vehicle; a first electronic power unit for controlling a rotational speed of the first electric machine; a second electric machine for driving a second drive axle of the motor vehicle; a second electronic power unit for controlling the rotational speed of the second electric machine on the basis of the rotational speed of the first electric machine and a specified differential rotational speed between the first electric machine and the second electric machine.

An all-wheel system for a motor vehicle, with a first electric machine for driving a first drive axle of the motor vehicle; a first electronic power unit for controlling a rotational speed of the first electric machine; a second electric machine for driving a second drive axle of the motor vehicle; a second electronic power unit for controlling the rotational speed of the second electric machine on the basis of the rotational speed of the first electric machine and a specified differential rotational speed between the first electric machine and the second electric machine.

An attachment structure of a generator and a working machine including a transmission case; and a PTO shaft protruding from the transmission case, includes a structure body attached to a side of the transmission case from which the PTO shaft protrudes, and includes the generator attached to the structure body.