Abstract:
A cooling structure for a working vehicle with a transmission disposed rearwardly and downwardly of a driver&#39;s seat and having a hydrostatic transmission, and an air-cooled engine disposed rearwardly of the transmission. The cooling structure comprising a fan for cooling the engine and a fan for cooling the transmission mounted on a rotary shaft operatively connecting the transmission with an output shaft of the air-cooled engine, the fans being configured such that air flows generated by the fans move from adjacent the transmission toward the engine; an oil cooler for cooling fluid supplied to the hydrostatic transmission, the oil cooler being disposed between the fan for cooling the engine and the fan for cooling the transmission, and disposed to face each of the fans; and an air guiding plate disposed at a position higher than the oil cooler for guiding air to regions of the fans.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to a cooling structure for a working vehicle having an oil cooler. 
         [0002]    A known cooling structure for a working vehicle having a water-cooled engine includes a cooling fan driven by the engine for cooling a radiator. Cooling air flows generated by the cooling fan are supplied to the radiator and an oil cooler opposed to the radiator to cool oil (see JP 2007-9825, for example). 
         [0003]    In the above construction, the working vehicle has the water-cooled engine requiring many accessories such as the radiator and a water pump. Thus, the working vehicle tends to become large and costly. 
       SUMMARY OF THE INVENTION 
       [0004]    The object of this invention is to provide a cooling structure for cooling oil without increasing the size and cost of a working vehicle. 
         [0005]    A cooling structure for a working vehicle, according to this invention, with a transmission disposed rearwardly and downwardly of a driver&#39;s seat and having a hydrostatic transmission, and an air-cooled engine disposed rearwardly of the transmission, comprises a fan for cooling the engine and a fan for cooling the transmission mounted on a rotary shaft operatively connecting the transmission with an output shaft of the air-cooled engine, the fans being configured such that air flows generated by the fans move from adjacent the transmission toward the engine; an oil cooler for cooling fluid supplied to the hydrostatic transmission, the oil cooler being disposed between the fan for cooling the engine and the fan for cooling the transmission, and disposed to face each of the fans; and an air guiding plate disposed at a position higher than the oil cooler for guiding air to regions of the fans. 
         [0006]    With this characteristic construction, instead of installing a water-cooled engine which requires many accessories such as a radiator and a water pump, oil stored in the change speed devices and oil passing through the oil cooler can be cooled by cooling air flows generated by the fan for cooling the change speed devices. 
         [0007]    Therefore, the oil can be cooled without increasing the size and cost of the working vehicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side elevation of a riding type mowing machine; 
           [0009]      FIG. 2  is a side view in vertical section of a principal portion showing a cooling structure; 
           [0010]      FIG. 3  is a side view in vertical section of the principal portion showing a maintenance state; 
           [0011]      FIG. 4  is a plan view in cross section of the principal portion showing the cooling structure; 
           [0012]      FIG. 5  is a rear view in vertical section of the principal portion showing the cooling structure; 
           [0013]      FIG. 6  is a plan view in cross section of an upper rear portion showing flows of cooling air; 
           [0014]      FIG. 7  is a plan view in cross section of a lower rear portion showing flows of cooling air; 
           [0015]      FIG. 8  is a plan view in cross section of a lower rear portion of a modified construction having a rear cover placed on a support deck, showing flows of cooling air; 
           [0016]      FIG. 9  is a side view in vertical section of a principal portion of the modified construction having the rear cover placed on the support deck, showing flows of cooling air; 
           [0017]      FIG. 10  is a side view in vertical section of a principal portion of a modified construction having guide pieces provided for an upper cover, showing flows of cooling air; 
           [0018]      FIG. 11  is a plan view in cross section of the principal portion of the modified construction having the guide pieces provided for the upper cover, showing flows of cooling air; and 
           [0019]      FIG. 12  is a side view of a principal portion of a modified construction having right and left lower edges of an upper cover inclined upward, showing flows of cooling air. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    An embodiment in which this invention is applied to a riding type mowing machine which is one example of working vehicles will be described hereinafter. 
         [0021]      FIG. 1  shows a side elevation of the riding type mowing machine. As shown in  FIG. 1 , the riding type mowing machine in this embodiment is constructed the mid-mount type having a mower  5  vertically movably attached through a link mechanism  4  to a vehicle body  1  between a pair of right and left front wheels  2  and a pair of right and left rear wheels  3 . 
