CUTTER BAR FOR DISC MOWER

Abstract: A cutter bar (10) for a multi-disc mowing machine having a number of mower discs (17) spaced apart along the length of the cutter bar and in which: the cutter bar (11) has an external mounting plate (12) having spaced apart mounting locations (16) on which respective mower discs (17) are mounted to rotate about vertical axes (18); a gear box housing (19) is mounted externally of the cutter bar (11) at each mounting location (16) to mount a respect mower disc (17) thereon; torque transmitting elements (25) are located externally of the cutter bar (11) and arranged to transmit torque between an adjacent pair of gear box housings (19); and a drive input (20) is arranged to receive power input from a vehicle propelling the mowing machine and to transmit torque to the gear box housings (19) via the torque transmitting elements (25).

Description: CUTTER BAR FOR DISC MOWER This invention relates to a cutter bar for a disc mower. An agricultural disc mower is used to cut a standing crop of grass, and to deposit the mown crop in a swath where it is allowed to dry at least partly. The cutter bar of a disc mower extends perpendicular to the mowing direction, and has a number of rotary mower discs arranged along its length, and which are driven to rotate in required alternate directions by a gear-drive train which usually receives power input from the PTO shaft of a tractor which is used to propel the disc mower. It is usual to mount a series of gears internally of the cutter bar, and which are arranged along its length and which form the gear drive tram which applies required rotation to the mower discs. The power input is usually applied to an input gear at one end of the cutter bar, and rotary drive is then transferred from one gear wheel to another and throughout the length of the cutter bar. Each mower disc is driven by a respective gear of the drive train, and since the power input to the gear drive train must be sufficient to apply driving torque to all of the mower discs, substantial torque is transmitted via the gear train within the cutter bar. While it is true that the torque delivered to each successive mower disc will reduce the remaining torque transmitted to the next mower disc (so that in theory the gear train could be designed to have maximum torque transmission capacity at the input end and with progressive reduction in strength along the length of the cutter bar), in practice the gears installed in the cutter bar are of uniform design and strength to achieve economies of scale in stocking, installation, and supply of spare parts. Therefore, given that at least the input gear is required to transmit torque sufficient to drive all of the mower discs, this means that the gears within the cutter bar have to be of sufficient size and strength to transmit this torque. Since the gears are mounted internally of the cutter bar, this means that the interior of the cutter bar must be of sufficient size to accommodate the gears of the drive tram, and this therefore requires the cutter bar to be of large cross-sectional area, and consequently increased weight and cost. The internal assembly of gears in a cutter bar is presently achieved in either one of two mam known types of installation. In a first known installation, the cutter bar is assembled from a number of cutter bar housings each incorporating a respective gear drive to operate a corresponding mower disc, and these housings are bolted or otherwise secured together side-by-side to form the cutter bar. These housings are separately manufactured and have to be of sufficient strength to be able to be secured together to form a unitary cutter bar of sufficient strength. In a second known installation, the cutter bar is formed from metal plate of generally rectangular cross-section, and of relatively shallow depth (a low height), to receive a succession of gears which are located in generally horizontal planes so as to rotate about generally vertical axes. It is usual to insert the gears, one by one, from one end of the cutter bar, and to move the gears along the interior of the cutter bar until they take up the required positions so as to apply driving torque to the mower discs. This is a time consuming task, since it requires careful manual manipulation of the gear wheels, so as to take up required positions along the length of the cutter bar, and to remain in mesh with each other. The two ma existing cutter bar gear arrangements are expensive and/or time consuming to assemble, but in addition when gear damage or unacceptable gear wear occurs at any particular point along the length of the cutter bar, so that gear replacement is necessary, disassembly of the cutter bar has to take place from one end of the cutter bar and up to the particular point at which replacement is required. Furthermore, special formations have to be provided in the upper face of the cutter bar, to tor suitable drive mountings for each rotatable mower disc. The present inventions seeks to provide an improved gear assembly for use with a cutter bar, in a way which a) simplifies assembly to the cutter bar and b) which allows a simplified (and therefore less costly) design of cutter bar formation to be utilised. According to the invention there is provided a cutter bar for a disc mowing machine having a plurality of mower discs which are required to be mounted at spaced apart positions along the length of the cutter bar, and to be driven by a gear drive train associated with the cutter bar, in which: a) the cutter bar is intended to be mounted on the mowing machine so as to extend generally perpendicular to the mowing direction and generally parallel to the surface of the ground over which the machine is travelling when drawn behind a propelling vehicle; b) the cutter bar has an external mounting face which is provided with a number of mower disc mounting locations which are spaced apart along the length of