GB2178935A - A mowing machine - Google Patents

Abstract

A mowing machine comprises a rotary cutting unit (8) mounted on a shaft (37) which is supported in a drive unit (33). The cutting unit (8) comprises a cutter carrier (62) and a cutter (10) which is mounted on the cutter carrier (62) by a fastening member in the form of a bolt (79). The bolt (79) has a supporting boss (80) receiving the cutter (10). The boss (80) is received non-rotatably in a recess (81) of a coupling member (83) disposed below, and fastened by the bolt to the cutter carrier (62). The bolt (79) is secured to the cutter carrier by a nut (85) above the cutter carrier (62). <IMAGE>

Description

1 GB 2 178 935 A 1

SPECIFICATION

A mowing machine This invention relates to a mowing machine, particularly, although not exclusively, for agricultural purposes.

According to the present invention, there is provided a mowing machine comprising at least one cutting unit which is supported in a support so as to be rotatable about a rotary axis, the cutting unit comprising a cutter secured to a cutter carrier by means of a fastening member with respect to which the cutter is freely rotatable, and the fastening member comprising a bolt and a supporting boss for the cutter, the 80 supporting boss being located non-rotatably in a recess below the cutter carrier, the bolt being retained with respect to the cutter carrier by fastening means disposed above the cutter carrier.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure 1 is a plan view of a mowing machine hitched to a tractor; Figure 2 is an enlarged vertical sectional view of a cutting unit of the machine of Figure 1; Figure 3 shows part of Figure 2 on an enlarged scale; and Figure 4 is a plan view of the cutting unit of Figure 2.

As shown in Figure 1, the mowing machine has a hitch 3 which is attached to the three-point lifting device 1 of a tractor 2. An intermediate frame 4 is mounted on the rear of the hitch 3 and is pivotable with respect to the hitch 3 about a substantially horizontal pivot axis 5 extending in the intended direction of travel of the mowing machine, indicated by an arrow A. In the illustrated embodiment the axis 5 is located approximately in the vertical longitudinal central plane of the tractor 2. The intermediate frame 4 extends, during operation, from the axis 5 mainly towards a lateral boundary plane 28 of the tractor 2, parallel to the direction A, and thus extends trans versely of the direction A.

A main frame 6 is mounted on the end of the 110 intermediate frame 4 nearer the side of the tractor 2 for pivotal movement with respect to the intermediate frame 4 about a pivotal axis 7. The axis 7 is parallel to the axis 5 and is a short distance inside the boundary plane 28. Viewed on plan, the main frame 6 is in line with the intermediate frame 4 and therefore also extends transversely of the direction A.

In the embodiment shown in Figure 1, the main frame 6 carries six cutting units 8, which can be driven about upwardly extending rotary axes 9. The rotary axes 9 may be vertical, but preferably, during operation, they are slightly forwardly inclined from bottom to top. Each cutting unit is provided at its circumference with one or more cutters 10 (there are two in the illustrated embodiment). The ends of the cutters 10 of the cutting unit nearest the intermediate frame 4 describe a circle, during operation, which extends close to the boundary plane 28.

The intermediate frame 4 and the main frame 6 are pivotable with respect to the hitch 3 about an 130 upwardly extending axis 11 located at least approximately in the vertical central plane of the tractor 2 and connecting the intermediate frame 4 with the hitch 3. In normal operation, turning about the pivotal shaft 11 is prevented by a known shear bolt mechanism 12, which is disposed away from the vertical central plane of the tractor and connects the intermediate frame 4 with the hitch 3.

Above the main frame 6 there is a framework 13, the periphery of which is provided with flexible walls extending down to the ground for intercepting objects such as stones and the like thrown up by the cutters during operation, so as to retain them inside the flexible hood around the framework 13.

