Abstract:
An operating system for a tractor to which an implement is attachable, the operating system comprises: a steering wheel provided rearwardly of a hood that houses an engine located in a forward region of the tractor; a control panel provided rearwardly of the hood and adjacent the steering wheel; a center cover extending generally vertically below the steering wheel; an operation lever provided at a position laterally of the control panel; a valve unit with a pair of spools, the valve unit being located at a lower position with respect to the steering wheel and being covered by the center cover; a link mechanism that links the operation lever and the pair of spools, the link mechanism being covered by the center cover.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of co-pending patent application Ser. No. 11/375,373 filed Mar. 14, 2006, which claims priority to Japanese Patent Application Nos. 2005-131527 and 2005-191604 filed Apr. 28, 2005 and Jun. 30, 2005, respectively, all of which are hereby incorporated by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to operating systems for the front loader of a tractor. 
         [0003]    An implement is often connected to a tractor. When a front loader is connected to a front portion of a tractor as one such accessory implement, then, as shown in JP H4-110406U, for example, the left and right support beams of the front loader are connected via brackets to mounting seats that are provided to the left and right below the front portion of the driving portion, and to one of the brackets are attached valves for raising and lowering the boom and for rotating the bucket and an operation lever for operating these. 
         [0004]    The job of the front loader is to raise and lower the boom and rotate the bucket while repeatedly moving back and forth in the longitudinal direction of the tractor, and thus it is desirable for the loader operation lever to be furnished at a high position next to the steering wheel, and to this end, frames are provided specifically to support the operation lever at a high position, resulting in a configuration in which the loader operation structure is large and has many structural components. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the invention to provide an operating system that has an operation lever for a front loader that can be operated with ease while operating the steering wheel. A further aim of the invention is to provide an operating system that can provide a more comfortable space for the operator because the essential components of the operating system are furnished in the center frame. 
         [0006]    An operating system in accordance with the present invention for a tractor to which an implement is attachable, the operating system comprises: a steering wheel provided rearwardly of a hood that houses an engine located in a forward region of the tractor; a control panel provided rearwardly of the hood and adjacent the steering wheel; a center cover extending generally vertically below the steering wheel; an operation lever provided at a position laterally of the control panel; a valve unit with a pair of spools, the valve unit being located at a lower position with respect to the steering wheel and being covered by the center cover; a link mechanism that links the operation lever and the pair of spools, the link mechanism being covered by the center cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]      FIG. 1  is an overall lateral view of the tractor; 
           [0008]      FIG. 2  is a lateral view of the engine portion; 
           [0009]      FIG. 3  is a lateral view of the engine hood in the open state; 
           [0010]      FIG. 4  is a plan view showing a portion of the engine hood; 
           [0011]      FIG. 5  is a perspective view showing a stay for reinforcing the hood; 
           [0012]      FIG. 6  is a front view of the frame structure; 
           [0013]      FIG. 7  is a rear view of the frame structure; 
           [0014]      FIG. 8  is an exploded lateral view of the frame structure; 
           [0015]      FIG. 9  is a front view showing the partition portion of the frame structure; 
           [0016]      FIG. 10  is a front view showing the support frame portion of the frame structure; 
           [0017]      FIG. 11  is a front view of the interlocking lock mechanism; 
           [0018]      FIG. 12  is a lateral surface view of the tractor front to which a front loader has been mounted; 
           [0019]      FIG. 13  is a lateral view of the steering portion; 
           [0020]      FIG. 14  is a front view of the steering portion; 
           [0021]      FIG. 15  is a rear view of the front loader operation portion; 
           [0022]      FIG. 16  is a rear view showing the lever lock state of the front loader operation portion; 
           [0023]      FIG. 17  is a plan view showing the lever lock state of the front loader operation portion; and 
           [0024]      FIG. 18  is an exploded perspective view of the lever base portion. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]      FIG. 1  shows a tractor having an engine portion structure according to the invention. This four-wheel drive tractor is driven by front wheels  1  and rear wheels  2 , on the front side of the tractor is provided an engine portion  5  made of an engine  3  that is covered by an engine hood  4 , a driver&#39;s seat  6  is disposed between the left and right rear wheels  2 , and behind the driver&#39;s seat  6  is provided a rollover protection frame  7  with a top horizontal bar and a pair of vertical support columns. 
