Abstract:
A work vehicle includes a vehicle frame and a roll-over protective structure mounted to the frame. The roll-over protective structure includes a plurality of upright support posts supporting a roof. Each support post includes a lower post section and an upper post section detachably coupled together in an end-to-end arrangement.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a non-provisional application based upon U.S. provisional patent application Ser. No. 60/840,549, entitled “ROLL-OVER PROTECTIVE STRUCTURE FOR A WORK VEHICLE WITH REMOVABLE PORTION FOR AIR TRANSPORT”, filed Aug. 28, 2006. 

   FIELD OF THE INVENTION 
   The present invention relates to work vehicles, and, more particularly, to roll-over protective structures for such work vehicles. 
   BACKGROUND OF THE INVENTION 
   A work vehicle such as a motor grader, bulldozer or the like typically includes a roll-over protective structure (ROPS) to comply with governmental safety regulations. In the case of a work vehicle having an enclosed operator cab, the ROPS is typically incorporated into the framework of the cab. More particularly, the cab typically includes corner posts supporting an overhead roof, and safety glass spanning between the corner posts allowing visibility by an operator. The corner posts are single piece corner posts which are sized and configured to withstand roll-over requirements. The one piece nature of the corner posts results in the work machine having a fixed overall height. 
   Most new work vehicles such as agricultural tractors that do not include an operator cab have a ROPS in the form of an upside down U-shaped frame which extends above the height of the operator when seated. To allow the tractor to be used in buildings having lower doorways or along overhanging tree limbs, the ROPS may be folded rearwardly about mid height of the ROPS, thereby decreasing the effective height of the ROPS. Such an arrangement obviously cannot be used to fold over an operator cab. 
   For one application, it is desirable for a motor grader unit to be field-altered such that the overall height of the machine can be less than 102 inches tall. The machine must be able to be operated in this condition so that it can be driven onto a cargo plane for air transport. For example, when such a work machine is used in support of military operations, it may be desirable to load the work machine onto a C-130 air cargo transport plane for transport to a selected location. The rear loading ramp and door opening have a maximum height of 102 inches, resulting in the overall machine height requirement specified above. Parts of the machine can be disassembled and shipped on a skid separate from the rest of the machine for this operation. When the machine is fully re-assembled, it must meet ROPS safety requirements according to ISO 3471. 
   What is needed in the art is an operator cab having a ROPS which may be quickly and easily altered to decrease the overall height of the vehicle, particularly for use during transport of the work vehicle. 
   SUMMARY OF THE INVENTION 
   The present invention provides a ROPS structure for an operator cab in a work vehicle which can be split at a desired vertical height for transport, and reassembled in the field for subsequent use. 
   The present invention in one form is directed to a work vehicle including a vehicle frame and a roll-over protective structure mounted to the frame. The roll-over protective structure includes a plurality of upright support posts supporting a roof. Each support post includes a lower post section and an upper post section detachably coupled together in an end-to-end arrangement. 
   The present invention in another form is directed to a work vehicle including a vehicle frame and an operator cab carried by the frame. The operator cab includes a plurality of upright support posts supporting a roof. Each support post includes a lower post section and an upper post section detachably coupled together in an end-to-end arrangement. A plurality of windows respectively span between adjacent support posts. Each window includes an upper window section and a lower window section detachably coupled together. 