         [0022]    The vehicle body  1  includes a front frame  6  formed of square pipe or the like and disposed in a front part thereof. The front frame  6  supports the link mechanism  4 , and has right and left front wheels  2  arranged at right and left ends of a front end thereof to be dirigible about vertical axes. The link mechanism  4  can raise and lower the mower  5  in parallel by operation of a single-acting hydraulic cylinder  7 . 
         [0023]    The front frame  6  has a boarding step  8  formed of sheet metal and covering substantially the whole of the front frame  6  from above. The boarding step  8  has a rubber mat (not shown) laid over the surface thereof, and has, arranged in a middle front region thereof, a brake pedal  9  biased back to a non-braking position, and a lock pedal  10  for engaging and holding the brake pedal  9  in a braking position against the biasing force. A positionally adjustable driver&#39;s seat  11  is disposed rearwardly and upwardly of the boarding step  8 . Fenders  12  and shift levers  13  are arranged at right and left sides of the driver&#39;s seat  11 , respectively. An arch-like protection frame  14  is erected at the back of the driver&#39;s seat  11 . Thus, this riding type mowing machine has a driving platform  15  formed on a front portion of the vehicle body  1 . 
         [0024]    As shown in  FIGS. 1 through 7 , the vehicle body  1  includes a rear frame  16  connected to the rear end of the front frame  6 . The rear frame  16  has a pair of right and left side members  17  formed of sheet metal, and support deck  18  supported by rearward parts of the right and left side members  17 . The support deck  18  is bent to be substantially L-shaped in side view to have a bottom wall  18 A and a front wall  18 B, An air-cooled gasoline engine  19  is mounted on the bottom wall  18 A to have an output shaft  19 A thereof projecting forward of the vehicle body. 
         [0025]    A transmission device (an example of change speed devices)  20  is disposed forwardly and downwardly of the engine  19  for slowing down power from the engine  19  and dividing the power into propelling power and working power. The transmission device  20  houses a clutch (not shown) for connecting and disconnecting the working power. Hydrostatic stepless transmissions (which are one example of change speed device, hereinafter abbreviated as HSTs)  21  are arranged at right and left sides of the transmission device  20  for receiving the propelling power from the transmission device  20 . A reduction gear  22  is connected to an outer side of each HST  21  for receiving the power after a change speed by the corresponding HST  21 . Each reduction gear  22  has a corresponding one of the rear wheels  3  drivably attached thereto. Each HST  21  has a shift rod (not shown) interlocked to a corresponding one of the shift levers  13  to be shiftable in response to forward and rearward rocking of the corresponding shift lever  13 . 
         [0026]    With this construction, the right and left shift levers  13  are rockable forward and rearward to shift the HST  21  corresponding to each control lever  13 . In this way, the right and left rear wheels  3  can be driven at variable speed independently of each other. 
         [0027]    That is, this riding type mowing machine has the right and left front wheels  2  dirigible in a follow-up mode, and the right and left rear wheels  3  drivable at variable speed independently of each other. Consequently, the mowing machine can produce, as desired, a stopping state with the right and left rear wheels  3  stopped, a straight moving state with the right and left rear wheels  3  driven at equal speed forward or backward, a large radius turn state with the right and left rear wheels  3  driven at different speeds forward or backward, a pivot turn state with one of the right and left rear wheels  3  stopped and the other driven forward or backward, and a spin turn state with one of the right and left rear wheels  3  driven forward and the other backward, 
         [0028]    The transmission device  20  has a PTO shaft  20 A mounted in a lower front position thereof for taking the working power out for the mower  5 . The PTO shaft  20 A transmits the working power from the transmission device  20  to the mower  5  through a telescopic transmission shaft  23  and universal joints  24  attached to opposite ends of the transmission shaft  23 . That is, the mower  5  receives constant-speed power irrespective of traveling speed and running state. 
         [0029]    The rear frame  16  includes a rear cover  25  disposed at the rear end thereof and having right and left side walls  25 A and a rear wall  25 B. A plurality of exhaust holes  25   a  are formed in the rear wall  25 B of the rear cover  25 . An upper cover  26  covering an upper portion of the engine  19  from above is connected to the rear cover  25  to be pivotable open and close about an upper end of rear cover  25 . The upper cover  26  has a plurality of exhaust holes  26   a  formed in a rear wall  26 A thereof. A partition wall  28  is erected on the front wall  18 B of the support deck  18  for forming an engine room  27  with the rear frame  16 , rear cover  25  and upper cover  26 . In the engine room  27 , an air cleaner  29  is disposed above the engine  19 . A muffler  30  is disposed rearwardly of the engine  19 . 