An auxiliary shaft 14 is connected between a power take-off shaft of the tractor 2 and an input shaft 16 of the mower. The shaft 16 is arranged in a sleeve 15 which is rigidly secured to the intermediate frame 4 and extends substantially horizontally in the direction A. The centreline of the input shaft 16 journalled in the sleeve 14 coincides with the axis 5. The input shaft 16 projects from the rear of the sleeve 15, the projecting portion carrying a pulley 17. Near the end of the intermediate frame 4 nearer the main frame 6 there is a pulley 18 which is mounted on a shaft 19. The shaft 19 is journalled on the one hand in lugs 20 and 21 provided on the frame 4 and on the other hand in a gear box 22, which is pivotable with respect to the lugs 20 and 21 and is located between them. The gear box 22 is rigidly secured to the main frame 6. The centreline of the shaft 19 coincides with the axis 7. The pulley 17 is drivably connected with the pulley 18 by at least one V-belt 23, which runs around the two pulleys and is located behind the intermediate frame 4 with respect to the direction A. The shaft 19 of the pulley 18 carries a bevel gear wheel 27, which is in the gear box 22 and meshes with a bevel gear wheel 25 whose rotary axis is approximately horizontal in operation and intersects the axis 7 substantially at right angles. The shaft of the gear wheel 25 is journalled in a substantially vertically extending gear box 26, which is rigidly secured to the gear box 22 and fastened at the lower end to the main frame 6. The shaft of the bevel gear wheel 25 is provided with a gear wheel 27 located inside the gear box 26 and coupled through one or more intermediate gear wheels (not shown) with a gear wheel (not shown) fastened to a main drive shaft 31 journalled in the main frame 6. The main frame 6 fastened to the underside of the gear box 26 is made up of intermediate pieces 32 and drive units 33.

which are alternately arranged and interconnected by a tie rod 34. The intermediate pieces 32 and the drive units 33 are respectively substantially identical to each other. They are cast components which together make up a hollow beam constituting the main frame 6 in which the main drive shaft 31 and the tie rod 34 are accommodated. The tie rod 34 draws the intermediate pieces and drive units towards one another and secures them to the lower end of the gear box 26. The intermediate pieces and drive units together with the tie rod constitute a bending-resistant unit of the main frame beam 6 carrying the cutting units 8 and their drive gear.

Figure 2 shows in detail a vertical sectional view of one of the drive units 33. The section is taken in a 2 GB 2178 935 A 2 plane parallel to the length of the beam 6 and includes the axis 9 of the cutting unit. The drive unit shown is clamped between two intermediate pieces 32. As is shown in Figure 2, the main drive shaft 31 extends through the intermediate pieces and the drive unit. The 70 main drive shaft 31 may have any desired shape so that it can be drivably coupled with a bevel gear wheel 35, which has a bore matching the shape of the drive shaft 31 for rotatably coupling the gear wheel 35 with the main drive shaft 31. In this embodiment the main 75 drive shaft 31 has a square section and is located in a square, uninterrupted hole in the bevel gear wheel 35, which hole fits around the shaft 31. The bevel gear wheel 35 is in mesh with a bevel gear wheel 36, the centre line of which coincides with the axis 9 and intersects the centre line of the bevel gear wheel 35 and the drive shaft 31 at right angles. The gear wheel 36 has an upwardly extending shaft 37 on which the cutting unit 8 is mounted. The shaft 37 has a cylindrical part 38, which is a close fit inside inner races 39 and 40 of a compact bearing 41. The part 38 covers the whole height of the race 39 and part of the height of the race 40. The compact bearing 41 has only one outer race 42, which supports two rows of balls 44 and 45 which fits in a bearing housing constituted by a retaining ring 43. The inner races 39 and 40 are independently movable relatively to each other and bear on the outer race 42 by the rows of balls 44 and 45 respectively. The rows of balls 44 and 45 are arranged in independent cages 46 and 47. The 95 inner race 39 bears at an end face on a supporting shoulder 48 of the bevel gear wheel 36, whereas the outer race 42 bears at its opposite end on a supporting shoulder 49 of the retaining ring 43. The rows of balls 44 and 45 are each located between contact surfaces 100 of the outer race and the respective inner races 39 and which are at an angle 50 which exceeds 0' and is in this embodiment about 30' to a plane normal to the rotary axis 9. The retaining ring 43 is fastened by bolts 51 to the top of a housing 52 of the drive unit 33. The 105 retaining ring 43 is provided with locating recesses 53 for centering the ring 43 with respect to the axis 9. The retaining ring 43 and the housing 52 are castings, and the retaining ring 43 forms a lid on the housing 52.

Above the cylindrical part 38 on the shaft 37 there is 110 a splined part 56, on which a carrying ring 57 is mounted for rotation with the shaft 37. The lower end of the ring 57 is centered on the inner surface of the inner race 40 of the bearing 41. The upper surface 59 of the ring 57 is located above the splined part 56 and 115 provides a projecting boss having a non-circular outer periphery which locates in an opening 61 of a cutter carrier 62.

The cutter carrier 62 is in the form of a strip and is clamped against the carrying ring 57 by a clamping ring 63 and a nut 64 on the shaft 37. The nut 64 is prevented from turning about the shaft 37 by a pin 65.

The cutter carrier 62 mainly constitutes the carrying member of the cutter unit 8 and carries the cutters 10, In the shaft 37 there is a vent channel 70. The vent channel 70 has two parts 71 and 72, which are at an angle to one another of about 90' in this embodiment.

Both of the parts 71 and 72 are inclined to the rotary axis 9. The vent channel 70 extends between the interior of the housing 52 and the splines 56 so that the interior of the housing 52 below the retaining ring 43 is in open communication with the atmosphere. The interior of the housing 52 is otherwise a closed space in which the bevel gear wheels 35 and 36 are accommodated. The interior of the housing 52 is closed by the retaining ring 53, the shaft 37 and the bearing 41. The gaps between the outer race 42 and the inner races 39 and 40 are closed near the ends of the bearing 41 by closing rings 66 provided in the ends of the bearing 41 on opposite sides of the two rows of balls 44 and 45.

The gear wheel 35 is journalled in a bearing 75, the outer race of which is supported in a bore 78 of the cast housing 52. This bore 78 also receives a centering ring 76 which projects beyond the end face of the housing 52 and engages a centering bore which projects beyond the end face of the housing 52 and engages a centering bore of the adjacent intermediate piece 32. Between the bearing 75 and the centering ring 76 there is a retaining ring 77 which engages a groove in the bore 78. A sealing ring, for example an 0-ring, may be provided, if desired between the outer race of the bearing 75 and the bore 78. The gear wheel 35 is integral with a sleeve 35A extending away from the gear wheel towards the other side of the housing 52, where it is journalled in another bearing 75 in the housing corresponding with the bearing 75 adjacent the gear wheel 35. The side of the housing 52 is also centered by a centering ring 76 with respect to the neighbouring intermediate piece 32 and closed towards the hollow space of said intermediate piece by a retaining ring 77. The space inside the housing 52 thus forms a closed space that can be filled with grease or other lubricant for the gear wheels. The continuous opening in the gear wheel 35 and the sleeve 35A, through which extends the shaft 31, does not essentially constitute part of said closed space.

The cutting unit 8 comprises the cutter carrier 62 formed in this embodiment by a strip bent in a plane shown in Figure 2, but it may be formed in a different manner provided that it can carry the cutter 10 and establish a connection between the cutters 10 and the shaft 37. The cutters 10 are connected to the cutter carrier 62, as is shown in Figure 2, by a fastening member formed by a bolt 79. The bolt 79 is arranged near the end of the cutter carrier and has a boss 80 about which the cutter 10 is rotatable. The cutter 10 has an opening 81 in which the boss 80 is located. The top part of the boss 80 is located in a recess 82 of a coupling member 83. The depth of the recess 82 is such that the space between the underside of the coupling member 83 and a head 84 of the bolt 79 is large enough to enable the cutter 10 to rotate freely about the boss 80. The coupling member 83 also has an opening communicating with the recess 82, through which the bolt 79 extends into an opening 90 in the cutter carrier 62, to which the bolt is fastened by a nut 85. The boss 80 is eccentric with respect to the centre line 86 of the bolt 79 so that turning of the boss 80 and the bolt 79 with respect to the cutter carrier 62 and the coupling member 83 is prevented. The nut 85 and the boss 80 clamp the coupling member 83 tightly to the cutter carrier 62. The coupling member 83 has a hub 87 which partly projects above the strip-shaped part of the member 83 and is located in an opening 88 3 GB 2 178 935 A 3 of the cutter carrier 62. The hub 87 is fastened to the cutter carrier by a bolt 94. The hub extends below the rest of the member 83 and this downwardly projecting part forms a stop 89 for the cutter 10. The openings 88 and 90 are spaced apart, but preferably, as in this embodiment, their centre lines are located on a line extending radially of the rotary axis 9.

