Abstract:
An under-frame shield, particularly useful with crop sprayers and other implements which traverse fields of plants, includes one or more flexible sheet material shields connected to axle structure and to a central rigid shield by resilient connectors to facilitate suspension system movement in all directions without sacrificing ground clearance. The connection structure and sheet material shields maintain a smooth, seamless protective surface on the under side of the machine to reduce vehicle and crop damage.

Description:
FIELD OF THE INVENTION 
     The present invention relates to crop shields for agricultural vehicles and, more specifically, to a flexible under-frame shield for such vehicles. 
     BACKGROUND OF THE INVENTION 
     Agricultural vehicles such as self-propelled sprayers have undersides that must be shielded to protect the vehicle from wear and damage by the plants and to protect the plants contacting the vehicle, particularly when the vehicle moves through tall crops. Currently available under-frame shielding typically utilizes stationary sheet metal which cannot flex to allow axle movements in floating axle or pivoting axle suspension systems. With movement of the axle, the distance between the axle and fixed locations on the under-frame will vary so that stationary arrangements are ineffective. Various shielding configurations have been proposed, such as shown in commonly assigned U.S. Pat. Nos. 5,405,292; 5,850,727; and 7,025,168. Such shields are not entirely satisfactory for providing a continuous barrier between the plants and the vehicle that does not harm the crop while adequately protecting the vehicle when operating in either the forward or reverse direction. In addition, many previously available shielding arrangements fail to provide adequate access to the lower portion of the vehicle during inspection and maintenance. 
     More recently, a new floating axle suspension system which eliminates expensive chrome spindles is described in commonly assigned and copending U.S. patent application Ser. No. 12/045,107, filed 10 Mar. 2008, entitled SUSPENDED AXLE FOR SPRAYER. Pairs of bars extend generally in the fore-and-aft direction from each axle and support the axle for vertical movement relative to the frame. A shield is required that provides protection adjacent the axle support bars and still accommodates the axle and bar movement. 
     SUMMARY OF THE INVENTION 
     An under-frame shields utilizes a combination of solid and flexible material with attachment and fastening structure facilitating axle movement and the resulting changes in position between attachment locations. A tarp or rubber material or other flexible material under the steering or tie rod mechanism accommodates twisting of the axle and, in a system with axle supporting rods, provides protection under substantially all the axle and axle supports. One end of the flexible shield portion attaches directly to the axle and moves with the axle. The opposite end of the flexible material is supported by brackets depending from the frame. A resilient strap system connects the opposite end to a generally rigid shield portion. An ultra-high molecular weight material (UHMW) bearing surface is interposed between the end of the flexible material and the rigid shield portion. In one embodiment, the rigid shield portion includes an upwardly opening sheet metal channel extending under the central belly portion of the vehicle. The strap system and contact surface allow the shield to move fore-and-aft with relatively little friction and wear while maintaining a consistent tension on the flexible shield material for maximum under-frame clearance and protection. 
     The under-frame shield allows the suspension system to move in all directions without sacrificing ground clearance. Therefore, the shield can afford superior protection, even when used with floating axle structures. The shield portions define a generally smooth seamless surface without gaps or sharp edges on the underside of the machine to reduce crop damage to allow machine operation in both forward and reverse directions, even in more mature crops. The straps can be disconnected and the rigid shield released to lower the shield from a working position to an access position. Continuous and generally seamless axle to axle shielding may be provided by utilizing a combination of flexible and non-flexible shields. 
     These and other objects, features and advantages of the present invention will become apparent from the description below in view of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a vehicle having an under-frame shield. 
         FIG. 2  is a bottom view of the vehicle of  FIG. 1 . 
         FIG. 3  is a perspective view of the shield with the access area in the open or service position. 
         FIG. 4  is an enlarged view of the shield of  FIG. 3 . 
         FIG. 5  is an enlarged side view of the front portion of the vehicle of  FIG. 1  showing the front flexible portion of the shield protecting axle and axle support area. 
