Wheeled work machine

1. A wheeled work machine comprising a traveling body having an engine mounted at a rear part of a machine frame supported by front and rear wheels, and a traveling system power transmission mechanism for transmitting power from said engine to the rear wheels; wherein

said traveling system power transmission mechanism has a rear wheel differential device disposed in front of the engine, a hydrostatic transmission that is disposed in front of the rear wheel differential device and receives power from the engine, and a mechanical transmission device that is disposed between said hydrostatic transmission and said rear wheel differential device and transmits power from said hydrostatic transmission to said rear wheel differential device;

said wheeled work machine further comprising:

a traveling drive shaft extending forward from the engine for receiving power from the engine;

an input shaft extending rearward from the hydrostatic transmission for inputting power from the engine to the hydrostatic transmission; and

an output shaft for outputting power from the hydrostatic transmission,

wherein the traveling drive shaft and the input shaft are coaxially interconnected and extend parallel with the output shaft, and

wherein said engine, said rear wheel differential device, said mechanical transmission device, and said hydrostatic transmission are formed integrally with each other.

2. The wheeled work machine according to claim 1 , wherein

a housing that accommodates said rear wheel differential device is attached and fixed to a front surface of said engine;

a transmission case that accommodates said mechanical transmission device is attached and fixed to a front surface of said housing; and

a casing for said hydrostatic transmission is attached and fixed to a front surface of said transmission case.

3. The wheeled work machine according to claim 2 , wherein said power transmission mechanism has left and right final transmission devices for transmitting power from left and right differential output shafts of said rear wheel differential device to rear wheel axles on same left and right sides; wherein

final transmission cases that accommodate said final transmission devices are attached and fixed to said housing.

4. The wheeled work machine according to claim 3 , comprising a rotation table supported so as to be able to swivel on said traveling body; wherein

a ground implement is provided to a front part of said rotation table; and

a driver seat is provided to a rear part of said rotation table.

5. The wheeled work machine according to claim 4 , said machine frame having:

an upper wall and left and right side walls that extend downward from left and right ends of the upper wall;

an engine positioning part for positioning said engine at a rear part between said left and right side walls;

a travelling power transmission system positioning part for positioning said housing, said transmission case, and said casing in front of said engine between the left and right side walls; and

a bearing positioning part for positioning a swivel bearing for supporting the rotation table in a substantial center position between front and rear axles; wherein

a case fitting part for fitting with the final transmission cases from above is formed at rear parts of said left and right side walls.

6. The wheeled work machine according to claim 1 , wherein a rear wheel axle that receives power from the differential output shafts of said rear wheel differential device and rotates the rear wheels is provided behind the differential output shafts so as to overlap said engine as viewed from the side.

7. The wheeled work machine according to claim 1 , further comprising:

a bevel pinion shaft extending parallel with the output shaft for receiving power from the output shaft;

wherein a rear end of the bevel pinion shaft is positioned more rearward than a rear end of the output shaft, the rear wheel differential device is positioned rearward of the bevel pinion shaft, and power from the output shaft is inputted to the rear wheel differential device via the bevel pinion shaft.

8. The wheeled work machine according to claim 1 , wherein

a rear end of the input shaft protrudes rearward from a rear side of a casing for the hydrostatic transmission; and

a front end of the output shaft protrudes forward from a front side of the casing and a rear end of the output shaft protrudes rearward from the rear side of the casing.