         [0030]    Maintenance of the air cleaner  29  such as changing of elements can be carried out easily by opening the upper cover  26  (see  FIG. 3 ). The air cleaner  29  employed is the large-sized cyclone type which is made possible by using a large space formed above the engine  19  inside the engine room  27 . 
         [0031]    Though not shown, the rear frame  16  includes a holding mechanism holding the rear cover  25  in a closed position. 
         [0032]    As shown in  FIGS. 2 through 4 , the engine  19  includes a pair of right and left legs  19 B for forming a ventilating space S 1  between its bottom and the support deck  18 . The engine  19  further includes, disposed in front thereof, an engine cooling fan  19 C rotatable with the output shaft  19 A of engine  19 , and an air guide housing  19 D covering the cooling fan  19 C from front. The cooling fan  19 C in rotation draws ambient air into the air guide housing  19 D through a circular air intake  18   a  formed in the front wall  18 B of the support deck  18  and a circular air intake  19   a  formed in the front of the air guide housing  19 D, and causes the ambient drawn in to flow toward the engine  19  as cooling air. The air guide housing  19 D guides the cooling air from the cooling fan  19 C to areas around the engine  19  to cool the engine  19 . Part of the cooling air having passed through the areas around the engine  19  is led to areas around the muffler  30 , to cool the muffler  30 , by an air guide cover  31  attached to an upper rear end of the engine  19  for covering the muffler  30  from above. The cooling air having cooled the engine  19 , muffler  30  and so on is discharged outside through the exhaust holes  25   a  of the rear cover  25  and the exhaust holes  26   a  of the upper cover  26 . In this way, despite being the air-cooled type, the engine  19 , muffler  30  and so on can be cooled efficiently. 
         [0033]    A sleeve shaft  19 E is connected to the front end of the cooling fan  19 C to be rotatable with the cooling fan  19 C about the output shaft  19 A. The sleeve shaft  19 E supports a circular, porous dust-proof plate  19 F for preventing inflow of dust from the air intake  19   a  of the air guide housing  19 D to the interior of the housing  19 D caused by the sucking action of the cooling fan  19 C. 
         [0034]    As shown in  FIGS. 2 through 5 , a dust-proof plate  32  is attached to the bottom of the rear frame  16  and between the right and left side members  17  for covering, from below, a space S 2  formed between the transmission device  20  and right and left HSTs  21 , and the support deck  18 . The dust-proof plate  32  includes a bottom wall  32 A extending between the right and left side members  17 , a front wall  32 B extending from the forward end of the bottom wall  32 A upward toward the transmission device  20  and right and left HSTs  21 , and a rear wall  32 C extending from the rear end of the bottom wall  32 A upward toward the support deck  18 . The front wall  32 B has a recess  32   a  formed therein for receiving the transmission device  20 . 
         [0035]    This construction can prevent ambient air containing a large quantity of grass clippings and the like from being drawn from under the vehicle body toward the air intake  19   a  of the air guide housing  19 D as cooling air by the sucking action of the cooling fan  19 C. Instead, ambient air containing a less quantity of grass clippings and the like can be supplied as cooling air from above the vehicle body through between the driver&#39;s seat  11  and partition wall  28  toward the air intake  19   a  of the air guide housing  19 D. 
         [0036]    As a result, the quantity of dust such as grass clippings adhering to or depositing on and around the engine  19  can be reduced drastically, to reduce the time and trouble taken in cleaning. 
         [0037]    As shown in  FIGS. 1 through 6 , a dust removing cover  34  having a dust removing net  34 A is formed integral with the front end of the upper cover  26 . When the upper cover  26  is in the closed position, the dust removing cover  34  forms an ambient air introducing space  33  with the partition wall  28 , and removes dust from the ambient air flowing from above the vehicle body through between the driver&#39;s seat  11  and partition wall  28 . Thus, cleaner ambient air passing through the ambient air introducing space  33  can be supplied as cooling air from between the driver&#39;s seat  11  and partition wall  28  toward the air intake  19   a  of the air guide housing  19 D. 
         [0038]    Though not shown, the dust removing cover  34  may be formed separately from the upper cover  26 , and detachably erected on the rear frame  16 . 
