Abstract:
In a header having a movably mounted knife and a guard for shielding the moving and rotating components operating the knife, the guard preferably comprising two interconnected parts of which the first part is mounted on the header so as not to move with the knife and the second part is coupled for movement with the knife. In this way, the area shielded by the guard automatically expands and contracts with movement of the knife.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/684,930, filed May 25, 2005. 

   FIELD OF THE INVENTION 
   The present invention relates to a guard for a header of a harvester, in particular a header having an adjustably mounted knife. 
   BACKGROUND OF THE INVENTION 
   In some headers of a combine or forage harvester, crop is cut near the ground by an oscillating cutter. Though the cutter may use a scissoring action, it is commonly referred to as a “knife” and this term will be used herein to include any form of cutter. A reel with tines rotates in front of the knife about a horizontal axis to gather the cut crop and to drive it onto an auger which advances the crop towards the vehicle centerline. From there, conveyors carry the crop into the processing machinery. In the case of a combine harvester, the processing machinery separates the grain from the stalks and the chaff. The grain is stored in a grain tank while the stalk and the chaff are discharged from the rear of the harvester. In a forage harvester, the processing machinery chops the entire crop into small pieces and discharges it from a spout into a second vehicle driven alongside the harvester. 
   Commonly, the knife is mounted in a fixed position on the header and the various rotating and moving parts that drive the knife are covered by a guard. The guard is constructed as a door which can be hinged open to allow access to the parts which drive the knife. These parts include the so-called “wobble box,” which reciprocates a blade of the knife, and the pulley driving the wobble box. 
   In some headers, the knife can be moved forwards and backwards from a central position by about 50 cms. In headers having an adjustably mounted knife, a problem is encountered because the movement of the knife can result in some rotating and moving parts becoming exposed, as they are no longer shielded by the guard. 
   SUMMARY OF THE INVENTION 
   With a view to mitigating the foregoing disadvantage, the present invention provides a header having a movably mounted knife and a guard for shielding moving and rotating components operating the knife, wherein the guard is formed of two interconnected parts of which the first is mounted on the header so as not to move with the knife and the second is coupled for movement with the knife, whereby the area shielded by the guard expands and contracts with movement of the knife. 
   Preferably, the first part of the guard is hinged on the header (i.e. the header frame) and the second part is mounted for sliding movement relative to the first part. More specifically, a half-hinge, or any other suitable type of hinge, is affixed to the header frame, and another half-hinge is affixed to the first part of the guard. Both half-hinges are interconnected by any suitable means, such as a hinge pin. 
   To enable the sliding movement between first and second parts of the guard, the first part of the guard may comprise upper and lower parallel supports for the second part and at least one of the supports is formed as a runner which receives rollers mounted on the second part. 
   For example, the upper rail could comprise a bracket of L-shaped section on the first part engaged by a bracket of inverted L-shape section on the second part, the limbs of the two brackets interlocking with one another to prevent separation of the parts without supporting the weight of the second part on the first part. This makes for a less expensive construction that is easy to assemble and avoids problems if the two support brackets are not accurately aligned parallel to one another. The lower rail runner or track could be C-shaped to receive roller wheels. 
   It is contemplated that the lower rail of the first part of the guard may contain a device to prevent the first part and the second part of the guards from separating. Preferably, the rail can include an upright rod at its rear end. Additionally, the roller wheels, which cooperate with the lower rail, can include a U-shaped safety lock, preferably made of spring steel, which is intended to receive the upright rod through interference fit. 
   This safety lock will catch over the rod on the first part of the guard and release when sufficient force is applied. The aim of this lock is that, when the guard is opened, the operator can slide the first part fully backwards so the safety lock catches, and the guard will not slide forward or backward on its own. Pulling the second part of the guard forward with enough force will release the safety lock and allow the guard to be closed on the header again. 