   The present invention in yet another form is directed to a roll-over protective structure for use with a work vehicle. The roll-over protective structure includes a plurality of upright support posts supporting a roof. Each support post includes a lower post section and an upper post section detachably coupled together in an end-to-end arrangement. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view illustrating an embodiment of a ROPS of the present invention including a removable top portion; 
       FIG. 2  is a front, perspective view of the ROPS shown in  FIG. 1 , with the glass removed; 
       FIG. 3  is a rear, perspective view of the ROPS shown in  FIGS. 1 and 2 , with the glass installed; 
       FIG. 4  is a front, perspective view of the ROPS shown in  FIGS. 1-3 , with the glass installed; 
       FIG. 5  is a perspective view of a vertical rear post at the rear corners of the cab, showing a pair of internal C-channel coupler plates which interconnect the top and bottom vertical rear posts; 
       FIG. 6  is another perspective view of the C-channel coupler plate shown in  FIG. 5 ; 
       FIG. 7  is a perspective view of a vertical front post at the front corners of the cab, absent the external coupler plate which interconnects the top and bottom vertical front posts; 
       FIG. 8  is a perspective view of a vertical mid post at the rear of the access door of the cab, absent the external coupler plate which interconnects the top and bottom vertical mid posts; and 
       FIG. 9  illustrates an embodiment of a window flange used in the ROPS of the present invention. 
   

   DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, and more particularly to  FIGS. 1-4 , there is shown an embodiment of a work machine  10  of the present invention. Work machine  10  is in the form of a motor grader in the embodiment shown in the drawings, but may also be configured as a different type of work machine, such as a bulldozer, backhoe, agricultural tractor, track hoe, etc. Work machine  10  generally includes a vehicle frame  12  carrying an operator cab  14 . Frame  12  also carries an internal combustion (IC) engine which is housed within an engine compartment  16 , with the IC engine in turn providing motive force to wheels  18 . 
   Operator cab  14  includes an integral ROPS  20  having a plurality of upright support posts  22  which support a roof  24 . ROPS  20  also optionally includes a plurality of windows  26  spanning between upright support posts  22 , and a pair of doors  28  which are pivotally and removably carried by a corresponding upright support post  22  on either side of ROPS  20 . 
   Upright support posts  22  include a pair of rear corner posts  30 , a pair of front corner posts  32  and a pair of door posts  34 . Rear corner posts  30  have a generally rectangular cross-section as shown in  FIG. 5 , and are the most substantial of the various upright support posts  22  of ROPS  20 . Front corner posts  32  and door corner posts  34  each have a generally W-shaped cross-section (as shown in  FIGS. 7 and 8 , respectively) also providing rollover strength to ROPS  20 , while at the same time providing a recessed flange  36  against which a corresponding door  28  is seated when installed. 
   Each of rear corner posts  30 , front corner posts  32  and door posts  34  have a lower post section and an upper post section which are detachably coupled together in an end-to-end arrangement. More particularly, each rear corner post  30  includes a lower post section  30 A and an upper post section  30 B; each front corner post  32  includes a lower post section  32 A and an upper post section  32 B; and each door post  34  includes a lower post section  34 A and an upper post section  34 B. 
   Rear corner posts  30  are coupled together using C-channel coupler plates  38  which are positioned within the rectangular opening defined within rear corner posts  30 . Each coupler plate  38  extends longitudinally within a corresponding lower post section  30 A and upper post section  30 B. In the embodiment shown in the drawings, coupler plates  38  are welded to upper post sections  30 B, and bolted to lower post sections  30 A (see  FIGS. 5 and 6 ). A hollow tube section  40  is welded to the inside of coupler plate  38 , and a threaded nut  42  is welded to the end of tube section  40 , allowing the use of a threaded bolt through lower post section  30 A. As shown in  FIGS. 5 and 6 , coupler plates  38 , including tube sections  40  and nut  42 , do not fill the entire cross-section of a corresponding corner post  30 , such that air may pass through rear corner posts  30  as part of the heating and air conditioning system within operator cab  14 . 
   Coupler plates  44  are used to detachably couple each of front corner posts  32  and door posts  34 . Each coupler plate  44  is generally an elongated metal strap with four holes for receiving corresponding threaded fasteners  46 , such as bolts. Each coupler plate  44  is positioned on an outside of a corresponding front corner post  32  or door corner post  34 , such that two bolt holes overlie a lower post section  32 A or  34 A, and the other two bolt holes overlie an upper post section  32 B or  34 B. 
