Abstract:
A sliding shield structure is attached to the rod of a steering cylinder and moves with the rod to fully protect the rod at all times and to eliminate interference between the shield and steerable wheel throughout the steering range of the implement. Primarily support of the shield is by the implement axle structure, rollers and slides. The shield and the rod can rotate freely relative to each other to eliminate torque load transmission between the components. A notched plate holds the structure and facilitates easy removal by simply rotating the shield away from the cylinder rod.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to steering systems for off-road vehicles such as agricultural harvesters and, more specifically, to shielding for such steering systems. 
   BACKGROUND OF THE INVENTION 
   In the design of steering systems, using one double-acting cylinder connected to each wheel spindle is advantageous compared to more expensive and complicated two-cylinder systems. One problem with single cylinder systems is that the cylinder needs to be placed on the front side of the axle to optimize steering characteristics. For example, the Ackerman error can be reduced significantly by a front mounted arrangement. However, in such an arrangement the cylinder becomes exposed to crop passing beneath the machine. Cotton harvesting occurs when the plant stalk is still quite green, and therefore the cylinder rod must be protected from plant sap. If the rod is unprotected, sap builds up on the rod and causes premature seal failure. The geometry of the steering system is such that the space in which the cylinder rod extends is also the same space that is encroached by the tire and wheel when the cylinder is moved in the opposite direction. As a result, fixed shielding is rather ineffective. If the shield is made narrow enough to avoid the tires and wheels in sharp turns, cylinder rod protection from the crop is insufficient. Flexible accordion shields tend to collect dirt and debris, are easily damaged and have to operate effectively from a short closed length to a relatively long extended length. Removal of such shields for servicing and cleaning is difficult and time-consuming. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide an improved cylinder shield structure for an off-road implement such as a harvester. It is another object to provide such a shield which overcomes most or all of the aforementioned problems. 
   It is another object to provide an improved cylinder shield structure for a steering system of an off-road implement. It is a further object to provide such a system which is particularly useful for a single cylinder steering system and for a front-mounted cylinder steering system. It is another object to provide such a structure which is simple, reliable and easy to remove and attach. It is a further object to provide such a system which protects cylinder rod structure over substantially the entire range of steering angles. 
   A sliding shield structure is attached to the rod of a steering cylinder and moves with the rod. The rod is therefore fully protected at all times and does not interfere with tire and wheel at any point in the full steering range of the implement. Primarily support of the shield is by the implement axle structure using rollers and slides. The shield and the rod can rotate freely relative to each other to avoid introduction of unwanted torque loading between the shield and the rod. A notched plate and notched retainer hold the structure and facilitate easy removal by simply rotating a notched retainer away from rod. The shield structure is particularly useful with front-mounted, single cylinder steering systems wherein unwanted contact between the cylinder and vegetation or other obstacles passing under the implement frame could damage the systems. 
   These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon reading the following description in view of the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is top view of a steerable axle assembly with a steering cylinder and protective shield. 
       FIG. 2  is a view similar to that of  FIG. 1  but showing the steerable axle assembly steered to a full right turn position. 
       FIG. 3  is a view similar to  FIG. 2  but showing the steerable axle assembly steered to a full left turn position. 
       FIG. 4  is an enlarged perspective view of a portion of the shield and cylinder support. 
       FIG. 5  is an enlarged perspective view showing details of the roller and slide support for the shield. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIGS. 1–3 , a steerable axle assembly  10  for an off-road vehicle or implement such as a cotton harvester includes an axle frame  12  connected to the implement frame (not shown) and right-hand and left-hand steerable wheel assemblies  16  and  18  pivotally connected to the ends of the axle frame  12 . The axle frame  12  is offset above the ground and is adapted for forward movement F over plant material in the field. Steering structure indicated generally at  20  rotates the wheel assemblies about upright pivotal axes over a range of steerable positions from an extreme right-turn position ( FIG. 2 ) through a straight-ahead position ( FIG. 1 ) to an extreme left-turn position ( FIG. 3 ). The entire axle assembly is pivotable about a generally fore-and-aft extending axis  22   a  ( FIG. 1 ) to better follow the ground contour. 
   As shown in  FIGS. 1–3 , the steering structure  20  includes a front-mounted, single steering cylinder  24  with left and right cylinder rods  26  and  28  connected by conventional steering linkages  36  and  38  to the respective wheel assemblies  16  and  18 . The steering structure  20  also includes a non-stationary shield assembly  40  supported forwardly of the cylinder  24  and protecting the cylinder and rods  26  and  28  from damage by plant or other material that the axle assembly may encounter in any of the positions over substantially the entire steering range without interfering with the wheel assemblies  16  and  18 . 
   Cylinder and shield support structure  50  is bolted to the axle frame  12  and includes a pair of lower forwardly projecting horizontal plate structures  52  and upright plate structures  54 . The plate structures  54  are apertured and spaced transversely to receive the ends of the barrel of the cylinder  24 , and bolted brackets  56  secure the ends of the barrel forwardly of the frame  12  with the axis of the cylinder lying generally parallel to the frame  12 . The cylinder  24  includes opposite ports  66  and  68  located adjacent the opposite ends of the barrel of the cylinder  24 . The ports and the ends of the hydraulic lines connected to the ports are also protected by the shield assembly  40 . Pressurizing the cylinder port  66  moves the rods  26  and  28  to the left to turn the wheel assemblies  16  and  18  towards the left ( FIG. 3 ), while pressurizing the port  68  turns the wheel assemblies the opposite direction. 
   The shield assembly  40  includes a one-piece channel shaped shield member  70  opening rearwardly towards the cylinder  24  and including top, front and bottom walls  72 ,  74  and  76 . An upwardly projecting flange  78  extends from the aft portion of the wall  72  to provide stiffening and added shielding. An upright support plate  80  and gusset  82  are secured to the opposite ends of the member  70  between the walls  72  and  76 . The aft portion of the plates  80  include rearwardly opening notches or slots  86  ( FIG. 4 ) just inwardly of corresponding enlarged portions  88  at locations adjacent the pivotal connection of the steering linkages  36  and  38  to the rods  26  and  28 . Retainers  90  are connected to the plates  80  by bolts  92 , and each includes a downwardly opening notch or slot  96  received over the rod end to retain the plate  80  on the rod end. The retainers  90  secure the opposite ends of the shield member  70  to the rods  26  and  28  and constrain the shield member  70  to move laterally with the rods while allowing relative rotation between the rods and the shield member  70  to eliminate unwanted torque transmissions between the rods and the shield assembly  40 . The shield member  70  can be detached by simply removing the upper bolts  92  and rotating the retainers  90  upwardly about the lower bolt  92 . If desired, the upper bolts  92  can be eliminated and the lower bolts lightly tightened to allow the retainers  90  to pivot by hand so that the shield assembly can be attached and removed without tools. 
   To maintain the shield member  70  in a protective position and facilitate transverse movement of the member relative to the frame  12  with steering of the wheel assemblies  16  and  18 , a pair of roller support members  100  are secured to the plate structures  52  near the opposite ends of the barrel of the cylinder  24 . Each roller support member  100  includes an angle bracket  102  connected by bolts  103  to the forward end of the corresponding plate  52 . Rollers  104  are rotationally supported by bolts  105  on upstanding legs on the bracket  102  for contacting the underside of the wall  72  and supporting the shield member  70  for transverse movement relative to the support members  50  and frame  12 . Upper forward slides  106  supported from the legs by the bolts  105  opposite the rollers  106  and downwardly facing slides  108  supported by the bolts  103  provide low friction, positional support for the shield member  70 . 
   In operation, as the rods  26  and  28  are moved to steer the implement, the plates  80  and gussets  82  fixed to the shield member  70  move in unison with the rods to move the shield member. The upper wall is supported on the rollers  104  which rotate as the shield member  70  moves to the left or right with the rods  26  and  28 . The rollers  104  and slides  106  and  108  provide good positional support and ease of shield movement, and the slotted connections at the plates  80  constrain the shield member for movement with the rods  26  and  28  without transferring torque between the members. The shield member  70  can be removed for maintenance and repair by simply removing the slotted retainers  90  and sliding the slotted plates  80  off the rods  26  and  28 . As can best be seen in  FIGS. 2 and 3 , the shield member  70  provides effective shielding for the cylinder and cylinder rods over the entire range of steerable positions of the wheel assemblies  16  and  18 . The movement of the shield member  70  with the steering of the implement assures that the shield member remains out of contact with the wheel assemblies at all steering positions in the range. The shield assembly  40  facilitates mounting of single cylinder steering systems on the front side of the axle to optimize steering characteristics. 
   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. For example, although the shield assembly is shown with a single cylinder front mounted steering system, it is possible to utilize the movable shield arrangement with a variety of cylinder or actuator arrangements where movement of a shield with actuation is advantageous to provide effective protection.