   In the preferred embodiment of the invention, the second part of the guard is also formed with a catch that is releasably engaged by a component that moves with the knife, so that the two parts of the guard automatically slide relative to one another with movement of the knife. Release of the catch permits the two parts of the guard to be pivoted together relative to the header. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a conventional header having a header assembly including a header frame and guard; 
       FIG. 2  is a left side view, relative to a forward direction of travel T of the harvester (this direction allocation hereinafter inherent in all figure descriptions), of the first and second part of the guard of the invention; 
       FIG. 3  is a left side skeleton drawing of the guard in conjunction with the header frame of  FIG. 2 ; 
       FIG. 4  is a section view, taken along lines  4 - 4  in  FIG. 3 , through the upper of two supports connecting the two parts of the guard of  FIG. 3  to one another; 
       FIG. 5  is a section view, taken along lines  5 - 5  in  FIG. 3 , through the lower of the two supports connecting the two parts of the guard of  FIG. 3  to one another; 
       FIG. 6  is a left rear view of the lower support of  FIG. 5 , showing the safety lock of the guard and header frame of  FIG. 2 ; 
       FIG. 7  is a left side view of the header frame of  FIG. 2 , with the guard removed, illustrating the locking stirrup and locking pin aperture of the present invention; 
       FIG. 8  is a front left view of the header frame of  FIG. 7 , with the guard removed, illustrating the locking stirrup and locking pin aperture of the present invention; 
       FIG. 9  is a front right inside view of the guard of  FIG. 2 , illustrating the locking pin and dampers of the present invention; 
       FIG. 10  is an additional front right inside view of the guard of  FIG. 2 , illustrating the locking pin, dampers, and latch mechanism of the present invention; 
       FIG. 11  is a front right inside view of the guard of  FIG. 2 , illustrating the latch mechanism of the present invention; 
       FIG. 12  is a top view of the guard of  FIG. 2  in conjunction with the header frame at a beginning closing position “A”, illustrating the locking pin and dampers of the guard interacting with the locking stirrup and locking pin aperture of the header frame; 
       FIG. 13  is a top view of the guard of  FIG. 2  in conjunction with the header frame at an intermediate closing position “B”, illustrating the locking pin and dampers of the guard interacting with the locking stirrup and locking pin aperture of the header frame; 
       FIG. 14  is a top transparent view of the guard of  FIG. 2  in conjunction with the header frame at a final closed, locked position “C”, illustrating the locking pin and dampers of the guard with the locking stirrup and locking pin aperture of the header frame; and 
       FIG. 15  is a top, outside transparent view of the locking stirrup of the header frame secured in place within the latch mechanism of the guard of  FIG. 2 , further illustrating the interaction of the locking pin and dampers with the locking pin aperture of the header frame and a hex knob accessible from the outside of the guard to unlock the guard from the header frame. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The header  10  shown in  FIG. 1  has a crop cutter or knife  12  arranged close the ground. The knife comprises a stationary blade and a reciprocating blade which together act as shears which cut the crop near the ground. A reel  14  having tines  16  rotates about a horizontal axis next to the knife  12  to gather the cut crop and feed it into the processing machinery of the harvester (not shown). 
   At one end only of the header, there is provided a wobble box  80  (shown in  FIG. 8 ), which reciprocates the movable blade of the knife  12 . The wobble box  80  is driven by means of a drive belt  82  and a drive pulley  84 , which are shielded by means of a guard  18 . This serves to prevent crop from becoming entangled in the drive train of the wobble box  80  and also avoids the risk of injury to a person standing nearby. To allow access to the wobble box  80  and its drive train for servicing, the guard  18  is designed as a door which can be hinged open at its rear end and is kept closed by a catch at its front end. 
   The header shown in  FIG. 1  has a fixed knife. There are other headers, however, in which the knife  12  can be moved forwards and backwards to each side of a central position, through a distance of as much as, for example,  40  cms. In such a header  10 , the guard  18 , as shown in  FIG. 1 , is not sufficiently large enough to shield the wobble box  80  and its drive train when the knife  12  is in its forward position. 
   The preferred embodiment of the invention, which will now be described by reference to  FIGS. 2-15 , mitigates the above problem by providing a guard  18  having a variable geometry, to be effective in all positions of the knife  12 . As illustrated in the left side view (relative to a forward direction of travel T of the harvester) of  FIGS. 2-3 , the guard  18  is formed of a first part  20 , which is mounted on a stationary component of the header (i.e. header frame) by means of a hinge  24 . The guard  18  also comprises a second part  22 , which is slidably carried on the first part  20  by means of two supports  30  &amp;  36 , which will be described below in greater detail. 
   A catch  40 , which is shown in more detail in FIGS.  2  and  7 - 15 , releasably connects the front end of the second part  22  of the guard  18  for movement with the knife  12 . In this way, as the knife  12  moves forwards and backwards, it causes the second part  22  of the guard  18  to slide relative to the first part  20  so that the wobble box  80  and its drive train ( FIG. 8 ) always remain shielded. 
   As can be seen from the section view of  FIG. 5 , the lower support  30  for the second part  22  of the guard  18  preferably comprises rollers  32  secured to the second part  22 , which are held captive within, and slide along, a lower rail  34 , such as a runner or track, affixed to the first part  20 . Rollers and runners are of course commonly used in many applications, for example to mount drawers in furniture, and it is not therefore deemed necessary to describe them in detail. Their use provides a smooth and silent sliding action. Furthermore, because the rollers  32  are held captive in the runner  34 , they prevent relative movement between the two parts  20 ,  22  in the vertical plane. 
   If one of the two supports  30  is formed by rollers  32  guided in runners  34 , the second  36  need only be designed more simply, as shown in the section view of  FIG. 4 , as two L-shaped brackets  38  &amp;  39  having limbs which engage one behind the other. Such engagement prevents the two parts  20 ,  22  from being separated from one another but does not serve to support the weight of the second part  22 . Aside from reducing cost, such a construction makes parallel alignment of the two supports  20 ,  22  less critical. 