         FIG. 6  is enlarged view, partially in section, showing the anti-friction pad support and connector structure between shield portions. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  therein is shown an agricultural vehicle  10  adapted for movement over a field of tall plants. As shown, the vehicle  10  is self-propelled sprayer having a main frame  12  supported for forward movement over the ground by a forward wheel axle assembly  16  and an aft wheel axle assembly or structure  18  including transverse beams  16   b  and  18   b  supporting transversely spaced wheels  16   w  and  18   w , respectively. At least the forward axle assembly  16  is steerable and is movably connected to the main frame  12  by suspension structure  20 F ( FIG. 5 ) which allows the beam  16   b  to rock vertically as the wheels  16   w  move over ground surface irregularities. A cushioning member or air bag  16   c  is interposed between the frame  12  and each side of the beam  16   b , and shock absorbers  16   s  help dampen axle movement. As shown, the suspension structure  20 F is of the type shown and described in the aforementioned U.S. application Ser. No. 12/045,107 and includes pairs of connecting rods  20   c  which, when viewed from the top, define an X, and when viewed from the side as shown in  FIG. 5 , are parallel to each other. The forward ends of the rods  20   c  are pivotally connected at locations  20   p  to the aft face of the beam  16   b , and the aft ends of the rods  20   c  are pivotally connected to the main frame  12  generally above the rearmost extremity of the wheel  16   w.    
     The rear axle assembly  18  may be fixed or moveably mounted. As shown, the rear axle assembly  18  is substantially similar to the front axle assembly  16  and is supported for rocking relative to the main frame  12  by suspension structure  20 R similar to but generally the mirror image of the structure  20 F. Although specific suspension and wheel assembly structure is described, it is to be understood that other types of suspension structures may also be utilized with the present invention. 
     The main frame  12  supports an engine compartment  22  forwardly and above the axle assembly  16 , an operator access and cab area  24  above the axle assembly  16  and a tank or other treatment container  26  behind the cab area  24 . The operator access and cab area  24  includes a retractable ladder  24 L movable upwardly from an access position shown in  FIG. 1  to a storage position (not shown) alongside the frame  12  to avoid plant contact during field-working operations. 
     As the vehicle  10  travels over a field of crops to be treated, the plants tend to deflect under the frame  12 , and shielding is required to prevent both vehicle damage and plant damage. An under-frame plant shield assembly  30  includes a fore-and-aft extending flexible sheet shield material  32  having a transversely extending forward portion  32 F with opposite sides  32   a  and  32   b  connected by a bracket and shield assembly  34  to the forward axle assembly  16 . 
     As shown in  FIGS. 1 and 5 , the shield material  32  extends under the axle structure or beam  16   b  and under the fore-and-aft extending suspension structure  20 F. The material  32  flexes with movement front axle assembly  16  and suspension structure  20 F relative to the frame  12 . 
     Shield support structure  40  includes pairs of pivots  42  depending from the frame  12  and connected by releasable pivot pins  43  to a fore-and-aft extending and generally channel-shaped rigid central shield  44  with upturned sides  44   u . The structure  40  supports the shield  44  under the central portion of the frame  12  for pivotal movement between a raised working position ( FIGS. 1 and 2 ) and a lowered access position ( FIGS. 3 and 4 ). By removing a set of the pins  43  from a pair of pivots  42  on either side of the frame, the shield may be pivoted downwardly about a corresponding pivotal axis  42   a  or  42   b  for access to the underside of the vehicle  10 . The shield  44  may be completely removed from the vehicle  10  by removing all of the pivot pins  43  from both sides of the support structure  40 . 
     The support structure  40  as shown is rigid and includes brackets  46  depending from the frame  12  and having bifurcated ends  48  receiving bushings  49  attached to the sides of the shield  44  and supported therein by the pins  43 . The rigid shield  44  includes a forward end  44 F connected to the aft end  32 R of the shield material  32  at a first joint location  50 . Resilient or stretchable connector structure  52  extends between slot locations  56  in the central shield  44  and the flexible shield  32  at the first joint location  50 . The structure  52  allows the aft end  32 R to move fore-and-aft and flex side-to-side as necessary during axle and suspension movement and helps to maintain the shield material  32  taut to provide a smooth plant repellent surface and maximize under-frame clearance. The connector structure  52  may be released by removing the connector ends from the slot locations  56  in the shield  44  so the shield  44  may be pivoted downwardly about either axis  42   a  or  42   b  or removed. Stiffeners or reinforcing members  58  connected to the inside of the floor of the shield  44  extend transversely between opposite pivot locations. 
     The bracket and shield assembly  34  includes a transversely extending axle shield  60  connected to the forward face of the axle beam  16  by spaced upright brackets  62 . The brackets  62  support the axle shield  60  forwardly and partially below the beam  16   b  for movement with the front axle assembly  16 . The axle shield  60  is formed from a rigid sheet material, such as sheet metal, and includes a forwardly facing panel  60   a  that extends upwardly and forwardly from a rear horizontal lip  60   b  bolted at transversely spaced locations to the forward end  32 F of the shield  32 . As best seen in  FIG. 5 , the shield  32  extends under the beam  16   b  and under the lowermost rods  20   c . A top panel bent panel  60   c  extends upwardly and rearwardly from the panel  60   a.    