   The Front C-shaped coupler plate  38  is shown cutoff at the split line between lower post section  30 A and upper post section  30 B in  FIG. 5  for the purpose of illustrating the method of mounting, but in fact is approximately twice the height shown in  FIG. 5  (the same as the coupler plate  38  shown at the rear in  FIG. 5 ). 
   Each window  26  is sized to span between adjacent upright support posts  22 , including rear corner posts  30 , front corner posts  32  and door posts  34 . Each window  26  includes an upper window section  48  and a lower window section  50  which are detachably coupled together to allow upper window sections  48  to be removed with corresponding upper post sections  30 B,  32 B and  34 B during disassembly for transport. Each upper window section  48  includes an upper mounting flange  52  positioned at the bottom edge thereof and extending between adjacent upright posts  22 . Similarly, each lower window section  50  has a lower mounting flange  54  positioned at the upper edge thereof and extending between adjacent upright support posts  22 . Upper mounting flange  52  and lower mounting flange  54  are detachably coupled together, such as by using fasteners  56  shown in  FIG. 9 . Upper mounting flange  52  includes an overhang  58  which provides the dual functionality of creating a water shed relative to lower window section  50  when the upper half of ROPS  20  is installed, and protecting the lower edge of upper window section  48  from physical damage when the upper half of ROPS  20  is removed for transport. An environmental seal  60  is positioned between each upper mounting flange  52  and lower mounting flange  54 , and may be of any suitable configuration. 
   Each door  28  is of single piece construction, and is removably attached to an adjacent front corner post  32  or door posts  34  using a detachable hinge  62 . Hinge  62  may include a hinge plate (see  FIG. 1 ) which is fastened to a corresponding front corner post  32  or door post  34 , or may include a removable hinge pin, etc. 
   Although operator cab  14  is shown with two doors  28  in the embodiment illustrated in the drawings, it is of course also possible to provide operator cab  14  with a single door  28 , depending upon the application. Moreover, for certain applications, it may be desirable for operator cab  14  not to include doors  28  or windows  26  (such as may be the case if work machine  10  is used in a hot environment and does not include air conditioning). 
   To disassemble the upper portion of operator cab  14 , doors  28  are removed and the bolts are removed from coupler plates  38  and  44 . As a unit, roof  24 , upper post sections  30 B,  32 B,  34 B and upper window sections  48  with attached upper mounting flanges  52  are lifted upwardly from operator cab  14  using a chain hoist, cable hoist, or the like. Removal of the upper portion of operator cab  14  does not affect any of the controls for operation of work machine  10 , and an operator may simply sit within the lower portion of operator cab  14  using all of the normal controls, levers, pedals, etc. Work machine  10  is then loaded onto a transport vehicle, such as a C-130 air cargo transport plane, with the upper portion of operator cab  14  removed. Concurrently, the upper portion of operator cab  14  may be placed on a skid and fastened down to prevent any damage during transit. At the end use location, work machine  10  is unloaded from the transport vehicle and the upper half of operator cab  14  is attached to the lower half of operator cab  14  in a reverse manner. When assembled together, rear corner posts  30 , front corner posts  32  and door posts  34  define the integral ROPS  20  of operator cab  14 . 
   It will be appreciated that the particular shape of the couple plates  38  and  44 , as well as the number of coupler plates used, may vary depending upon the application. Also, the couplers need not necessarily take the form of coupler plates, and may be other suitable types of couplers. Further, the particular configuration of the mating window flanges can vary. Moreover, the doors to the cab are not split but are removed for shipping. However, it is possible that the doors could also be split. 
   Additionally, the particular location of the split lines relative to upright support post  22  and windows  26  can vary depending upon the application. For example, depending upon the type of work machine and the desired total height of the work machine when ROPS  12  is in a disassembled state, the particular locations of the split lines can vary. 
   Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention.