GB1574760A - Hay making machines - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO HAY MAKING MACHINES (71) We, BRITISH LELY LIMITED, of Wootton Bassett, Wiltshire, SN4 7DB, England, a British Limited Liability Company, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to hay making machines.

According to the present invention there is provided a hay making machine comprising a rake member adapted to be driven about an upwardly extending axis of rotation and provided with a group of tines pivotable about a pivot axis into a transport position from an operative position; and retaining means serving to hold the group of tines in the transport position, when the rake member is inoperative, in a manner such that upon operative rotation of the rake member the group of tines automatically becomes free of the retaining means and moves into its operative position, in which position the group of tines is pivotable about said axis free of the effects of the retaining means.

For a better understanding of the invention and to show how the same 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 first form of hay making machine having two drivable rake members Figure 2 is a plan view of part of one of the rake members of Figure 1, in which one of groups of tines as well as its fastening mode, is illustrated, Figure 3 is a plan view of part of one of the rake members of a slightly different form of the rake member as illustrated in Figure 2.

Figure 4 is a side view partly in section taken on the line IV-VI in Figure 2, Figure 5 is a plan view of part of one of the rake members of a second form of hay making machine, one of groups of tines, as well as its fastening mode, being illustrated, Figure 6 is a view taken in the direction of the arrow VI in Figure 5, Figure 7 is a view taken in the direction of the arrow VII in Figure 6, Figure 8 is a plan view of part of the fastening area of one of the groups of tines in a third form of hay making machine, and Figure 9 is a view partly section taken on the line IX-IX in Figure 8.

The hay making machine shown in Figures 1 to 4 has two rake members 1 and 2 which are adapted to rotate in opposite senses about relatively parallel, upwardly and forwardly inclined shafts 3 and 4 respectively (directions A in Figure 1) defining rotational axes for the rake members. The shafts 3 and 4 are fastened to the ends of a horizontal, hollow frame beam 5, which extends transversely of the intended direction B of operative travel of the machine. Near the zone at which the shaft 4 is fastened to the frame beam 5, a gear box is carried on the frame beam 5. This gear box 6 has an input shaft 7 extending in the direction B which can be driven by means of an auxiliarly shaft 8 from a tractor 9 propelling the machine, the rake member 2 thus being driving via the transmission in the gear box 6. By means of the gear box 6 a driving shaft journalled in the frame beam 5 can be actuated to rotate the rake member 1.

At a zone between its ends the frame beam 5 has secured to it a drawbar 10, the foremost end of which can be hitched to the tractor 9.

Each of the two rake members 1 and 2 is supported by ground wheels (not shown).

The dispositions of the axles of these ground wheels is adjustable with respect to the frame beam 5 and fixable in a plurality of positions.

The angle between the frame beam 5 and the drawbar 10 is also variable and fixable at a plurality of values. Viewed in the direction B, the machine can thus be fixed with different relationships to the tractor 9, the angle between the frame beam 5 and the drawbar 10 varying correspondingly and the direction of the ground wheel axles being set accordingly.

The frame beam 5 can be adjusted so that it is an obtuse angle to the direction B. As an alternative the machine can be fastened in known manner to a three-point lifting device of the tractor 9. The drawbar 10 is then replaced by a trestle (not shown), which can be set in different positions, viewed on plan, with respect to the frame beam 5.

To the top end of each shaft 3, 4 is fastened a substantially horizontal, rearwardly extending carrier 11, 12 respectively. These carriers are able to turn-about their associated shafts and can be fixed in a plurality of positions. To the rearmost end of each carrier 11, 12 outside the circumference of the rake member concerned is fastened an upright guide member 13, 14 respectively.

As indicated in Figure 1 by solid lines these guide members are in croptedding positions, whereas as indicated in Figure 1 by broken lines they serve to deposit the displaced crop in the form of a swath, when the rake members rotate in opposite senses.

It is also possible for the rake members to have the same directions of rotation thereby to deposit the crop on one side of the machine in the form of a swath, in which case the frame beam 5 is at an obtuse angle to the direction B.

The hub of each of the rake members 1 and 2 is provided with a plurality of spokes 15 - in the form illustrated four spokes - which are inclined outwardly and downwardly from the hub concerned. The outermost and lowermost ends of all spokes 15 of each rake member 1, 2 are interconnected by an uninterrupted rim 16, which is concentric with the respective shaft 3, 4. The rim 16 of each rake member is provided with a plurality of equally spaced groups of tines 17, in the form illustrated eight groups of tines on each rake member with each group comprising two tines. The paths described by the outermost ends of the tines of both rake members may overlap one another or be contiguous.

In a modified form not illustrated the machine has only one rake member.

Figures 2, 3 and 4 show that in the illustrated machine each group of tines 17 is fastened to a support plate 18 welded to the inner side of the rim 16, preferably near the point at which one of the spokes 15 is fastened to the rim. Each support plate 18 has a flate base 19. the outer edge of which is welded to the inner side of the rim 16 near the top thereof. At the front of the base 19 (Figure 2) or substantially midway the length of support plate 18 (according to the embodiment shown in Figure 3) with respect to the direction of rotation A a cylindrical hollow holder 20 is fastened so that its centre line 21 is substantially parallel to the shaft 3 or 4.

The holder 20 extends from the upper face of the base 19 and accommodates a cylindrical bearing 22, for example, of a synthetic resin, which rotates about the centre line 21 of the holder 20. The bearing 22 has a cross bore 23 at a distance above the upper face of the base 19 in which is received a pivot shaft 24, for which the bearing 22 constitutes a support.

For this purpose the cylindrical holder 20 has a slot, whose direction of length is parallel to the base 19 and which occupies a circumferential angle of about 40". The height of this slot above the upper face of the base 19 is such that when the bearing 22 turns about the centre line 21 the bore 23 invariably registers with the opening of the slot. The centre line of the bore 23 is parallel to the base 19. The base 19 as shown in Figures 2, 3 and 4 is at right angles to the respective shaft 3 or 4, but this base may, as an alternative, extent inwardly and even upwardly away from the rim 16.

With respect to the direction of rotation A, the base 19 has at its rear edge an upright rim 25 at right angles to the base 19 to form a support for the pivot shaft 24. The rim 25 as viewed in plan (Figures 2 and 3) is substantially concentric with the centre line 21 of the holder 20. The rim 25 has two spaced apart circular holes 26 and 27. With respect to the centre line 21 the distance between the two circular holes-26 and 27 equals a circumferential angle of about 30C in the illustrated form. The holes 26 and 27 are located at such a height above the upper face of the base 19 that the pivot shaft 24 inserted into the bore 23 can be passed either into the hole 26 or the hole 27. In turning from one such disposition to the other the pivot shaft 24 moves across the slot in the holder 20, whilst the bearing 22 turns in the holder.

Approximately midway between the holder 20 and the end of the pivot shaft 24 located in the hole 26 or 27 (Figure 2) or near, with respect to the direction of rotation A, the forward end of shaft 24 that is located opposite to the end that is supported by the holes 26 or 27 (Figure 3), pivot axis 21, in this case, being located between these ends.

A holder 28 is welded to the outer side of the pivot shaft 24 and extends upwardly from the pivot shaft 24 in the operational state of the machine. The group of tines 17 comprising two tines 29 and 30 is fastened to the holder 28 by means of a bolt 31. The two tines 29 and 30 have coils 32 and 33 interconnected by an intermediate part which is clamped to the holder 28 by means of the bolt 31. The intermediate part, the coils 32 and 33 and the tines 29 and 30 are made from a single length of resilient steel wire. The tines 29 and 30 extend outwardly away from their coils 32 and 33 in the operational position. The design chosen is such that when the inner end of the tine 29 engages the upper face of the rim 16 the outer free end of this tine is located approximately at ground level. The two tines 29 and 30 are located approximately one above the other in the operational state and have each a free end portion which is sharply bent over downwardly with respect to the adjoining portion in the operational state.

Between the holders 20 and 28 (Figure 2) or alternatively between the holder 20 and the rim 25 (Figure 3) the pivot shaft 24 is surrounded over part of its length by a helical compression spring 34, which engages by its front end, with respect to the direction of rotation A, the holder 20 and which passes diametrically through the pivot shaft 24. In the operational state shown in Figures 2 and 4 by solid lines a pin 35 projects from-the upper side of the pivot shaft 24 and is inclined upwardly and inwardly of the rake member. The centre line of the pin 35 is located, in the operational position indicated by solid lines, approximately in a radial plane passing through the respective shaft 3 or 4. In this position the pin 35 is at an angle of about 45" to the base 19 (Figure 4), this angle opening in the direction towards the shaft 3 or 4 of the rake member 1 or 2. Near the rim 25 the pivot shaft 24 is pierced diametrically by a pin 36 forming part of a retaining mechanism (Figure 2 and 3). This pin 36 also projects, in the operational position, from the top of the pivot shaft 24, in a direction at right angles to the base 19. The force of the spring 34 urges the pin 36 against the upright rim 25 and prevents the pivot shaft 24 from slipping out of the hole 26 in the case of the embodiment according to Figure 2.

The rim 25 is provided with a cam portion 37 forming a further part of the retaining mechanism, which cam portion projects in the direction of the holder 20, viewed with respect to the neighbouring portions of the rim 25. The cam portion 37 is located in the region between the holes 26 and 27 and near the hole 26. At the side adjacent the hole 26 the cam portion 37 has a sloping, projecting cam face 38 terminating in a roughened front face or retaining face 39, which terminates on the side adjacent the hole 27 at an inclined cam face 40. Viewed in a direction tangential of its rim 16 (Figure 4) the cam 37 has a trapezoidal shape, the sides converging in downward direction. In a similar manner a cam portion 41 is provided near the hole 27 on the side remote from the hole 26, this cam portion being located near the hole 27 and having at its side adjacent this hole a sloping, projecting cam face 42 terminating in a front or retaining face 43. The inward boundary of the front face 43 contitutes also a boundary of the rim 25.

When the pivot shaft 24 journalled in the bore 23 is inserted in the hole 26, the spring 34 urging the pin 36 against the rim 25, as viewed in plan, the tines 29 and 30 are orientated radially outwardly or forwardly with respect to the direction of rotation A. This position of the tines is suitable for tedding crop, the guide members 13 and 14 at this time being placed essentially out of operation (position indicated by solid lines for the guide members in Figure 1). When the pivot shaft .24 is withdrawn from the hole 26 against the force of the spring 34 and turned through about 30 so that the rearmost end of the pivot shaft 24, with respect to the direction of rotation A, is located in the hole 27, the tines 29 and 30 occupy the position indicated in Figure 2 by broken lines, in which they point to the rear with respect to the direction of rotation A. This position is suitable for depositing swaths and corresponds with the position of the guide members 13 and 14 shown in Figure 1 by broken lines. In the case of the embodiment of Figure 3, the tips of the tines 29 and 30 are moving outwardly with respect to the corresponding rotational axis 3 or 4 when the tines are turned into the swathing position, due to the particular position of the holder 28 relative to the pivot axis 21.

The centre of gravity of the assembly of the tines 29 and 30, the coils 32 and 33, the intermediate part between the coils, the bolt 31 and the holder 28 is constantly located above the centre line of the pivot shaft 24.

When the rake members 1 and 2 are caused to rotate by the tractor via the auxiliary shaft 8, and provided that the groups of tines are free of their retaining mechanisms - see below, each group of tines 17 of the two rake members can turn, owing to this location of the centre of gravity of the group of tines, under the action of centrifugal force about the centre line of the pivot shaft 24, into the operative position shown in Figure 3 until the lowermost tine 29 engages the rim 16. In the operative position each group of tines is able to pivot about the pivot shaft free of the effects of its associated retaining mechanism.

Thus if the tine 29 touches unevennesses in the ground, the group of tines is able to turn about the centre line of the pivot shaft slightly upwardly in the direction of the arrow C of Figure 3, the group of tines then temporarily floating above the ground. After the unevenness in the ground has been passed by, the group of tines turns immediately in a direction opposite that of the arrow C until the tines 29 re-engages the rim 16. In this operative position and also in the "floating" position the top end of the pin 36 can move along the surface of the rim 25 without the cam portion 37 being touched so that in operation the tines can freely move up and down.

When drive to the rake members 1 and 2 has been stopped, the groups of tines can be tilted up manually in the direction of the arrow C into a non-operative transport position indicated by broken lines in Figure 4 for comparison with the position indicated solid lines in order to reduce the overall working width of the machine or to prevent forwardly extending tines from penetrating into the ground. The tines are turned upwardly over about 90 , but other angles are, of course, also possible. During this motion the top end of pin 36 moves first along the inclined cam face 38 of the cam portion 37 so that the pin 36 and the pivot shaft 24 have to shift in the direction of the holder 20, the spring 34 thus being compressed. If the group of tines is further turned upwardly, the top end of the pin 36 arrives at the front or retaining face 39 of the cam portion 37, the pin 36 being firmly pressed against the face 39 by the increased pressure of the spring 34. This movement is continued until stopped when the end of the pin 35 remote from the pivot 24 touches the upper face of the base 19 (position indicated by broken lines in Figure 4), the pin 35 thus constituting a stop. In this position the retaining mechanism is fully effective and the centre of gravity of the group of tines is located inside the pivot shaft 24, so that the weight of the group contributes to maintaining the group in the transport position. The stop constituted by the pin 35 prevents the group of tines from moving in the wrong direction, in which the tines could be prevented from again reaching the operative position. In the case of the embodiment according to Figure 3 a similar stop could be provided. In the stopped position the pin 36 is about parallel to the base 19, since viewed from the side (Figure 4) and with respect to the direction of the arrow C, the pin 35 leads the pin 36 by an angle of about 45".

The stiffness of the spring 34 and the roughness of the face 39 are chosen so that, when the rake members 1 and 2 are again rotated, the centrifugal force exerted on each group of tines 17 and the fastening area thereof is sufficiently high to cause the pin 36 to move in a direction opposite the direction of the arrow C along the front face 39, after which the pin 36 again moves along the inclined cam face 38 into the position shown in Figure 2, which corresponds with the working position of the tines. In the working or operative position the groups of tines are thus free of the retaining mechanism, and can pivot as already discussed. During the movement along the inclined cam face 38, the spring 34 produced an acceleration in the outward movement of the tines.

From the above it will be appreciated that the groups of tines automatically become free of the retaining mechanisms and turn into the working position when the rake members are rotated.

When the rearmost end of the pivotal shaft 24 with respect to the direction of rotation A is passed through the hole 27, the operation of the inclined cam face 24 and of the front face 43 of the cam portion 41 is completely similar to that of the inclined rim 38 and the front face 39 of the cam portion 37. In the transport position, in which the tines 29 and 30 are approximately parallel to their rotary shafts 3, 4, the engagement between the end of the pin 35 with the base plate 19 prevents the end of the pin 36 from moving behind the innermost rim of the cam portion 41 and from being caught.

In this manner a simple adjustment of the groups of tines into the transport position is achieved, the tines automatically turning into the operative position, when the rake members are again rotated. It is possible to provide only one or two groups of tines of each rake member with the locking device, the group(s) of tines so provided being then located on the outer side of the machine for transport and/or being located at the front of the rake member, if there is a risk of the tines penetrating into the ground, In Figure 5 to 7, which show a second form, corresponding parts are designated by the same reference numerals as in Figures 1 to 4. In this form the front end of the pivot shaft 24 with respect to the direction of rotation A is supported in a holder 44 of different shape as compared with the holder 20. The holder 44, like the holder 20, is rigidly secured to the base 19 and has two upright walls 45 and 46 which form parts of a cylindrical tube whose longitudinal centre line 47 is at right angles to the plane of the base 19. In the plan view of Figure 5 the front and rear parts of the tube are spaced apart so that the wall portions 45 and 46 are spaced apart. The bases of the portions 45,46 are welded to the base 19 and at the top the portions are interconnected by a cover 48 which is parallel to the base 19. The front and rear sides of the holder 44 with respect to the direction of rotation A are bounded, viewed on plan, by two parallel planes 49 and 50 which are approximately normal to the bisector of the angle between the lines of connection between the centre line 47 and the centres of the holes 26 and 27, the holder 44 being open at these planes as viewed substantially tangentially of the rake member. The holder 44 accommodates a bearing 51 forming a support for the pivot shaft 24. Two outer faces of this bearing are formed by parts of a cylindrical surface and are in contact with the inner faces of the wall portions 45 and 46 of the holder 44. The bearing 51 has a bore 52 located at the same level above the base 19 as the holes 26 and 27 with the pivot shaft 24 passed thorough it. At the front of the bearing 51 a pin 53 is diametrically passed through the pivot shaft 24, this pin engaging the front of the bearing owing to the pressure of the spring 34 on the pin 35 and forming part of the retaining mechanism. The pin 36 of the first form, as well as the cam portions 37 and 41 are omitted. On the front of the bearing 51, for example of a synthetic resin, with respect to the direction of rotation A, a cam 54 is provided in the shape shown in Figures 5 to 7, forming a further part of the retaining mechanism. Viewed tangentially of the rake member the cam 54 is arranged symmetrically with respect to the centre line 47 and has a butterfly-shaped design. Each half of the cam 54 located on one or other side of the centre line 47 covers a circumferential angle of about 90 , as shown in Figure 6 about the centre line of the pivot shaft 24. The two boundary lines of each part of the cam 54 facing the centre line 47 is, in fact, a boundary line, from where the cam to one side or the other is arcuate to the front out of the flat front face of the bearing 51 with respect to the direction of rotation A (Figure 7). The foremost part of the cam on each side has a comparatively small cavity 55 bounded by part of a cylindrical surface, whose centre line is parallel to the base 19 and normal to the centre line of the pivot shaft 24. The pin 53 projects on either side of the pivot shaft 24 over a length approximately equal to the width of each of the two halves of the cam 54.

The radius of the cavity 55 may be equal to the radius of the pin 53, but it may have a different value. The two parts of the cam 54 are rigidly secured to the bearing 51 and may be made together with the bearing from a single piece of material.

The position of the tines for tedding the crop and depositing a swath is the same as in the first form, the change-over taking place by moving forwardly the pin 24, against the pressure of the spring 34, with respect to the direction of rotation A, so that the pivot shaft 24 leaves the hole 26 and can be turned about the centre line 47 until the spring 34 presses this shaft into the hole 27 for attaining the position appropriate for depositing a swath. During this change-over the bearing 51 fastened to the pivot shaft 25 in the holder 44 also turns around the centre line 47, since its cylindrical outer faces are in engagement with the inner faces of the cylindrical wall portions 45 and 46. In the operative position the pin 53 is at right angles to the base 19 (Figure 6) so that the two ends of the pin 53 projecting out of the pivot shaft 24 can move along the front face of the bearing 51, when the tine 29 moves across unevennesses of the ground, without these ends coming into contact with the two halves of the cam 54, when the lower tine 29 floats above the ground for a short time.

If the tines have to be turned into the non-operative transport position, the groups of tines are turned upwardly manually in the direction of the arrow C (Figure 4). During this turn the two ends of the pin 53 come into contact with the forwardly arcuate parts of the cam 54 with respect to the direction of rotation A, the transition between the front face of the bearing 51 and the cam parts 54 taking place gradually. If this turn is continued, the ends of the pin 53, after an angular turn through 90 , will snap, for example, into the cavity 55. During the movement of the ends of the pin 53 along the cam the spring 34 is compressed so that the ends of the pin 53 are forced into the cavities 55, whilst the centre of gravity of the group of tines is again inside the pivot shaft 24. The rigidity of the spring 34 and the depth of the cavities 55 are chosen so that, when the rake members are again rotated, the ends of the pin 53 are moved out of the cavities 55 for return at an accelerated rate along the arcuate portions of the cam 54 to the position shown in Figure 6 or adjacent positions so that at the beginning of the operation the groups of tines automatically return to the operative position. It should be noted that the cam 54 is employed both in the tedding position and in the swath-forming position, since the cam 54 is fixed in place with respect to the pivot shaft 24 during the turning about the centre line 47. It is furthermore to be noted that the cavities 55 also constitute a stop for presenting an undesirable movement in the inward direction.

The third form shown in Figure 8 and 9 is mainly based on the construction of the first form (Figures 2, 3 and 4), the holder 20, the bearing 22 and the pin 35 being maintained, but the cam portions 37 and 41 being omitted. The pin 36 is replaced, as shown in Figures 8 and 9, by a plate-shaped support 56 arranged, in the working position, on the top of the pivot shaft 24, this support being parallel to a plane at right angles to the centre line of the pivot shaft 24 and being provided with a holder 57 accommodating a spring, which tends to press a ball 58 forming part of a retaining mechanism in a direction opposite the direction of rotation A. The ball 58 is located, in the working position and the associated tine positions, in which the tines are floating above the ground due to unevennesses, in an elongated cavity 59 (Figure 9) in the rim 25. The cavity 59 occupies part of a circle (for example 30 ), and forms a further part of the retaining mechanism, the centre lying on the centre line of the hole 26 or 27 respectively. One end of the cavity 59, where the ball 58 is located when the tine 29 is in engagement with the rim 16, is located perpendicularly above the centre line of the hole 26. From this one end of the cavity 59 a circular hemispherical cavity 60 covers a circumferential angle of, for example, 90" and also forms part of the retaining mechanism, the centre being located at the same distance from the centre line of the hole 26 or 27 respectively as the curved longitudinal centre line of the elongated cavity 59.

Since in operation the ball 58 bears in the elongated cavity 59, the group of tines 17 can move out of the position in which the tine 19 is in engagement with the rim 16 through an angle of, for example, about 30 up and down without the group of tines being hindered by its fastening structure. The centrifugal force will invariably tend to press the tine 29 to the rim 16. If during standstill of the rake members the groups of tines have to be changed over to a transport position, each group of tines 17 is turned through an angle of, for example, 90" in the direction of the arrow C, the ball 58 emerging from the inner end of the elongated cavity 59 and running along the surface of the rim 25 so that the spring 34 is compressed until the ball 58 snaps into the circular cavity 60, which forms a stop to prevent a further inward movement.

The centre of gravity of the group of tines is then located inside the pivot shaft 24. The cavity forms an adequate retaining means during transport. The depth of the cavity 60 and the tension of the spring are chosen so that, when the groups of tines are again rotated, the centrifugal force exerted on the group of tines and its fastening structure is so high that the ball 58 can emerge from the cavity 60, after which the ball 58 subsequent to some rotation drops into the elongated cavity 59, so that the operative position will be occupied at an increased rate. The cavities 59 and 60 are provided on the corresponding sides of the hole 27 in the rim 25. The ball 58 invariably absorbs the pressure of the compression spring 34.

In the machines described above the groups of tines can, subsequent to passing by unevennesses of the ground, return without delay (caused for example, by the effect of springs tending to turn the tines upwardly) into the operative position, whilst nevertheless a simple and stable retaining mode in the non-operative transport position can be employed..

WHAT WE CLAIM IS: 1. A hay making machine comprising a rake member adapted to be driven about an upwardly extending axis of rotation and provided with a group of tines pivotable about a pivot axis into a transport position from an operative position; and retaining means serving to hold the group of tines in the transport position, when the rake member is inoperative, in a manner such that upon operative rotation of the rake member the group of tines automatically becomes free of the retaining means and moves into its operative position, in which position the group of tines is pivotable about said axis free of the effects of the retaining means.

