Abstract:
A self-propelled agricultural vehicle is constructed by assembling the parts of a standard row-crop tractor to the point where the next step is that of mounting the cab to the chassis. At this point, a cab adapter module is mounted to the chassis using the mounting points normally used for mounting the cab to the chassis. The cab, provided in a form without the usual access ladder and fenders, is mounted to the cab adapter module so as to face in a direction opposite to that which it would face if mounted to the chassis. The seat and all controls for operating the tractor remain in the same locations in the cab regardless which direction the cab faces. Minor reconfigurations of hydraulic circuitry and the differential are required for permitting the vehicle to be operated in a forward direction opposite to that for the operation of the standard tractor.

Description:
FIELD OF THE INVENTION 
   The present invention relates to agricultural tractors, and more specifically relates to a way of manufacturing a self-propelled implement using the components of a standard row-crop tractor equipped with a cab. 
   BACKGROUND OF THE INVENTION 
   Traditionally, manufacturers of agricultural tractors make one type of tractor for row-crop work and another for serving as the power unit for self-propelled implements, such as a windrowers or mower-conditioners, for example. Standard agricultural tractors are often equipped with an operator&#39;s station housed within a cab which is situated between a pair of rear drive wheels of the tractor and facing forward toward an engine of the tractor, while the power unit for a self-propelled implement, such as a windrower, is commonly equipped with a cab located between a pair of front drive wheels and faces in a forward direction away from the engine so that the operator has excellent visibility of front-mounted equipment. The physical appearance of the tractor and power unit are generally similar, with the primary difference being the direction the vehicle is driven in normal forward operation. The manufacture of two different tractors leads to increased costs, especially if one or the other enjoys an economy of scale due to the number of units sold. 
   Heretofore, it has been known to provide a tractor equipped with a cab in which the seat, steering wheel and control console are mounted for swiveling about a vertical axis between a first position wherein the operator faces the engine and operates the tractor for towing implements, and a second position, wherein the operator faces away from the engine and operates the tractor in good view of front-mounted equipment. However, this known tractor has a hydrostatic transmission which may be easily reversed in operation without a degradation of function, i.e., the operating characteristics of the transmission remain the same for propelling the tractor in opposite directions. This is in contrast to a tractor equipped with a gear transmission wherein mating gears often have their greatest load carrying capacity only when driven so as to propel the tractor in one direction. An example of a prior art tractor which may be operated in a bi-directional manner is disclosed in U.S. Pat. No. 4,059,171. 
   Therefore, the problem to be solved is that of being able to use substantially all of the components of a standard, row-crop tractor in the manufacture of a dedicated, self-propelled implement tractor which has a forward operation mode that is the reverse of that of a standard row-crop tractor. 
   SUMMARY OF THE INVENTION 
   According to the present invention there is provided a way of utilizing substantially all of the components of a standard row-crop tractor, equipped with a cab, in constructing a self-propelled agricultural vehicle which has a normal forward direction of operation opposite to that of the standard row-crop tractor. 
   An object of the invention is to provide structure for use in conjunction with a cab-equipped, standard row-crop tractor for constructing a self-propelled vehicle having a normal forward direction of operation, that is the reverse of that of the standard tractor, without requiring movement of any of the controls contained within the cab. 
   The foregoing object is accomplished in part by providing a cab adapter module which may be optionally mounted to a first set of cab attachment points normally used for attaching the cab to the chassis of the standard tractor, with the cab adapter module being provided with a second set of cab attachment points to which the cab may be coupled so as to face in a direction opposite to that in which it would face if coupled to the chassis at the first set of cab attachment points. In the case where the tractor is equipped with a gear transmission, the differential ring gear is changed to mesh at the opposite side of the drive shaft pinion so as to reverse the output to the drive wheels. If desired, axle extensions may be used to increase the distance between the drive wheels. 
   These and other objects will become apparent from a reading of the ensuing description together with the appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is left front perspective view of a standard hi-crop tractor equipped with a cab. 
       FIG. 2  is a rear view of the tractor shown in  FIG. 1 . 
       FIG. 3  is a horizontal sectional view taken through the rear differential housing of the tractor shown in  FIGS. 1 and 2 . 