The cutting unit 8 has a covering hood 93, which is fastened - as is shown in Figure 2 - by the bolts 79 to the cutter carrier 62. the hood 93 is clamped tight between the top surface of the cutter carrier 62 and the nut 85. The hood is also secured to the cutter carrier 62 by the bolts 94, which are screwed into tapped holes in the hubs 87 of the coupling members 83. The covering hood 93 has a curved, central part 95 80 which extends over the nut 64 and the shaft 37. At the periphery of the central part 95 is formed a bead 96 which engages with a close fit around the clamping ring 63. Below the bead 96 the hood has a down wardly diverging conical part which is inclined to the axis 9 by the same angle as the conical parts of the cutter carrier 62 in Figure 2. The hood 93 is formed with protective walls 97 extending around the nut 85 and the top end of the bolt 79 in a manner such that the top end of the bolt 79 does not project above the top of its protective wall 97. Viewed on plan, each protective wall 97 extends through 180' about the axis 86 and then has straight portions extending to the periphery of the hood 93. At the periphery, the hood has a downwardly bent over rim 98, which extends at least as far as a plane going through the underside of the cutter carrier 62. In this embodiment each cutting unit 8 has two diametrically opposite cutters 10. At the circumference between the cutters 10 the hood 93 has upwardly offset portions 99.

For operation, the mowing machine is coupled with the tractor as shown in Figure 1. The cutting units 8 are rotated about their rotary axes 9 by drive trans mitted through the transmission members shown from the auxiliary shaft 14. The shaft 14 drives the main shaft 31 via the V-belt 23 and the gear wheels in the housings 22 and 26. The main shaft 31 extends throughout the length of the main frame 6 and drives each of the shafts 37 in the driving units 33. The direction of rotation of the cutting units about the rotary axis 9 may be chosen by arranging the respective gear wheel 35 on the left- or right-hand side of the rotary axis 9 as viewed in Figure 2. In this way the row of cutting units can be driven in the desired relative directions of rotation.

Each of the cutting units is effectively journalled by its shaft 37 in the drive unit 33 concerned, the bearing 41 constituting a satisfactory support for the shaft 37 in the drive unit 33. The bearings 41 can befitted easily and provide a support over a compartively great 120 height owing to the length of the bearings each having two spaced rows of balls. Nevertheless, the bearings are compact and occupy little space in the drive unit, which can thus be as small as possible. The contact angle of the balls with respect to the recess of about 125 30% the contact angles of the two rows of balls being directed in opposite senses, supports the cutting unit in a manner such that forces exerted thereon from different directions can be satisfactorily absorbed. The cutting unit may be loaded in strongly varying ways, 130 particularly when striking obstacles in unexpected directions. All of these forces can be satisfactorily met by the construction shown of the bearing 41. The separate races 39 and 40 may be advantageous, in particular, because loads resulting from impact with obstacles are usually eccentric with respect to the shaft 37. Since the bearing 41 is an integral unit, it can be readily fitted, and setting errors and the like will practically not occur. Owing to the locations of the contact angles 50 the bearing can absorb both radial and axial forces in both directions. Since fewer errors will be made in mounting the bearing 41 in the drive unit 33, the risk of defects in the drive unit due to such errors is practically nil. Maintenance work on the machine is thus reduced and the minor risk of defects results in a reduced risk of breakdown which could cause fragments of the machine (in particular from high-speed cutting units) to be swept around and ejected, thus exposing the operator or bystanders to serious danger. In particular, cutting units with rotating knives may be dangerous for bystanders when the cutters or other parts are detached as a result of defects. The detached parts may cuase heavy damage, since the cutting members usually turn about their rotary axes at speeds of a few thousand rev/min, for example 3000 to 5000 rev/min.

At these high speeds of rotation of the shafts 37 and the cutting units fastened thereto, thorough lubrication of the components in the driving units 33 is required.

For this reason, the cutting units are constructed so that the drivetransmitting bevel gear wheels are arranged in the closed interior of the housing 52, which is filled with grease or other lubricants. Because heat is generated inside the closed space, it is necessary for there to be communication between this closed space and the open air, and this is why the vent channel 70 is provided in the shaft 37. The parts 71 and 72 of the vent channel 70 are located so that they have a radial component with respect to the axis 9.

