Working vehicle with a cab

1. A working vehicle with a cab, comprising:

a vehicle body for supporting said cab;

ground-engaging means for supporting said vehicle body; and a cab frame provided to said cab, said cab frame including right and left front posts, right and left rear posts, an upper front frame extending between the right and left posts, and right and left upper frames extending fore and aft between upper end regions of said front posts and upper end regions of said rear posts, respectively;

wherein at least part of said cab is curved to bulge outward;

wherein each of said right and left upper frames is curved to bulge laterally outward such that a portion of each of the upper frames, that is closer to a longitudinally approximately middle portion thereof, is bulged more laterally outwardly with respect to front and rear ends thereof; and

wherein said upper front frame is curved to bulge upwardly such that a portion of the upper front frame, that is closer to a transversely approximately middle position thereof, is bulged further upwardly with respect to lateral ends of the upper front frame.

2. A working vehicle as defined in claim 1 , wherein each of said right and left front posts is curved to gradually bulge laterally outwardly such that a portion of each of the front posts, that is closer to a vertically approximately middle position of the front post, is displaced more laterally outwardly with respect to vertically opposite ends thereof.

3. A working vehicle as defined in claim 2 , wherein each of said right and left rear posts is curved to bulge laterally outwardly such that a portion of each of the rear posts, that is closer to a lower end of the rear post, is bulged more laterally outwardly with respect to an upper end thereof to correspond in shape to an upper halve of the corresponding front post.

4. A working vehicle as defined in claim 2 , wherein each upper half of said right and left front posts is gradually curved to incline rearwardly such that a higher portion of each of the front posts is displaced more rearwardly.

5. A working vehicle as defined in claim 1 , wherein said cab includes a front windshield having an upper portion curved to bulge forwardly from said upper front frame as it extends downwardly such that a portion of said front windshield below said upper portion is located more forwardly of said upper front frame of said cab frame.

6. A working vehicle as defined in claim 1 , further comprising a reinforcing frame extending between and fixed to said right and left upper frames of said cab frame.

7. A working vehicle as defined in claim 6 , wherein said reinforcing frame includes a pair of legs with each leg extending generally vertically and fixed to corresponding one of said right and left upper frames, and a substantially horizontal portion connected to upper ends of the legs, said reinforcing frame having an upper surface located higher than the highest portion of said upper front frame of said cab frame.

8. A working vehicle as defined in claim 1 , wherein said cab includes right and left inner surfaces, each of which is curved to gradually bulge laterally outwardly such that a portion of each of the inner surfaces, that is closer to a longitudinally approximately middle position of the inner surface, is displaced more laterally outwardly with respect to front and rear ends of the inner surfaces.

9. A working vehicle as defined in claim 1 , wherein said cab includes an inner roof having a lower surface which is curved to gradually bulge upward such that a portion of the lower surface, that is closer to a longitudinally approximately middle portion of the lower surface, is displaced higher than longitudinally end portions of the lower surface.

10. A working vehicle as defined in claim 1 , further comprising:

an air-conditioner body disposed below a driver's seat in a rear position of said cab; a delivery duct for guiding conditioned air outputted from said air-conditioner body,

said delivery duct extending forward from said air-conditioner body along a bottom of said cab;

a steering wheel disposed forwardly of said driver's seat;

an outlet-side duct for discharging the conditioned air from adjacent said steering wheel; and

a relay duct extending between said delivery duct and said outlet-side duct, said relay duct being disposed outside a front surface of said cab.

11. A working vehicle as defined in claim 10 , further comprising:

a front panel acting as a partition between inside and outside of said cab, said front panel being located in a transversely middle region of a lower front portion of said cab frame; and

a pair of upper and lower duct insertion bores formed in said front panel;

wherein said relay duct has an upper end thereof connected to said outlet-side duct through the upper duct insertion bore, and a lower end connected to said delivery duct through the lower duct insertion bore.

12. A working vehicle with a cab, comprising:

a vehicle body for supporting said cab;

ground-engaging means for supporting said vehicle body; and

a cab frame provided to said cab, said cab frame including:

a right front post;

a right rear post;

a right upper frame extending fore and aft between said right front post and said right rear post, and having a forward end connected at a first connection area to an upper end region of said right front post and a rear end connected at a second connection area to an upper end region of said right rear post;

a left front post;

a left rear post;

a left upper frame extending fore and aft between said left front post and said left rear post, and having a forward end connected at a third connection area to an upper end region of said left front post and a rear end connected at a fourth connection area to an upper end region of said left rear post; and

an upper front frame extending between said left front post and said right front post, and having a left end connected at a fifth connection area to said left front post, and a right end connected at a sixth connection area to said right front post, and wherein said upper front frame is curved upward in an arch form, such that the highest part of a lower edge of said upper front frame is located higher than an upper end of each of said right front post and said left front post;

a front windshield extending between said right and left front posts and, when seen from above, projecting forward beyond a straight line linking a front edge of said fifth connection area and a front edge of said sixth connection area;

a right side extending between said right front post and said right rear post and, when seen from above, curved to bulge rightward beyond a right edge of said first connection area and a right edge of said second connection area; and

a left side extending between said left front post and said left rear post and, when seen from above, curved to bulge leftward beyond a right edge of said third connection area and a left edge of said fourth connection area.

13. A working vehicle as defined in claim 12 , wherein each of said right and left sides includes at least one of a door and a window pane.