       FIG. 4  is a schematic view showing the hydraulic fluid circuitry used for the conveyance of fluid for steering and brake control with the standard tractor shown in  FIGS. 1 and 2 . 
       FIG. 5  is a left front perspective view of a self-propelled agricultural vehicle constructed utilizing most of the components of the standard tractor, illustrated in  FIGS. 1 and 2 , together with the cab adapter module of the present invention positioning the cab the and controls contained in the cab for a normal forward direction of operation opposite to that of the standard tractor. 
       FIG. 6  is a left rear perspective view of the self-propelled agricultural vehicle shown in  FIG. 5 . 
       FIG. 7  is a schematic left rear exploded view of the self-propelled vehicle shown in  FIGS. 5 and 6 , but in addition showing a windrower platform for attachment to the front hitch of the vehicle. 
       FIG. 8  is a view like  FIG. 3 , but showing the ring gear and associated components of the differential of the standard tractor repositioned for driving the self-propelled vehicle in its normal forward direction of operation. 
       FIG. 9  is a schematic view like that of  FIG. 4  but showing the hydraulic fluid circuitry used for the conveyance of fluid for steering and brake control with the self-propelled implement shown in  FIG. 3 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIGS. 1 and 2 , there is shown a standard agricultural row-crop tractor here depicted as a hi-crop tractor  10  having additional clearance beneath it for permitting the tractor to pass over growing crops without causing crop damage. The tractor  10  has a normal forward direction of travel indicated by the arrow FT. 
   The tractor  10  includes a fore-and-aft extending main frame  12  including a pair of transversely spaced, parallel frame members  14 . The frame  12  is supported for movement over the ground by a front pair of steerable ground wheels  16  and  16 ′ and by a rear pair of drive wheels  18  and  18 ′, with the wheels  16  and  18  being right-hand wheels, and with the wheels  16 ′ and  18 ′ being left-hand wheels as considered from the view point of a person standing behind the tractor  10  and facing in the direction of forward travel FT. The pair of front wheels  16  and  16 ′ are respectively mounted to out-turned spindles forming parts of generally L-shaped knuckle and spindle units  19  and  19 ′ having upright shaft sections respectively received within, and mounted for oscillating about respective upright axes defined by, tubular receptacles  20  forming opposite ends of a transverse front axle  22 . The front axle  22  is mounted, at its midpoint, to a forward end location of the main frame  12  for pivoting about a horizontal, longitudinal axis defined by a pair of longitudinally spaced, fore-and-aft extending, axially aligned horizontal pivot pins (not shown). The axle  22  includes opposite end sections which are disposed in overlapping relationship to a middle section and are containing adjustment holes which may be selectively aligned with holes provided in the center section for achieving an adjustment of the distance between the wheels  16  and  16 ′. 
   Bolted to the rear ends of the frame members  14 , and, thus, forming a rearward extension of the main frame  12 , is a rear differential gear housing  24  ( FIG. 3 ). Bolted to the rear side of the housing  24  is a rear PTO housing  26 . Respectively bolted to a right-hand surface of the housing  24  is a right-hand drop-axle or final drive housing  28 , and bolted to a left-hand surface of the housing  24  is a drop axle or final drive housing  28 ′. Each of the housings  28  and  28 ′ contains a shaft and gear arrangement (not shown) respectively coupled for driving the pair of rear drive wheels  18  and  18 ′. The rear differential gear housing  24  defines structure to which a three-point hitch  30  is mounted for carrying rear-mounted implements. 
   Power for driving the wheels  18  and  18 ′ and for supplying the power for operating various hydraulic and electrical components of the tractor is derived from an internal combustion engine  31  coupled to the main frame and located within a compartment defined by a hood and side panel arrangement  32  disposed over approximately a forward half of the main frame  12 . An operator&#39;s cab  34  includes a front window  36  positioned just behind the engine compartment  32  and a rear window  38  positioned approximately within a vertical transverse plane passing through the axis of rotation of the rear wheels  18  and  18 ′. The cab  34  is respectively mounted to the pair of frame members  14  by a pair of forward brackets  40  (only one shown), and to respective top locations of the pair of drop axle housings  28 , as at connections  42 . A main tractor transmission  43  extends between the engine  31  and the differential housing  24 . Thus, the cab  34  is positioned over the main tractor transmission  43  and the differential housing  24 , and is forward of the three-point hitch  30  so as to not interfere with its operation. 