Owing to the high speeds with which the shaft 37 is driven, the parts 71 and 72 of the vent channel will remain free of lubricant. The high rotation speed results in such a high centrifugal force on anything in the channel 70 that it will leave the vent channel at one of its ends so that the channel remains free to allow air to excape from the closed space or to enter the closed space from the outside. The closed space communicates through the channel part 71 opening into that space, the channel part 72 and the clearance between the splines 56 with the space above the end surface 59 and through that space with the open air. It is important that the clamping ring 63 and the cutter carrier 62 with the opening 57 should not fit around the part 59 so that this would be hermetically closed.

Although in this embodiment the bearing has two rows of balls, it may, as an alternative, comprise, for example, two rows of rollers.

The hood 93 constitutes a protective cover for the parts located below it and has a shape such that it can deform when heavy forces are exerted on it, for example if unevennesses of the ground are encountered. This deformation will absorb enough of the energy produced by such impact to avoid damage to important parts of the cutting unit and/or other parts. In this embodiment the protective hood 93 is made 4 GB 2178 935 A 4 from thin sheet material, such as metal, of a thickness of, for example, 0.5 mm. However, the protective hood may be made from other material. It may be made from a material such that it can deform to absorb energy and subsequently regain its original shape. The hood may be made from synthetic materials and/or other more or less flexible materials suitable for this purpose.

The hood 93 fully covers the cutter carrier and the fastening areas of the cutters on the cutter carrier so that all important parts are protected by the hood. The walls 97 will sufficiently protect the nuts 85 and the bolts 79 during rotation, and the positions of the bolts 94 behind the walls 97 will avoid damage to them. The higher, central part 95 and the conical part of the hood provide a satisfactory path for delivery of the crop mown by the cutters 10. The walls 97 can also positively contribute to the delivery of the mown crop during rotation of the cutting unit about its rotary axis in the desired direction. Even the upwardly bent-over parts 99 can play a positive part in delivering the mown crop. The parts 99 are bent upwards to provide a free passage for cutters of adjacent cutting units.

The stop 89 of the hub 87 serves to arrest the cutter when it gets below the cutter carrier, for example as a result of impact with an obstacle. The cutter rotatable about the boss 80 can, therefore, not strike the drive housing. The arm 83 forms a satisfactory, readily mounted support for the boss 80 of the cutter.

Although in the embodiment shown in the drawings the axis 9 extends substantially vertically, the construction embodying the invention may also be used with a different position for the axis of the cutting member.

A mowing machine as disclosed herein is also disclosed in our Applications Nos. 8323751 (Serial No. 2126067) and 8531584 (Serial No.

Claims (8)

1. A mowing machine comprising at least one cutting unit which is supported in a support so as to be rotatable about a rotary axis, the cutting unit comprising a cutter secured to a cutter carrier by means of a fastening member with respect to which the cutter is freely rotatable, the fastening member comprising a bolt and a boss which is located non-rotatably in a recess of a coupling member through which the bolt extends, the coupling member being fastened to the carrier by the fastening member, the bolt being retained with respect to the cutter carrier by fastening means disposed above the cutter carrier.

2. A mowing machine as claimed in claim 1, in which a covering hood is fastened to the upper side of the cutter carrier by a further bolt which also secures the coupling member to the cutter carrier.

3. A mowing machine as claimed in claim 2, in which the coupling member is provided with a portion forming a stop for the cutter when it turns to a position below the covering hood.

4. A mowing machine as claimed in claim 2 or 3, in which the fastening member is surrounded at least over part of its periphery by an embossed part of the covering hood which has a height not less than that of the top of the fastening member.

5. A mowing machine as claimed in claim 4, in which the further bolt is located between the embossed part and a conical central part of the covering hood.

6. A mowing machine as claimed in any one of claims 2 to 5, in which a central part of the covering hood extends above a fastening area of the cutter carrier to the shaft of the cutting unit.

7. A mowing machine as claimed in any one of the preceding claims, in which the cutter carrier is mounted on a shaft which is supported in a drive unit forming part of the support for the cutting unit.

8. A mowing machine as claimed in claim 7, in which the drive unit is one of a plurality of drive units which are combined with intermediate pieces to form the support for the cutter unit, the support comprising a main drive shaft drivingly coupled in the drive units with the shafts for the cutter carriers.

Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd, 12186, D8817356. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.