         [0026]    The engine hood  4  is made of a stationary lower hood  4   a  and an upper hood  4   b  that can be slid open and closed vertically about a fulcrum p at a front-portion thereof, and the engine  3  and the various machine components that are associated with the engine  3  are accommodated in the engine compartment R that is formed by the engine hood  4  and disposed in front of a radiator  8 . 
         [0027]    A frame structure  10  serving as the rear wall of the engine portion  5  is provided vertically at the rear portion of the engine compartment R, and to the frame structure  10  are mounted a panel cover  11  and a center cover  12  below the panel cover  11 . 
         [0028]    An instrument panel  13  and various switches are installed in the panel cover  11 , and a ventilation opening  14  whose structure blocks out dust is formed in the center cover  12 . The outside air that has been introduced through the ventilation opening  14  is sucked in by a radiator fan  9  and guided to the radiator  8 , after which the air flows forward in the engine compartment R, discharging heat within the room to the outside through ventilation openings  15  in the front face and lateral fore portions of the engine hood  4 . 
         [0029]    The lower hood  4   a  making up the lower portion of the engine hood  4  is formed in the shape of a flat bracket that is open to the rear and is fixedly joined to a vehicle frame  16 , and the ventilation openings  15  are formed in a meshed pattern in the forward face and the lateral faces of the lower hood  4   a.    
         [0030]    The upper hood  4   b  is pivotably connected to an upper end portion of a fixed support frame  17 , which extends vertically from the vehicle frame  16 , in such a manner that it can swing about the fulcrum p, and a pair of left and right front lights  18  are attached to the front end portion of the upper hood  4   b.  A gas spring  20  is engaged between the lateral center region of a fulcrum fitting  19  that is attached to the inner surface of the fore end portion of the upper hood  4   b  and a stay  17   a  that extends from the lateral center region of the fixed support frame  17 , and as shown in  FIG. 3 , the extension bias properties of the gas spring  20  are set in accord with the weight of the upper hood  4   b  so that the extension bias of the gas spring  20  safely holds the upper hood  4   b  at a open position that allows maintenance tasks to be performed. 
         [0031]    The upper hood  4   b  is also designed so that it is held in a closed orientation by an interlocking lock mechanism  21  that is disposed on its free-end side. That is, as shown in  FIG. 3 , an interlocking pin  22  is fastened to a center region of the rear free end portion of the upper hood  4   b  via a support fitting  23 , and a hook-shaped lock fitting  24  that engages the interlocking pin  22  is pivotably attached to the upper end portion of the frame structure  10  in such a manner that it can horizontally rotate about a fulcrum a. The lock fitting  24  is rotatively biased in the engaging lock direction by a spring  25 , and as shown in  FIG. 11(I) , the interlocking pin  22  of the upper hood  4   b,  which is closed in resistance to the gas spring  20 , engages the lock fitting  24  and holds the upper hood  4   b  in the closed position. 
         [0032]    An operation lever  24   a  is joined to the lock fitting  24  and extends above the panel cover  11 , and as shown in FIG.  11 (II), horizontally swinging the operation lever  24   a  to rotate the lock fitting  24  in resistance to the spring  25  has the effect of slightly lifting the upper hood  4   b,  whose lock has been released, due to the bias applied by the gas spring  20 , and simply by putting one&#39;s fingers there and pivoting this open with a wide swinging action, the upper hood  4   b  can be held in the open position by the gas spring  20 . 
         [0033]    It should be noted that, as shown in  FIGS. 3 to 5 , a stay  26  that is long in its lengthwise direction and that spans between the fulcrum fitting  19 , to which the gas spring  20  is connected, and the support fitting  23  of the interlocking pin  22 , is furnished in a vertical orientation along the inner surface of the roof of the upper hood  4   b,  and reinforces the upper hood  4   b , which is a resin mold. Thus, the upper hood  4   b  is kept from bending under the upward bias force applied by the gas spring  20  when its rear end is fixed in the interlocked state. 