   Located within, and mounted to the floor of, the cab  34  is a seat  44 , which places an operator within reach of a steering wheel  46  connected to a steering shaft  48  ( FIGS. 4 and 9 ) having a lower end received within a steering control valve  50  forming part of a steering control and mounted to a support panel (not shown) forming part of a control console  52 . In a manner discussed in more detail below, the steering control valve  54  is hydraulically coupled to a pair of steering cylinders  56  and  56 ′ ( FIGS. 3 and 4 ) respectively coupled between the front axle  22  and a pair of steering arms  58  and  58 ′, respectively coupled to the tops of the upright pins forming part of the L-shaped knuckle and spindle assemblies  19  and  19 ′. A tie-rod  60  is coupled between the steering arms  58  and  58 ′. 
   Mounted to a forward wall of the cab  34  at a location to the right of the steering shaft  48  is right- and left-hand brake pedals  62  and  64 , respectively, associated with separate brake valve elements (not shown) contained within a housing of a brake valve  66  mounted to the forward wall of the cab and operable, as discussed in more detail below, for controlling brakes  68  and  68 ′ ( FIGS. 4 and 9 ) respectively associated with the rear drive wheels  18  and  18 ′. 
   Also located so as to be within reach of a seated operator are a set of manually-operable levers  70  ( FIG. 2 ), which include at least one transmission shift control lever, although other control input devices such as knobs, etc. may be used. Although not an absolute necessity, the tractor transmission is preferably an electro-hydraulically controlled powershift transmission of a known design (for example, see U.S. Pat. No. 5,449,329, granted 12 Sep. 1995), which includes a plurality of fluid pressure operated clutches for controlling the flow of torque through the main transmission and a plurality of solenoid operated valves for selectively routing pressure fluid for effecting selected engagement of the clutches. In this patented transmission, the control system for actuating the solenoid valves and associated clutches includes micro-processor based electronic control units including a so-called chassis computer and a transmission control unit, the former receiving various pertinent input signals representing, for example, ground speed, engine speed, transmission oil temperature and the like, and sending these signals to the latter. Manual control is achieved by using a gear shift lever having switches associated therewith and an encoder that provides signals representing the position of the lever to the transmission control unit. Another manual control is similarly provided by operation of a clutch pedal. Thus, the only connection required between transmission control unit and the transmission is the wiring harness which couples the signal carrying lines to the transmission solenoid valves. 
   Referring now to  FIG. 3 , there is shown the housing  24  of the rear differential including a forward wall provided with a bore  74  in which a pinion shaft  76 , which extends from the main transmission  43 , is mounted for rotation through the agency of a bearing  78 . The pinion shaft  76  is integral with a pinion gear  80  that is meshed with a ring gear  82  mounted to one end of a differential housing  84  located within the housing  24  and having a right-hand end defining a cylindrical, tubular hub  86  mounted for rotation within an inner end of the right-hand final drive housing  28  through the agency of a bearing  88 , and having a left-hand end defining a cylindrical, tubular hub  90  mounted for rotation within an inner end of the left-hand final drive housing  28 ′ through the agency of a bearing  92 . Located within the differential housing  84  is a set of bevel pinions  94  (only one shown) which are meshed with a right-hand bevel gear  96  carried by a right-hand drive shaft  98  for driving the right-hand rear wheel  18 , and meshed with a left-hand bevel gear  100  carried by a left-hand drive shaft  102  for transmitting torque for driving the left-hand rear wheel  18 ′. A cavity  104  for containing a differential brake assembly (not shown) is defined at the right-hand end of the differential housing  84 . 