         [0039]    As shown in  FIGS. 2 through 4 , an opening  32   b  is formed in the bottom wall  32 A of dust-proof plate  32 , and a lid  32 D is provided for opening and closing the opening  32   b . The lid  32 D is preferably plate shaped. The lid  32 D is vertically pivotable between open and closed positions about a pivot shaft  32 E extending right and left at the forward end of the bottom wall  32 A. The lid  32 D is biased upward toward the closed position by a torsion spring  32 F mounted on the pivot shaft  32 E. The lid  32 D has a control rod  32 G extending from a left front position of the lid  32 D upward toward the ambient air introducing space  33  for enabling the lid  32 D to be opened against the biasing force of the torsion spring  32 F. The control rod  32 G has an engaging piece  32 H welded to an upper position thereof for engaging, from below, an engageable element  35  provided in a rear upper left position of the transmission device  20 , to hold the lid  32 D in the open position with the biasing force of the torsion spring  32 F. 
         [0040]    With this construction, dust having deposited on an inner surface of the lid  32 D can be removed easily through the opening  32   b  of the bottom wall  32 A, by opening the upper cover  26  to move the dust removing cover  34  away from the rear frame  16 , and operating the control rod  32 G to open the lid  32 D. Dust having deposited on an inner surface of the dust-proof plate  32  can be removed easily through the opening  32   b  of the bottom wall  32 A by holding the lid  32 D in the open position. 
         [0041]    As shown in  FIGS. 2 through 5 , power is transmitted from the engine  19  to the transmission device  20  through a transmission shaft  36  relatively slidably splined to the sleeve shaft  19 E and a pair of front and rear universal joints  37 . The front universal joint  37  has a cooling fan  38  rotatable therewith. The cooling fan  38  in rotation draws ambient air from areas forward of the transmission device  20  and right and left HSTs  21 , and causes the ambient air to flow as cooling air around the transmission device  20  and right and left HSTs  21  to cool the transmission device  20  and right and left HSTs  21 . 
         [0042]    The transmission device  20  has, mounted on a lower rear portion thereof a hydraulic pump  39  for sucking and feeding under pressure oil (or fluid) stored inside the transmission device  20 , and a first oil filter  40  of the cartridge type for filtering the oil sucked by the hydraulic pump  39 . The oil fed under pressure by the hydraulic pump  39  can be supplied to the hydraulic cylinder  7  for vertically moving the mower, right and left HSTs  21  and clutch by operation of a control valve (not shown) and the like. Oil drained from the hydraulic cylinder  7  for vertically moving the mower, right and left HSTs  21  and clutch is returned to the interior of the transmission device  20 . A second oil filter  41  of the cartridge type is mounted on an upper front portion of the transmission device  20  for filtering the oil supplied to the right and left HSTs  21 . 
         [0043]    Maintenance of the first oil filter  40  such as changing of elements can be carried out easily through the opening  32   b  of the bottom wall  32 A by operating the control rod  32 G to hold the lid  32 D in the open position (see  FIG. 3 ). 
         [0044]    Between the partition wall  28  and cooling fan  38  for the change speed devices, an oil cooler  42  is disposed for cooling fluid supplied in circulation to the transmission device  20 , hydraulic cylinder  7 , right and left HSTs  21  and clutch. The oil cooler  42  is formed to extend to the ambient air introducing space  33  from between the engine cooling fan  19 C and cooling fans  38  for the change speed devices, and have lower portions straddling the universal joint  37  so that considerable portions thereof overlap the cooling fan  38  for the change speed devices when seen in the fore and aft direction. 
         [0045]    Thus, upper portions of the oil cooler  42  are supplied with engine cooling air flowing through the ambient air introducing space  33  into the air intake  19   a  of the air guide housing  19 D by the sucking action of the cooling fan  19 C opposed to the oil cooler  42 . Lower portions of the oil cooler  42  can be supplied with cooling air for the change speed devices having flowed around the transmission device  20  and right and left HSTs  21  by the sucking action of the cooling fan  38  for the change speed devices. 
         [0046]    The partition wall  28  includes a pair of right and left first air guiding plates  28 A arranged adjacent right and left ends of the oil cooler  42 , a pair of right and left second air guiding plates  28 B sloping inward and downward from lower edges of the respective first air guiding plates  28 A toward the air intake  18   a  of the support deck  18 , and a third air guiding plate  28 C extending between the right and left first air guiding plates  28 A and sloping rearward and downward from above the oil cooler  42  toward the air intake  18   a  of the support deck  18 . 