the cutter bar, each location being adapted to provide a mounting for a respective mower disc whereby the latter can be driven to rotate about an upwardly extending axis which is generally perpendicular to the axis of the cutter bar; c) a respective gearbox housing is mounted externally of the cutter bar at each of said mounting locations, each housing being adapted to mount a respective mower disc thereon so as to be capable of applying driving torque thereto; d) torque transmitting elements are located externally of the cutter bar and each arranged to transmit torque between an adjacent pair of gearbox housings; and e) a drive input is arranged to receive power input from said propelling vehicle, and to transmit torque to the gearbox housings via the torque transmitting elements. The invention therefore provides a cutter bar and gear train assembly which can have any suitable cutter bar design of relatively simple and cheap fabrication or construction (since it is not required to mount the gear train internally), and in which assembly, and disassembly of component parts of the gear tra can take place simply and without being dependent upon successive assembly, or disassembly, of adjacent gear tra components . Thus, the gearbox housings can be mounted separately on the respective cutter bar mountings, and then the drive- coupling between adjacent pairs of housings is usually achieved by external coupling together of the housings by respective torque transmitting elements. Also, by providing simple mounting locations for the gearboxes on the mounting face of the cutter bar (e.g. mounting holes in a front face of the cutter bar), the mounting locations are spaced apart from each other by distances corresponding to the diameter of the mower discs, and the lengths of the torque transmitting elements (e.g. shafts) will be selected according to the spacing apart of the mounting locations . Therefore, if it is desired to mount mower discs of different diameter e.g. larger diameter on the cutter bar, it is only necessary to increase the spacing apart of the gearboxes (by increasing the space between the mounting locations) and to use longer shafts to couple together adjacent gearboxes . This possibility of easy adaptation of the cutter bar to different mower discs is a considerable technical, and cost saving, advantage over known designs of cutter bars with internally mounted gears. In the known arrangement of cutter bars, major design alteration is necessary to vary the mounting locations of the mower discs and to ensure that the internal gear drive tram (extending internally from one end to the other of the cutter bar) is able to provide drive to the mower discs at different mounting locations. The cuttei bar is made of any suitable load-bearing fabrication to support the mower discs, and in a preferred arrangement cutter bar will be supplied in standard lengths, and will be cut to required length, or joined together to other lengths, depending upon the number of mower discs which are to be mounted thereon. This provides economies of scale in supply, and ease of fabrication according to the number of mower discs to be installed. Preferably, each torque transmitting element comprises a connecting shaft or stub shaft which is releasably connectable at each end to the adjacent housing. Assuming that the drive input to the gear train is at one end of the cutter bar, an output end of each upstream housing (le closer to the drive input end) will be coupled releasably to one end of one of the stub shafts, and an input end of the corresponding downstream housing will be coupled releasably to the opposite end of the shaft . The releasable coupling of each stub shaft to the input and out ends preferably comprises an axially slidable connection, whereby sliding movement in one direction to couple with one of the housing ends can then be followed by axial sliding movement in the opposite direction to couple with the other of the housing ends. Once the coupling to both housings is completed, an axial restraint device may be used to prevent axial movement of the shaft. This may comprise a circlip and circumferential groove arrangement. The cutter bar is preferably a hollow profile which is four sided, having a frontal face, a rear face and top and bottom faces . The bar may be extruded of trapezoidal cross- section, with the frontal face being smaller in height than the rear face, and preferably with the frontal face forming the mounting face for the gearbox housings. In the event of gear wear or damage, it is a simple matter to remove the associated housing (after simple uncoupling of the drive shafts to the adjacent housings), and then a replacement gear and/or housing can readily be installed . Usually, the mower discs will be arranged to be rotated in opposite directions, along the length of the cutter bar, and conveniently this may be achieved by providing a common design of transfer shaft which can be installed in each of the gearbox housings. Each gearbox housing will usually have a crown wheel, rotatable about an upright axis, and which provides rotary drive to a mower disc mounted thereon, and drive rotation to each crown wheel will be derived from a bevel gear mounted on the common design of transfer shaft. In order to provide reverse rotation to successive crown wheels, the transfer shafts are mounted in one or the other of two diametrically opposite positions within each gearbox housing, (each position being in line with the externally mounted stub shaft). The bevel gear on the transfer shaft will then apply rotation m one direction, or an opposite direction, to the crown wheels of successive gearbox housings arranged along the length of the cutter bar. The stub shafts preferably have slidable engagement with the respective ends of the transfer shafts via splined connections . A preferred embodiment of cutter bar for an agricultural disc mower