Abstract:
The assembly comprises a beam, a support wheel rotatably mounted on an axle carried by the beam with a stub shaft. A hole in the frame of the baler which receives the stub shaft includes at least one radial recess dimensioned to permit the radially projecting arm to pass through the hole when aligned with the recess, the arm preventing the stub shaft from moving axially relative to the frame when misaligned with the recess.

Description:
This application is the US National Stage filing of International Application Serial No. PCT/EP2011/056541 filed on Apr. 26, 2011 which claims priority to Belgium Application BE2010/0329 filed May 31, 2010, each of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a pick-up support wheel assembly for an agricultural machine, such as a baler or a forage harvester. 
     BACKGROUND ART 
     A baler is an agricultural machine, usually towed by a tractor, that picks straw, or other crop material, from the ground and ties it into round or square bales. The straw will usually have been deposited on the ground in windrows, or swaths, by a combine harvester. 
     The mechanism used to pick up straw substantially comprises a frame supported on wheels on the ground and carrying a rotating hoe and a chute for guiding the straw picked up by the hoe towards a baling chamber. 
     The width of the hoe should be as wide as possible to maximise the width of the tract of land from which straw is gather during each pass of the baler. However, the support wheels must be positioned outside the area swept by the hoe and it is their distance apart that determines the maximum width of the baler. As any vehicle that is to be towed on public roads must comply with maximum width requirements, leaving the support wheels in place during transportation of the baler places a limit on the width of the pick-up hoe. 
     It has therefore been proposed previously to remove the pick-up support wheels from the frame of the pick-up during transportation. However, in known balers where this is possible, the removal and mounting of the pick-up support wheels is a cumbersome task requiring tools. 
     For example, EP 1179294 discloses a wheel assembly for supporting a frame of a pick-up of an agricultural baler on the ground, which, in common with the present invention, comprises a beam, a support wheel rotatably mounted on an axle carried by the beam, a stub shaft on the beam receivable in a hole in the frame for pivotably and releasably mounting the beam on the frame of the pick-up and a locking mechanism for locking the beam in a desired position relative to the frame to set the height of the frame above the ground. In the latter patent, after inserting the stub shaft in aligned holes in the frame, it is necessary to mount a retaining collar on the end of the stub shaft projecting from the inboard side of the frame. To do this, the operator is required first to gain access to the inboard end of the stub shaft while it is in situ. After slipping the retaining collar over the end of the stub shaft, a pin must be inserted through diametrically aligned holes in the collar and the stub shaft and finally a fastening must be fitted to the pin to retain it within the collar. 
     SUMMARY OF INVENTION 
     The present invention seeks to provide a pick-up wheel assembly which simplifies the tasks of mounting and dismounting the support wheels and avoids the need for tools. 
     In accordance with the present invention, there is provided a wheel assembly for supporting a frame of a pick-up of an agricultural baler on the ground, comprising a beam, a support wheel rotatably mounted on an axle carried by the beam, a stub shaft on the beam receivable in a hole in the frame for pivotably and releasably mounting the beam on the frame of the pick-up and a locking mechanism for locking the beam in a desired position relative to the frame to set the height of the frame above the ground, characterised in that a retention plate is provided on the end of the stub shaft having at least one arm projecting beyond the circumference of the stub shaft and the hole in the frame for receiving the stub shaft includes at least one radial recess dimensioned to permit the at least one radially projecting arm to pass through the hole when aligned with the at least one recess, the at least one arm preventing the stub shaft from moving axially relative to the frame when misaligned with the at least one recess. 
     Conveniently, the retention plate has a plurality of circumferentially spaced radially projecting arms, resembling a star shape, the hole in the frame having a cross section with a complementary outline. 
     It is preferred for the arms not to be equally spaced circumferentially, so that the retention plate only aligns fully with the hole in the frame once in every full rotation of the retention plate through 360°. If three arms are evenly distributed about the circumference of the retention plate, this would allow secure retention only over an angular rotation range of 120°, but this may suffice in practice as it exceeds the adjustment range of the beam. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a support wheel assembly mounted on the frame of a pick-up of a baler, as viewed from the outboard side of the frame, 
         FIG. 2  is a perspective view of the support wheel assembly when removed from the frame, the drawing showing its side facing the frame of the pick-up, 
         FIG. 3  is perspective of the support wheel assembly when mounted on the frame of a pick-up as viewed from the inboard side of the frame with parts of the frame being cut away to show the manner in which the support wheel assembly is mounted on and retained by the frame of the pick-up, and 
         FIG. 4  is a section through the beam in a plane passing through the axis of the locking pin. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a pick-up  10  of a baler having a frame  12  carrying a rotary hoe of which only the tines  14  can be seen in the drawing. The design and function of the pick-up  10  may be conventional and need not be described within the present context. It suffices to understand that the pick-up is towed along the ground and that the frame  12  is supported by an adjustable and removable wheel assembly  20 . The adjustability of the wheel assembly  20  is to allow setting of the height of the hoe above the ground and its removability is to enable the width of the baler to be reduced when it is towed on a public road. 