         [0047]    Thus, the right and left first air guiding plate  28  can prevent the heat of the engine room  27  from being drawn in through the air intake  19   a  of the air guide housing  19 D by the sucking action of the engine cooling fan  19 C. The right and left second air guiding plates  28 B and third air guiding plate  28 C can form an cooling air guide passage  43  extending from between the driver&#39;s seat  11  and partition wall  28  to the air intake  19   a  of the air guide housing  19 D, such that the passage  43  is tapered to become narrower from a region adjacent the cooling fan  38  for the change speed devices which is upstream in the flowing direction of cooling air, to a region adjacent the engine cooling fan  19 C which is downstream in the flowing direction of cooling air. This increases the speed of the cooling air passing through the air passage  43  of the cooling air, to increase the flow rate per unit time of the cooling air supplied to the engine  19  and oil cooler  42 . As a result, the engine  19 , and the oil cooler  42  located in the air passage  43 , can be cooled efficiently by the cooling air. 
         [0048]    The third air guiding plate  28 C is detachably attached to the partition wall  28  by engaging a pair of right and left engaging claws  28   b  formed by bending rear ends of the third air guiding plate  28 C, into a pair of right and left slits  28   a  formed in the partition wall  28 . By removing the third air guiding plate  28 C from the partition wall  28 , replenishment of grease for the sleeve shaft  19 E and universal joint  37  located under the third air guiding plate  28 C may be carried out easily through grease nipples  19   b  and  37   a  of the sleeve shaft  19 E and universal joint  37 . Dust adhering to the dust-proof plate  19 F, oil cooler  42  and so on may also be removed easily after removing the third air guiding plate  28 C from the partition wall  28  (see  FIG. 3 ). 
         [0049]    As shown in  FIG. 5 , the right and left first air guiding plates  28 A have buckle type connectors  28 D for engaging a pair of right and left engageable elements  28   c  formed on the forward end of the third air guiding plate  28 C to connect the forward end of the third air guiding plate  28 C to the right and left first air guiding plates  28 A. This arrangement can prevent generation of noise due to vibration of the third air guiding plate  28 C while the vehicle is traveling, for example. 
         [0050]    Though not shown, the third air guiding plate  28 C may be attached to the partition wall  28  to be pivotable between an operative position extending from the partition wall  28  to the upper end of the oil cooler  42 , and a retracted position standing along the partition wall  28 . The partition wall  28  may have an engaging device for engaging the third air guiding plate  28 C to retain the third air guiding plate  28 C in the retracted position. 
         [0051]    As shown in  FIGS. 2 ,  3 , and  7 , the bottom wall  18 A of the support deck  18  has a rear end bent downward. A space S 3  is formed between the rear end of the bottom wall  18 A and the rear cover  25 . The cooling air having passed through the space S 1  between the bottom of the engine  19  and the bottom wall  18 A of the support deck  18  is guided by the rear end of the bottom wall  18 A to flow promptly rearward and downward from the bottom wall  18 A, and is subsequently discharged outside the vehicle from spaces S 4  formed rearward and downward between the rear frame  16  and rear cover  25 . That is, the cooling air for the engine can be made to flow smoothly and promptly through the space S 1  between the bottom of engine  19  and the bottom wall  18 A of support deck  18 , to cool the bottom of engine  19  (lower surface of the crank case) efficiently. 
         [0052]    As shown in  FIGS. 8 and 9 , where the rear cover  25  has a forward end placed on a rear end portion of the bottom wall  18 A of support deck  18 , a recess  25   b  is formed in the forward end of the rear cover  25  for letting out the cooling air having passed through the space S 1  between the bottom of engine  19  and the bottom wall  18 A of support deck  18 . As a result, the cooling air having passed through the space S 1  between the bottom of engine  19  and the bottom wall  18 A of support deck  18  flows promptly toward the rear cover  25  through the recess  25   b  of the rear cover  25 , and is promptly discharged outside the vehicle from the exhaust holes  25   a  of the rear cover  25 . That is, the cooling air for the engine can be made to flow smoothly and promptly through the space S 1  between the bottom of engine  19  and the bottom wall  18 A of support deck  18 , to cool the bottom of engine  19  efficiently. 
