Utility vehicle

1. A utility vehicle comprising: a vehicle body frame; a pair of right and left front wheels disposed at a front end of the vehicle body frame; and a pair of right and left rear wheels disposed at a rear end of the vehicle body frame,

wherein the vehicle body frame has, at a bottom thereof, a bottom main frame extending in an anteroposterior direction, the bottom main frame including

a frame front portion located between the pair of right and left front wheels,

a frame rear portion located between the pair of right and left rear wheels, and

a frame intermediate portion located between the frame front portion and the frame rear portion and extending in the anteroposterior direction, the frame intermediate portion including:

a cross member located at a substantially intermediate position between the front wheel and the rear wheel in the anteroposterior direction and extending in the vehicle width direction;

a pair of right and left anteroposterior front members anteroposteriorly coupling the cross member and the frame front portion; and

a pair of right and left anteroposterior rear members anteroposteriorly coupling the cross member and the frame rear portion, wherein:

in a vehicle side view, the bottom main frame has a frame highest portion in the frame intermediate portion, which has a highest ground level in the bottom main frame,

the bottom main frame has a ground level gradually increasing from the frame front portion and the frame rear portion toward the frame highest portion, and

the frame intermediate portion in a side view forms an angular shape that projects upward so as to have a peak at the cross member, so that the cross member is disposed at the frame highest portion.

2. The utility vehicle according to claim 1 , further comprising:

a front wheel gear box supported by the frame front portion;

a front wheel drive shaft supported by the front wheel gear box to transmit driving power to the front wheels;

a rear wheel gear box supported by the frame rear portion; and

a rear wheel drive shaft supported by the rear wheel gear box to transmit driving power to the rear wheels.

3. The utility vehicle according to claim 1 , wherein the level of the frame highest portion is higher than levels of the frame front portion and the frame rear portion, by not less than one inch and not more than two inches.

4. The utility vehicle according to claim 1 , further comprising a pair of right and left trailing arms extending in anteroposterior direction and freely rotatably supporting the respective rear wheels at a rear end the trailing arm, wherein

the trailing arm has a bent portion to project upward so that a rear portion extends in a downwardly slanting direction from the bent portion toward a rear end thereof, and the trailing arm at ahead of the rear wheel is located above the lower face of the anteroposterior rear member in a 1 G state.

5. The utility vehicle according to claim 1 , wherein:

the bottom main frame extends at substantially an intermediate position in the vehicle width direction;

the vehicle body frame further has a pair of left and right bottom side frames located outside thereof in the vehicle width direction;

the left bottom side frame extends in the anteroposterior direction between the left front wheel and the left rear wheel;

the right bottom side frame extends in the anteroposterior direction between the right front wheel and the right rear wheel; and

the pair of the left and right bottom side frames is located above the bottom main frame.

6. The utility vehicle according to claim 2 , wherein:

the frame intermediate portion further includes a front cross member coupling the right and left anteroposterior front members in vehicle width direction;

the front wheel gear box is coupled to a propeller shaft extending forward from the rear of the vehicle so as to transmit driving power, the propeller shaft being divided in the anteroposterior direction into an intermediate propeller shaft, a front propeller shaft located ahead of the intermediate propeller shaft, and a rear propeller shaft located behind the intermediate propeller shaft; and

the front cross member supports a bearing for the intermediate propeller shaft.