     The support wheel assembly is shown in  FIG. 2  separated from the frame  12  of the baler pick-up  10 . The wheel assembly  20  comprises a beam  22  and a wheel  24  rotatable about an axle  26  secured to one end of the beam  22 . Intermediate its end, the assembly  20  comprises a stub shaft  28 , which lies on the opposite of the beam  22  from the wheel  24 . A star-shaped retention plate  30  with three radially projecting arms is fixed to the inboard end of the stub shaft  28 . At its opposite end from the wheel  24 , the beam  22  carries a resiliently retractable locking pin  32  which can engage in one of several holes  16  formed in the frame  12 . 
     As shown in  FIG. 4 , the locking pin  32  has a shank  320  that passes through two aligned holes  322  and  324  in the beam  22 . The hole  324  on the frame side of the beam  22  is larger than the other hole  322  so that it can accommodate a compression spring  326  surrounding the shank  320 . The spring  326  is compressed between the beam  22  and a head  328  of larger diameter than the shank  320  that engages in one of the holes  16 . The pin  32  is assembled into the beam  22  by first placing the spring  326  over the shank  320  and inserting the shank  320  into the hole  324  until its end  330 , which is externally threaded, protrudes through the hole  322 . An actuating knob  332  that is used to retract the pin  32  is then screwed onto the threaded end  330  of the shank  320 . 
     As shown in  FIG. 3 , when the support wheel assembly  20  is mounted on the frame  12 , the stub shaft passes through two aligned holes  42  and  44  in two spaced plates  12   a  and  12   b  of the frame  12  which support the outboard and inboard end of the stub shaft  28 , respectively. The holes  42  and  44  are of the same shape as the retention plate  30  and dimensioned to allow the retention plate  30  to pass through them with clearance when the arms of the retention plate  30  are aligned with the radial recesses of the holes  42  and  44 . 
     To fit the support wheel assembly  20  to the frame  12 , the stub shaft  28  is offered to the holes  42  and  44  and the assembly  20  is rotated about the stub shaft  28  to the extent necessary to align the retention plate  30  with the hole  42 . This requires the assembly  20  to be rotated anticlockwise as viewed in  FIG. 2  and is effected by raising the wheel  24  above ground level. 
     With the wheel assembly held in this orientation, the stub shaft  28  is next pushed into position, the retention plate  30  passing first through the hole  42  in the plate  12   a  then the similar hole  44  in the plate  12   b . Once the stub shaft  28  has passed through both the plates  12   a  and  12   b , the wheel is released and it drops to ground level the stub shaft  28  is rotated into the position shown in  FIG. 3 . In this position, the retention plate  30  is misaligned with the hole  44  and prevents the wheel assembly  20  from being withdrawn from the frame  12 . 
     With the wheel assembly  20  securely attached to the frame  12 , the desired height of the frame  12  above the ground can be set by rotating the wheel assembly  20  to its desired position about the stub shaft  28  and locking it in position by manually retracting the locking pin  32  and releasing to engage under the action of its own spring force in the appropriate one of the holes  16  in the frame  12 . 
     Removal of the support assembly can also be achieved without the use of any tools. After release of the locking pin  32 , the wheel  24  is raised off the ground to rotate the stub shaft  28  to the position in which the star-shaped retention plate  30  aligns with the hole  44 . The stub shaft  28  may then be slid out to release the support wheel assemble  20  from the frame  12 . 
     It will be appreciated that it is only necessary for the retention plate to have one radially projecting arm but it has been found that three distributed arms are to be preferred in that they provide improved retention without unduly weakening the holes  42  and  44  which withstand the forces acting on the stub shaft. If the three arms are evenly spaced, the beam can only be rotated through 120° without risk of it separating from the frame  12 . For this reason it is preferred for the spacing to be uneven so that alignment of the arms with the hole in the frame only occurs in one relative angular position.