         [0034]    As shown in  FIG. 8 , the frame structure  10 , which serves as the rear wall of the engine portion  5 , is made by joining a partitioning portion  10 A that is aluminum cast and horizontally wide and flat in the lengthwise direction, and a support frame portion  10 B that is aluminum cast as well and divided into left and right portions, and the portions  10 A and  10 B are joined by six threaded bolts  27  that position the two at appropriate locations in the lengthwise direction. 
         [0035]    As shown in  FIG. 6 , the partitioning portion  10 A of the frame structure  10  is formed at the same width as the lateral width of the rear end portion of the engine portion  5 , and the rear end of the engine hood  4  and the front end of the center cover  12  are disposed along the outer circumference of the partitioning portion  10 A. The air intake portion of the radiator  8  is furnished in a large opening  28  that is formed in a central portion of the partitioning portion  10 A, and the outside air that is taken in through the ventilation opening  14  of the center cover  12  is guided to the radiator  8  by way of the frame structure  10 . A step support portion  10   c  is provided projecting horizontally outward from the left and right lower end portions of the partitioning portion  10 A, and the left and right front of a step  29  that is disposed in the feet area of the driver&#39;s seat  6  rests on and is fastened to the step support portion  10   c.  A recessed portion  30  that is bent downward in the shape of a hook is formed in the left and right outer circumference portions of the partitioning portion  10 A, and wiring and hydraulic hoses H are inserted into the recessed portion  30  from the side and are safely held on the bottom side of the recessed portion  30 . 
         [0036]    As shown in  FIG. 10 , the left and right support frame portions  10 B of the frame structure  10  are joined by bolts, and at their lower end portions are furnished with a pair of left and right leg portions  10   d.  The leg portions  10   d  extend wide to the rear and rest on and are bolted to the vehicle frame  16 , and this allows the entire frame structure  10  to be safely fastened upright. 
         [0037]    A box-shaped portion  10   e  that is open in the lengthwise direction is provided in the upper half of the support frame portion  10 B, and forms a battery support portion B. The battery support portion B is formed projecting rearward, a predetermined distance upward away from the leg portions  10   d,  such that a battery  31  can be inserted into the inner space of the battery support portion B, which is formed in the shape of a box, from the rear and fixedly attached. It should be noted that the rear end of the box-shaped portion  10   e  and the vehicle frame  16  are connected by a stay  32  and serve as reinforcement for the battery support portion B, which receives the weight of the battery. Openings  33  are formed in the left and right lateral faces of the box-shaped portion  10   e,  and these improve air circulation within the battery containment space and make the battery support portion B more lightweight. 
         [0038]    A mounting seat  10   f  extends rearward and upward on an upper portion of the battery support portion B, which is formed in a box shape, and by connecting this to a hydraulic controller  34  for power steering, the left and right partitions of the support frame member  10 B are joined at an upper portion as well. An operation shaft  35  to which a steering handle  36  is attached extends upward from the hydraulic controller  34 . The hydraulic controller  34  delivers an amount of pressurized oil that corresponds to the amount that the steering handle  36  has been rotatively actuated, in a direction that corresponds to the direction in which the handle has been actuated, supplying it to hydraulic cylinders  37  for front wheel steering via the hydraulic hoses H. 
         [0039]    The leg portions  10   d  also function as valve support portions V, and as shown in  FIG. 14 , this allows a support plate  38  to be attached to the upper surface of the left and the right leg portions  10   d , and a valve  39  (valve unit) can be attached onto the support plate  38 . 
         [0040]    The valve  39  is for driving hydraulic drive-type accessory implements, and  FIGS. 12 to 14  show a tractor, and the steering portion thereof, in which a front loader  40 , which is one example of an accessory implement, has been connected to the front of the vehicle. 
         [0041]    The front loader  40  is made of a pair of left and right support frames  42  that are fixedly joined in a detachable manner to support brackets  41 , which are provided at the left and the right of the front portion of the tractor machine  1 , a pair of left and right booms  43  that are connected to the upper end portion of the support frames  42  in such a manner that they can be swung vertically, and a bucket  44  that is connected to the left and right booms  43  over their front ends in such a manner that it can rotate vertically, and the booms  43  are lifted up and down by a lift cylinder  45  and the bucket  44  is rotatively driven by a tilt cylinder  46 . 