   Referring now to  FIG. 4 , there is shown a hydraulic control circuit  106  for controlling the steering and brake functions of the standard tractor  10 . Specifically, each of the steering valve  50  and brake valve  66  are coupled to a source of hydraulic pressure, here indicated as being a pump  108 , and a sump  110  by pressure and return lines  112  and  114 , respectively. A pair of hydraulic fluid conduits  116  and  118  are respectively coupled to separate work ports of the steering valve  50 . The conduit  116  is coupled, as by a quick coupler  120 , to a branched fluid conduit  122  coupled to the rod end of the steering cylinder  56  and to the head end of the steering cylinder  56 ′. Similarly, the conduit  118  is coupled, as by a quick coupler  124 , to a branched fluid conduit  126  coupled to the head end of the steering cylinder  56 ′ and to the rod end of the steering cylinder  56 . Thus, it will be appreciated that by turning the steering wheel  46  to the right (clockwise as viewed in  FIG. 4 ) the steering valve  50  will be actuated to connect the pump  108  to the rod end of the cylinder  56  and the head end of the cylinder  56 ′ so as to cause the knuckle and spindle units  19  and  19 ′ to be swiveled clockwise so as to turn the wheels  16  and  16 ′ to the right. Similarly, turning the steering wheel  46  counterclockwise will result in the cylinders  56  and  56 ′ being respectively extended and retracted so as to turn the wheels  16  and  16 ′ to the left. 
   The brake valve  66  includes a pair of work ports respectively to which are coupled fluid conduits  128  and  130 . The conduit  128  is coupled, as by a quick coupler  132 , to a conduit  134  coupled to the brake  68 , and the conduit  130  is coupled, as by a quick coupler  136 , to a conduit  138  coupled to the brake  68 ′. Thus, it will be appreciated that when the right-hand pedal  62  is depressed the brake valve  66  will be actuated to cause the brake  68  to be applied for braking the wheel  18 . Similarly, depressing the left-hand pedal  64  will cause the brake valve  66  to be actuated to cause the brake  68 ′ to be applied for braking the wheel  18 ′. 
   Referring now to  FIGS. 5–7 , there is shown a self-propelled vehicle  140  constructed using a majority of the components of the standard tractor  10 , with the common components being indicated by the same reference numeral call-outs as are used in describing the tractor  10 . The vehicle  140  has a normal forward direction of operation indicated by the arrow FV which is opposite to the normal forward direction of operation FT of the tractor  10 . 
   One major difference between the vehicle  140  and the tractor  10  is that the vehicle  140  includes a cab adapter module  142  which is mounted to the frame members  14  and axle housings  28  and  28 ′ using the front and rear pairs of mounting brackets  40  and  42  used for mounting the cab  34  (absent fenders and ladder) to the frame  12  and axle housings  28  and  28 ′. The cab  34  is bolted (not shown) directly to the top of the adapter  142  so as to be reversed in direction from its position shown in  FIGS. 1 and 2  and so as to be displaced rearward, as considered in  FIGS. 1 and 2 , of the location it occupies when mounted to the tractor  10 . The adapter  142  has an upper surface  144  which is elevated above the area occupied by a floor of the cab  34 , as mounted on the tractor  10 , so that the cab will not interfere with the operation of the three-point hitch  30 , which is here used to couple front mounted implements, such as a mower conditioner  150  (see  FIG. 7 ) to the vehicle  140 . In order to provide adequate clearance for a windrow forming structure  152  at the rear of the mower-conditioner  150  to fit between the wheels  18  and  18 ′, tubular axle extensions  154  and  154 ′ are respectively mounted between the housing  24  of the rear differential and the drop axle housings  28 ′ and  28 . The front axle  22  is in a lengthened condition relative to that shown in  FIGS. 1 and 2  so that the distance between rear wheels  156  and  156 ′ is commensurate with the spacing between the front wheels  18  and  18 ′. It is noted that the mower conditioner  150  includes a hitch attaching structure  158  located just forward of the windrow forming structure  152  and having respective connection points for the lower and upper draft links of the three-point hitch  30 . 
   The cab adapter module  142  further includes a ladder  160  which affords access to the cab  34  by way of the top surface of the adapter  142 . An appropriate guard rail  162  is also provided in the vicinity of an access door of the cab  34 . 
   So as to have the tread on the wheels  18  and  18 ′ properly oriented for the normal forward direction of travel FV of the vehicle  140 , the wheels  18  and  18 ′ are respectively mounted on the right- and left-hand sides of the vehicle  140 . It is also noted that the rear wheels  156  and  156 ′ are of a smaller diameter, this replacement is elective, not necessary. 