   Turning now to  FIG. 6 , it is preferred that the runner or track  34  of the first part  20  of the guard  18  contains a device  50  to prevent the first part  20  and the second part  22  of the guards  18  from separating at both ends. Preferably, this device  50  could be an upright rod  52  mounted at the front and rear ends of the lower runner or track  34 . In reference to the rear end of the lower runner or track  34 , the support of the rearmost roller wheels  32  can include a U-shaped safety lock  54 , preferably made of spring steel, which receives the rearmost upright rod  52  by an interference fit. 
   This safety lock  54  will catch over the rod  52  on the first part  20  of the guard  18  and release when sufficient force is applied. The aim of this lock  50  is that, when the guard  18  is opened, the operator can slide the second part  22  fully backwards so the safety lock  54  catches, and the second part  22  of the guard  18  will not slide forward or backward on its own. Pulling the second part  22  of the guard  18  forward with enough force will release the safety lock  54  and allow the guard  18  to be closed on the header  10  again. 
   Turning now to  FIGS. 7-15 , the catch  40  is intended to serve two purposes. First, it couples the second part  22  of the guard  18  to the front section of the header frame  10  for movement with the knife  12 . Second, it supports the weight of the guard  18  because, when the guard  18  is extended to its maximum length, it can place undue stress on the hinge  24 . Thus the catch  40  prevents movement of the front end of the guard  18  in two mutually perpendicular planes. 
   To ensure that the second part  22  of the guard  18  moves horizontally with the knife  12 , a U-shaped locking stirrup  42  is bolted to a plate  44  attached to the front section of the header frame  10  so that it moves with the knife  12 . The free ends of limbs of the locking stirrup  42  are preferably threaded and are secured to the plate  44  by means of nuts  45 . This method of fixing enables the amount that the stirrup  42  projects from the plate  44  to be adjusted. However, it should be realized that other suitable methods of affixing the locking stirrup  42  to the plate  44  are also contemplated. 
   To support the weight of the free end of the guard  18  and prevent it from moving vertically, the header frame also includes a locking aperture  43  formed in the base plate  44  of the stirrup  42 . The locking aperture  43  includes a bushing, which is mounted thereto. The bushing preferably is made out of plastic material, such as polyamide. 
   The interior of the second part  22  of the guard  18  includes a locking pin  46  having a preferably conical point, two dampers  47 , which may be formed of rubber or any other dampening material, and a latch mechanism  48 , which has an access knob  49  accessible to the exterior of the second part  22  of the guard  18 . The latch mechanism  48  may be constructed in a manner similar to latch mechanisms used on motor vehicles to hold down the hood or the lid of a trunk. 
   In operation, such as when it is desired to close the guard  18  from an open position, the first part  20  of the guard  18  is hinged towards a closed position and when nearly closed the second part  22  is slid to the extent necessary to align the locking pin  46  with the bushing of the locking aperture  43  in the plate  44 . The locking pin  46  fits within the bushing and locking aperture  43 , such that the header frame bears the loads generated by sliding both parts  20 ,  22  of the guard  18  relative to each other. The second part  22  of the guard  18  is then pushed shut so that the latching mechanism  48  engages with the locking stirrup  42 . 
   In addition to the above, the two rubber dampers  47 , which are preferably mounted at an angle to each other (i.e. in a V-shape), touch a corresponding surface on the front section of the header frame  10  when the second part  22  of the guard  18  is closed. These dampers  47  are adjusted in such a way that they are slightly compressed when the guard  18  is closed. This arrangement provides additional vibration suppression (the reciprocating movement of the header knife  12  creates vibrations, which tend to propagate through the header  10  and can lead to premature failures and excessive noise generated by the plates of the guard  18 ). Once the catch  40  is engaged, the wobble box  80  and its drive train  82 ,  84  will automatically remain adequately shielded in all positions of the knife  12 . 
   When access to the wobble box  80  is required for servicing, the guard  18  can be opened in the same way as the guard  18  in  FIG. 1 . In particular, the latch mechanism  48  must first be released. Release of the latch mechanism  48  can occur at a single access point, a luxury not afforded by the prior art. 
   It is contemplated that the present invention may employ a variety of latch mechanisms  48 , such as those that may be released remotely either electrically or mechanically, for example using a Bowden cable. Additionally, and as shown in  FIGS. 14 and 15 , the latch mechanism can be released mechanically through “an action”, that is, through the turning of a knob  49  from the exterior of the second part  22  of the guard  18 . Preferably, this knob  49  has a hexagonal or other distinctive shape, which requires a specific tool to actuate it, such that it cannot be opened by inadvertent by-passers. 
   Thus, to open the guard  18 , the operator can simply turn the knob  49  on the lock to any pre-set, desired range, such as about 45 degrees, and pull the shield  18  toward him, thereby disengaging the locking stirrup  42  from the latching mechanism  48 . Alternatively, the latch mechanism  48  may simply be a spring latch designed to release the locking stirrup  42  when the guard  18  is released from its closed position. 
   In reference to  FIG. 3 , after the catch  40  is released through actuation of the latch mechanism  48 , the operator can then slide the second part  22  of the shield  18  backwards until the safety lock  50  at the back catches and then the two parts  20 , 22  of the guard  18  can be swung open about the hinge  24 .