         [0042]    An operation lever  47  for operating the valve  39  is disposed on the upper right side of the frame structure  10 , and the connecting structure for linking the valve  39  and the operation lever  47  is described below. 
         [0043]    The valve  39  is furnished with two spools  48  and  49  that can slide laterally and that project to the right of the machine, where the one spool  48  can be slid between three positions to select extension, retraction, or an intermediate stationary state of the lift cylinder  45 , and the other spool  49  can be slid between three positions to select extension, retraction, or an intermediate stationary state of the tilt cylinder  46 . 
         [0044]    The operation lever  47  and the two spools  48  and  49  are operatively connected by a link mechanism  50 , and their structures are shown in detail in  FIGS. 14 and 15 . 
         [0045]    A support bracket  51  is bolted to an area on the right side of the upper portion of the frame structure  10 , and a lever spindle  53  is fitted into and supported by a lateral boss portion  52 , which is provided in the support bracket  51 , in such a manner that it can rotate about a lateral axis x. The operation lever  47  is linked to a rotating fitting  54  that is connected by pins to the outer end portion of the lever spindle  53  in such a manner that it can rotate to the left and right about a longitudinal axis y that is at a right angle to the lateral axis x, and thus the operation lever  47  is supported in such a manner that it can swing in a cross about the two perpendicular axes x and y. 
         [0046]    An operation arm  55  is integrally connected to the inner end portion of the lever spindle  53 , and the operation arm  55  and a bell crank  56  that is operatively connected to an end portion of the spool  48  for the lift cylinder are operatively connected via a push-pull rod  57  that is long in the vertical direction. The rotating fitting  54  connected to the operation lever  47  and a relay bell crank  58  that is pivotably linked to the support bracket  51  in such a manner that it can rotate about a fulcrum z in the longitudinal direction are operatively connected to one another by way of a rod  59 , and a bell crank  60  that is operatively connected to the spool  49  for the tilt cylinder and the relay bell crank  58  are operatively connected to a push-pull rod  61  that is long in the vertical direction. 
         [0047]    Operatively connecting the operation lever  47 , which can be actuated in a cross shape as above, and the two spools  48  and  49  via the link mechanism  50  allows the lift cylinder  45  to be actuated by swinging the operation lever  47  in the longitudinal direction and allows the tilt cylinder  46  to be actuated by swinging the operation lever  47  in the lateral direction. 
         [0048]    The relay bell crank  58 , the push-pull rods  57  and  61 , and the valve  39  are covered and hidden by the center cover  12 , and the outside air that is sucked in through the ventilation openings  14  of the center cover  12  and circulated toward the radiator  8  cools the valve  39  and the battery  32 . 
         [0049]    The support bracket  51  is provided with a lock lever  62 . The lock lever  62  is provided connected to a spindle  63  that is supported in such a manner that it can swing about a longitudinal axis d, and can be switched between and held in two separate states via a toggle spring  64 . That is, as shown in  FIG. 15 , when the lock lever  62  is swingingly toggled to an orientation in which it faces the machine interior, a lock lip  65  that projects from the spindle  63  is moved from below the rotating fitting  54  to an away position in the machine interior, thereby allowing rotation of the rotating fitting  54  about the x and y axes. As shown in  FIG. 16 , when the lock lever  62  is toggled to an orientation in which it faces away from the machine, the lock lip  65  becomes positioned directly below the rotating fitting  54  and the interlocking portion  54   a  that projects downward from the rotating fitting  54  engages a lock hole  66  that is formed in the lock lip  65 , and this prevents rotation of the rotating fitting  54  about the x and y axes and thereby keeps the operation lever  47  from being actuated inadvertently. 
       OTHER EMBODIMENTS 
       [0050]    (1) It is also possible to adopt a configuration in which the battery support portion B provided in the frame structure  10  is in the shape of a box that opens to the side, so that the battery  31  is inserted and removed from the side. 
         [0051]    (2) In the foregoing embodiment, the leg portions  10   d  for connecting to the vehicle frame  16  were formed in the support frame portion  10 B, but it is also possible to adopt a configuration in which the step support portion  10   c  and leg portions  10   d  functioning as valve support portions V are formed in a single unit with the partitioning portion  10 A. Further, it is also possible to form the entire frame structure  10  through aluminum-pressure die-casting.