according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a frontal and perspective illustration of part of a cutter bar assembly according to the invention; Figure 2 is a perspective illustration, partly from the rear, with respect to the mowing direction, showing further components of the cutter bar assembly, and in a mowing position; Figure 3 is a view, similar to Figure 2, showing the cutter bar assembly pivoted to an intermediate position between an upright transport position, and the mowing position shown m Figure 2 in which it is extended substantially parallel to the ground over which the mower is travelling; and Figure 4 is a detailed frontal view showing the coupling together of two adjacent gearbox housings mounted on a frontal mounting face of the cutter bar Referring now to the drawings, there is shown a cutter bar and gear tram assembly according to the invention, designated generally by reference 10, and which is intended to be mounted on a frame (not shown) of a multi-disc type mowing machine having a plurality of mower discs (see Figure 2) which are required to be mounted at spaced apart positions along the length of the cutter bar, and to be driven by a gear drive tram associated with the cutter bar. The cutter bar is designated generally by reference 11 , and is preferably a hollow metal extrusion eg of aluminium, which is of generally trapezoidal cross-section, as seen at the right hand end of Figure 1, having a front face 12, a rear face 13, a bottom face 14, and a top face 15. The cutter bar 11 is intended to be mounted on the mowing machine so as to extend generally perpendicular to the mowing direction, shown by arrow X m Figure 2, and generally parallel to the surface of the ground over which the machine is travelling. Usually, the mowing machine will be towed behind an agricultural tractor, or other propelling vehicle, and also derives its power input to operate the mower discs via the PTO shaft of the tractor and a drive train to gears which drive the mower discs. The cutter bar 11 is shown in a mowing position in Figure 2, whereas in Figure 3 it is shown in an intermediate position between the mowing position, and an upright transport position . In known constructions of cutter bar, a gear drive tra to operate the mower discs is mounted internally of the cutter bar. However, as will be described in more detail and as shown in the drawings of the preferred embodiment, the gear drive tram to the mower discs is mounted externally of cutter bar 11. The cutter bar 11 is provided with a number of mower disc mounting locations 16 along its length, and it will be apparent from the drawings that the mounting locations 16 are provided externally of the cutter bar 11 and on the frontal face 12. This is a preferred arrangement, although it should be understood that it is within the scope of the invention for the gear train and associated drive components to be mounted on other external faces of the cutter bar 11 (eg the top face 15), if required. Each mounting location 16 provides a mounting for a respective mower disc, one of which is shown by reference 17 in Figure 1 , and a series of mower discs 17 being shown in Figure 2. Usually, the mower discs 17 are caused to rotate in relatively opposite directions, along the length of the cutter bar. Each mower disc 17 is driven to rotate about an upwardly extending axis, which may be slightly inclined m the mowing direction, and this axis extends also generally perpendicular to the axis of the cutter bar. The axis of rotation is shown schematically by dashed line 18 in Figure 1. A respective gearbox housing 19 is mounted externally of the cutter bar 11 at each mounting location 16, and each housing 19 mounts a respective mower disc 17 thereon so as to be capable of applying driving torque thereto. A drive input to the cutter bar is provided at one end of the cutter bar, and is shown generally by reference 20 in Figure 2. A forwardly extending coupling shaft 21 receives input power from the PTO shaft of the tractor via suitable shaft connection, and rotation of the input shaft coupling 21 is transferred to a transverse shaft 22, universal coupling 23 and then into an upper end of a "cone disc" 24. The cone disc 24 serves to guide the standing crop onto the adjacent mower disc 17a, as it is rotated in a clockwise direction, and the power input to the cone disc 24 comprises the input power to operate all of the mower discs 17 via the externally mounted gear drive tram. The transmission of torque to operate the successive gearbox housings 19 is achieved by providing external torque transmitting elements, and which transmit torque between adjacent pairs of gearbox housings. In the preferred arrangement shown in the drawings, the torque transmitting elements comprise connecting shafts 25, which are releasably connectable at each end to an input end of a transfer shaft provided in each gearbox housing 19 Although not shown, a common design of transfer shaft is mounted inside each gearbox housing 19, and extends generally parallel to the common axis of the connecting shafts 25, but is capable of being mounted in either one of two diametrically opposed positions. The gearbox housing mounts a crown wheel which rotates about the axis 18, so as to provide drive input to the mower disc 17, but successive crown wheels are rotated opposite directions by means of successive reversal of the mounting of the transfer shaft. Thus each transfer shaft has a bevel gear mounted at one end, to engage with the respective crown wheel, but with successive reverse mounting of the transfer shaft, the bevel gear will rotate the crown wheels in successively opposite directions . The transfer shaft mounted inside each gearbox housing has axial sliding interfit with the connecting shaft 25, and preferably this is achieved by splmed interconnections. This provides for simple assembly and disassembly of the connection shaft 25, which can move axially in one