     A fixed shield  70  connected below the frame  12  by shield brackets  72  extends downwardly in the rearward direction from a location under a central portion of the engine compartment  22  and terminates in an aft end  70 R closely adjacent the axle shield  60 . The shield  70  provides a sloped transition area  74  under the engine compartment leading into the forward portion of the plant shield assembly  30 . Pivotal connections  78  with removable pivot pins  79  permit the forward shield  70  to be pivoted downwardly or removed in a manner similar to that for the pivoting shield  44 . 
     A contact surface  80  located between the flexible shield  32  and the rigid shield  44  at the first joint location  50  is in contact with the shields to reduce friction and wear on the portions of the shields that move adjacent one another. A formed sheet metal end connector  84  is connected by bolts  86  ( FIGS. 4 and 5 ) to the aft end  32 R of the sheet material  32 . The bolts  86  extend through apertures in the sheet material  32 , the connector  84  and a lower plate  88  ( FIG. 6 ). The end  32 R is sandwiched between the connector  84  and the lower plate  88 . Upturned sides  84   u  support upturned sides  32   u  formed in the sheet material  32  to define a generally channel-shaped and gapless shielding area which opens upwardly from the front axle beam  16   b  to the aft end  44 R of the shield  44 . The bolts  86  also support the forward ends of the connector structure  52 . 
     Anti-friction pads  90  formed from an ultra high molecular weight (UHMW) plastic material or other low friction wear material are mounted at the forward end of the central shield  44 , and the aft end of the connector  84  is slidably supported between the pads  90 . The pads  90  are sandwiched between the bottom panel of the shield  44  and a sheet metal pad support  94  connected by bolts  96  to the inside surface of the panel ( FIG. 6 ). As the axle moves relative to the frame  12 , the material  32  can flex and the connector structure  52  stretches as necessary to allow movement of the forward end of the connector  84  relative to the anti-friction pads  90 . The structure  52  maintains the material  32  taut. S-shaped connectors  52   c  may be selectively placed in different slot locations  56   c  to adjust the tension on the material  32  and accommodate different sheet material  32  and vehicle chassis configurations. As shown, the sheet material  32  is a PVG compound with embedded fabric, such as Goodyear material PVG-110S1-DDb-72. Alternatively, a tarp or rubber material having similar consistency and flexibility as the PVG material as well as other flexible materials could be used. 
     The aft wheel axle assembly or structure  18  is connected to the aft end of a second flexible shield  132  similar in construction to that of the forward shield  32  to define a generally continuous barrier between the plant growth and the frame  12  from the forward wheel axle assembly  16  to the aft axle assembly  18 . The flexible shield  132  includes a forward end  132 F attached by bolts  186  a connector  184  in a manner similar to that described above for the connector  84 . Resilient or stretchable connector structure  152  releasably connects the forward end  132 F to selected apertures  156  in the rigid or central shield  44 . A rear pad support  194  is bolted to the aft end of the shield  44  and supports anti-friction pads (not shown) in a manner similar to that described for the pads  90  described above. 
     The shield  132  is similar to the shield  32  and includes an aft end  132 R connected to an axle shield assembly  134 . Brackets  162  are bolted to the aft wheel axle assembly  18  so the assembly  134  supports the aft end  132 R of the rear flexible shield  132  under the axle beam  18   b  and moves with the axle assembly  18  as it rocks relative to the frame  12 . The shield  132  can flex as necessary to allow unrestricted rocking of the axle relative to the frame over the entire range of axle movement. The connectors  152  maintain the shield  132  taut under the frame  12  and under the rear axle support structure. 
     As best seen in  FIGS. 3 and 4 , the under-frame plant shield assembly  30  has a wasp-waist configuration that opens upwardly towards the underside of the vehicle  10  and provides generally continuous and seamless protection from the forward wheel axle assembly  16  to the aft wheel axle assembly  18 . The forward fixed shield  70  extends the protection from the shield assembly  34  forwardly to a location under the engine compartment  22 . Access to any location under the frame  12  is easily provided by the versatile pivotal mounting of the central shield  44  to the frame  12  and the releasable connector structure  52  and  152 . 
     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.