   Because the self-propelled vehicle  140  has a direction of operation that is opposite to that of the standard tractor  10 , it is desired that the output of the main transmission be reversed without changing the operation of the main transmission so that load transmitting capabilities of the gearing for forward operation is retained. This is accomplished according to the invention by reversing power flow through the rear differential. With reference to  FIG. 8 , it can be seen that the differential housing  84 , together with the bearings  88  and  92 , has, in effect, been rotated through 180°, relative to its position shown in  FIG. 3  so that the bearings  88  and  92  now respectively support the housing  84  for rotation within inner ends of the axle extensions  154 ′ and  154 . The ring gear  82  is now meshed with the left-hand side of the pinion  80  so that the differential housing  84  is rotated in a direction opposite to that in which it rotates in the arrangement of  FIG. 3 . A further change which is required when using the axle extensions  154  and  154 ′ is that the output shafts  98  and  102  are respectively replaced by longer output shafts  160  and  162 . 
   Because the cab  34  of the self-propelled vehicle  140  faces in a direction opposite to that in which it faces when used with the standard tractor  10 , a change is required in the circuitry illustrated in  FIG. 4  in order that the appropriate wheels will be steered and braked when the operator turns the steering wheel  46  and depresses the brake pedals  62  and  64 . With reference to  FIG. 9 , it can be seen that the conduit  116  is now connected to the branched conduit  126  by a length of conduit  164  forming respective quick coupler connections  166  and  168  with the conduits  116  and  126 . Similarly, the conduit  118  is now connected to the branched conduit  122  by a length of conduit  170  forming respective quick coupler connections  172  and  174  with the conduit  118  and branched conduit  122 . It will be appreciated then that turning the steering wheel  46  to the right (clockwise as viewed in  FIG. 9 ) will result in the right- and left-hand rear wheels  152  and  152 ′ turning to the left so that the rear part of the vehicle  140  tracks to the left and in this way causes the vehicle  140  to turn to the right. A left turn is similarly caused by turning the steering wheel to the left or counterclockwise. The additional lengths of conduit  164  and  170  are required to make up for the increased distance between the steering valve  50  and the connection points of the branched conduits  122  and  126  when the cab  34  is positioned for operation with the vehicle  140  as compared to when it is positioned for operation with the tractor  10 . 
   So that the right- and left-hand wheel  18 ′ and  18 , respectively, of the vehicle  140  are respectively braked when the right- and left-hand brake pedals  62  and  64  are depressed, the conduit  128  is coupled to the brake  68 ′ and the conduit  130  is coupled to the brake  68 . Because the distance of the brakes  68  and  68 ′ from the brake valve  66  is substantially the same for both the tractor  10  and the vehicle  140 , no additional length of conduit is required for coupling the brake valve  66  so as to correctly operate the brakes  68 ′ and  68  of the vehicle  140 . 
   It will be appreciated then that the present invention will have its highest utility if it is implemented during the manufacturing process. For example, if it is desired to change a manufacturing assembly line from one that is making standard tractors  10  to one for assembling self-propelled vehicles  140 , this may be done by merely by:
         1. changing the configuration of the preassembled rear differential so that it is in the configuration disclosed in  FIG. 9  (aside from the axle extensions  154  and  154 ′ and longer output shafts;   2. providing front axles  22  that are adjusted to the length desired for the vehicles  140 ;   3. providing any additional rear axle housing and shafting components as may be required to construct a rear axle having the desired length;   4. providing wheels of the desired size and tread orientation;   5. providing cab adapter modules  142 ;   6. providing cabs  34  which are preassembled without fenders or ladders attached; and   7. providing any additional conduits required for connecting the steering valve for proper steering operation of the wheels  152  and  152 ′.
 
Except for additional steps required in assembling the rear axle extensions  154  and  154 ′, for mounting the cab to the cab adapter  142  (the step for mounting the adapter takes the place of the step for mounting the cab  34  to the chassis), the assembly steps followed in constructing the self-propelled vehicle  140  are the same as those used in assembling the standard tractor  10 . Importantly, the cab adapter  142  and conduit extensions  164  and  170  are the only extra components used in constructing the vehicle  140 , with the different wheels, axle extensions and axle shafts also being available for use with standard tractors.
       

   Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.