direction, and then in an opposite direction, to fit, or to uncouple itself from the inputs and outputs of an adjacent pair of gearbox housings. Any suitable axial restraint device may be provided to lock the connecting shaft 25 in driving positions, and this may comprise circlips and circumferential groove types of arrangement. It will be noted that the cutter bar 11 is a relatively simple and therefore inexpensive fabrication or construction, conveniently being formed as a standard length of extruded section. The standard length can be cut down to size, depending on the number of mower discs which are to be provided on the cutter bar Alternatively, for a very long cutter bar assembly eg for 8 up to 10 mower discs, the standard length may not be long enough, which case it is a simple matter to oin a necessary additional length of cutter bar section. The entire gear drive mechanism, and torque transmission to the gear drives are mounted externally of the cutter bar 11 , and this facilitates assembly, and disassembly. Furthermore, unlike the known internally mounted gear drive mechanisms, assembly and disassembly of the gearboxes in the event of gear wear or damage can easily be carried out, wholly independently of the mounting and demounting of adjacent gearboxes. It will be appreciated that the mounting locations 16 on the cutter bar 11 will be spaced apart from each other by a distance which corresponds to the diameter of the mower discs 17 which are to be provided. The mounting holes on the front face 12 of the cutter bar 11 will therefore be formed at required positions corresponding to the intended locations of the mounting 16, by relatively simple machining operations, and then required lengths of shaft 25 will be selected according to the particular spacing apart of the gearboxes. Evidently, in the event of required use of different diameter mower discs 17, it is a simple matter to choose a different mounting location 16, corresponding to a different spacing apart between adjacent gearboxes, and it is then only necessary to select different lengths of connecting shafts. The gear train components which operate the mower disc can remain the same, so that this does not need to be changed, and the only changes are minor machine-shop work to alter the positions of the mounting locations, plus a selection of different length shafts.

Claims: CLAIMS 1. A cutter bar (10) for a multi-disc mowing machine having a plurality of mower discs (17) which are required to be mounted at spaced apart positions (16) along the length of the cutter bar, and to be driven by a gear drive train associated with the cutter bar, in which: a) the cutter bar (11) is intended to be mounted on the mowing machine so as to extend generally perpendicular to the mowing direction X and generally parallel to the surface of the ground over which the machine is travelling when towed behind a propelling vehicle; b) the cutter bar (11) has an external mounting face (12) which is provided with a number of mower disc mounting locations (16) which are spaced apart along the length of the cutter bar, each location (16) being adapted to provide a mounting for a respective mower disc (17) whereby the latter can be driven to rotate about an upwardly extending axis (18) extending generally perpendicular to the axis of the cutter bar ( ii ) ; c) a respective gearbox housing (19) is mounted externally of the cutter bar (11) at each of said mounting locations (16), each housing (19) being adapted to mount a respective mower disc (17) thereon so as to be capable of applying driving torque thereto; d) torque transmitting elements (25) are located externally of the cutter bar (11) and each arranged to transmit torque between an adjacent pair of gearbox housings (19); and e) a drive input (20) is arranged to receive power input from the propelling vehicle, and to transmit torque to the gearbox housings (19) via the torque transmitting elements (25). 2. A cutter bar according to claim 1, in which each torque transmitting element comprises a connecting shaft (25) which is releasably connectable at each end to the adjacent hous ing ( 1 9 ) . 3. A cutter bar according to claim 2, in which the releasable coupling of each connecting shaft (25) comprises an axially slidable connection. 4. A cutter bar according to claim 3, in which an axial restraint device is provided to prevent axial movement of each connecting shaft (25) when it has been mounted in position . 5. A cutting bar according to any one of claims 1 to 4, in which the cutter bar (10) has a hollow profile which is four sided, having a frontal face (12), a rear face (13), a bottom face (14) and a top face (15). 6. A cutter bar according to claim 5, in which the frontal face (12) forms the mounting face provided with the mounting locations (16) on which the gearbox housings (19) are mounted . 7. A cutter bar according to any one of claims 1 to 6, in which each gearbox housing (19) has a crown wheel mounted therein, rotatable about an upright axis (18) in order to provide rotary drive to a mower disc (17) mounted thereon. 8. A cutter bar according to claim 7, in which a transfer shaft (not shown) is mounted within each gearbox housing (19), and has a bevel gear which is engageable with the crown wheel . 9. A cutter bar according to claim 8, in which the transfer shafts are mounted in one or the other of two diametrically opposite positions within each gearbox housing (19), so that the bevel gear on the transfer shaft can apply required direction of rotation to the respective crown wheel and mower disc (17). 10. An agricultural multi-disc mower incorporating a cutter bar according to any one of the preceding claims.

Inventors: LAURITZEN GEORG, MIKKELSEN SOEREN, LAURITZEN, GEORG, MIKKELSEN, SOEREN
Applicants: KVERNELAND TAARUP AS, LAURITZEN GEORG, MIKKELSEN SOEREN, LAURITZEN, GEORG, MIKKELSEN, SOEREN
Application year: 1998
Main classification: A01D34
IPC codes: A01D34