         [0053]    As shown in  FIGS. 1 and 7 , the rear cover  25  is has right and left side walls  25 A inclined to converge with the right and left width progressively narrowing rearward. Thus, as the vehicle travels, ambient air present laterally outward of the engine  19  flows from a space S 5  ( FIG. 1 ) formed between each side member  17  of the rear frame  16  and the upper cover  26  toward the rear of engine  19  and the muffler  30  disposed rearwardly of the engine, to be discharged promptly through the exhaust holes  25   a  of the rear cover  25 . That is, by action of the rear cover  25 , ambient air present laterally outward of the engine  19  can be made to flow smoothly and promptly to the exhaust holes  25   a  of the rear cover  25 . These air flows can promote the speed of the engine cooling air flowing from the air intake  19   a  of the air guide housing  19 D toward circumferential areas of the engine  19 . As a result, the engine  19  and muffler  30  can be cooled with increased efficiency. 
         [0054]    As shown in  FIGS. 1 and 6 , the upper cover  26  is formed to diverge with the right and left width progressively broadening forward in plan view, to form rearwardly converging spaces S 6  between right and left lower edges  26 B thereof and the rear frame  16 . Thus, as the vehicle travels, ambient air present laterally outward of the engine  19  flows from the spaces S 6  between the right and left lower edges  26 B of the upper cover  26  and the rear frame  16  toward upper portions of the engine room  27 , to be discharged promptly through the exhaust holes  26   a  of the upper cover  26 . That is, by action of the upper cover  26 , ambient air present laterally outward of the engine  19  can be made to flow smoothly and promptly to the exhaust holes  26   a  of the upper cover  26 , to prevent the heat remaining in the upper portions of the engine room  27 . As a result, it is possible to avoid a situation where the heat stagnates in the upper portions of the engine room  27  housing the air cleaner  29 , and engine combustion efficiency lowers owing to a temperature increase of the air supplied to the engine  19 . 
         [0055]    As shown in  FIGS. 10 and 11 , a plurality of guide pieces  26   b  may be arranged along the right and left lower edges  26 B of the upper cover  26  for guiding the ambient air flowing in from the spaces S 6  between the right and left lower edges  26 B and the rear frame  16  to flow toward the rear wall  26 A of the upper cover  26 . Thus, ambient air present laterally outward of the engine  19  is made to flow smoothly and promptly toward the exhaust holes  26   a  of the upper cover  26 , thereby to avoid the above-noted lowering of engine combustion efficiency with increased assurance. 
         [0056]    As shown in  FIG. 12 , the upper cover  26  may have the right and left lower edges  26 B inclined upward and forward at predetermined angles θ1-θ3, to facilitate the ambient air present laterally outward of the engine  19  flowing toward the upper portions of the engine room  27 , thereby to avoid the above-noted lowering of engine combustion efficiency with increased assurance. 
         [0057]    As shown in  FIGS. 2 and 3 , a communicating tube  28 F is disposed above the third air guiding plate  28 C of partition wall  28  for communicating the engine room  27  and ambient air introducing space  33 . The air cleaner  29  has an air intake hose  44  connected to an inlet pipe  29 A thereof and inserted to the communicating tube  28 F. Thus, the engine  19  is supplied with fresh ambient air, through the air cleaner  29 , immediately after stripped of dust by the dust removing cover  34  above the vehicle body where little grass clippings are scattered, and not influenced by the engine  19  or oil cooler  42 . As a result, clogging of the air cleaner  29  can be inhibited effectively. Moreover, it is possible to avoid lowering of engine combustion efficiency due to supplying the engine with heated air, which would occur when air inside the engine room  27  or the ambient air having passed through the oil cooler  42  is supplied to the engine  19 . 
         [0058]    Though not shown, metal fittings for supporting the air cleaner  29  may be attached to an upper rear surface of the partition wall, so that the air cleaner  29  may be disposed on the upper rear surface of the partition wall  28 . 
       OTHER EMBODIMENTS 
       [0059]    [1]The working vehicles to which this invention is applicable include a mid-mount mower having a mower unit  5  disposed between right and left front wheels  2  and right and left rear wheels  3  of a four-wheel drive type vehicle body  1 , a front mower, a tractor, a riding type rice planting machine and so on. 
         [0060]    [2]The oil cooler  42  may be disposed opposite the cooling fan  38  for the change speed devices across the change speed devices  20  and  21 . 
         [0061]    [3]The oil cooler  42  may be disposed opposite the cooling fan  38  for the change speed devices without straddling the universal joint  37 .