2. A hay making machine as claimed in claim 1, wherein the pivot axis is defined by a shaft that is subjected to axial spring pressure and that effectively connects the retaining means with the group(s) of tines in the transport position.

3. A hay making machine as

Claims (30)

**WARNING** start of CLMS field may overlap end of DESC **. being located at the same distance from the centre line of the hole 26 or 27 respectively as the curved longitudinal centre line of the elongated cavity 59. Since in operation the ball 58 bears in the elongated cavity 59, the group of tines 17 can move out of the position in which the tine 19 is in engagement with the rim 16 through an angle of, for example, about 30 up and down without the group of tines being hindered by its fastening structure. The centrifugal force will invariably tend to press the tine 29 to the rim 16. If during standstill of the rake members the groups of tines have to be changed over to a transport position, each group of tines 17 is turned through an angle of, for example, 90" in the direction of the arrow C, the ball 58 emerging from the inner end of the elongated cavity 59 and running along the surface of the rim 25 so that the spring 34 is compressed until the ball 58 snaps into the circular cavity 60, which forms a stop to prevent a further inward movement. The centre of gravity of the group of tines is then located inside the pivot shaft 24. The cavity forms an adequate retaining means during transport. The depth of the cavity 60 and the tension of the spring are chosen so that, when the groups of tines are again rotated, the centrifugal force exerted on the group of tines and its fastening structure is so high that the ball 58 can emerge from the cavity 60, after which the ball 58 subsequent to some rotation drops into the elongated cavity 59, so that the operative position will be occupied at an increased rate. The cavities 59 and 60 are provided on the corresponding sides of the hole 27 in the rim 25. The ball 58 invariably absorbs the pressure of the compression spring 34. In the machines described above the groups of tines can, subsequent to passing by unevennesses of the ground, return without delay (caused for example, by the effect of springs tending to turn the tines upwardly) into the operative position, whilst nevertheless a simple and stable retaining mode in the non-operative transport position can be employed.. WHAT WE CLAIM IS:

1. A hay making machine comprising a rake member adapted to be driven about an upwardly extending axis of rotation and provided with a group of tines pivotable about a pivot axis into a transport position from an operative position; and retaining means serving to hold the group of tines in the transport position, when the rake member is inoperative, in a manner such that upon operative rotation of the rake member the group of tines automatically becomes free of the retaining means and moves into its operative position, in which position the group of tines is pivotable about said axis free of the effects of the retaining means.

2. A hay making machine as claimed in claim 1, wherein the pivot axis is defined by a shaft that is subjected to axial spring pressure and that effectively connects the retaining means with the group(s) of tines in the transport position.

3. A hay making machine as claimed in claim 2, wherein the spring pressure is arranged to increase as retaining is effected.

4. A hay making machine as claimed in any one of claims 1 to 3, wherein said pivot shaft is arranged to move lengthwise with respect to the centre line of said shaft when said tine group is turned into the transport position.

5. A hay making machine as claimed in claims 2, 3 or 4, wherein part of the retaining means is arranged on the pivot shaft.

6. A hay making machine as claimed in claim 5, wherein a further part of the retaining means is arranged on a support for the pivot shaft.

7. A hay making machine as claimed in claim 6, wherein said support is rigidly fastened with respect to a hub of the rake member.

8. A hay making machine as claimed in claim 6, wherein said support together with the pivot shaft is movable.

9. A hay making machine as claimed in claim 8, wherein in operation the support is movable with respect to the pivot shaft.

10. A hay making machine as claimed in any one of claims 2 to 9, wherein the orientation of the pivot shaft with respect to the rake member is adjustable to be in any of a plurality of positions.

11. A hay making machine as claimed in claim 10, wherein with a change of said orientation of the pivot shaft the retaining means moves together with the pivot shaft.

12. A hay making machine as claimed in any one of claims 2 to 11 wherein the retaining means comprises a pin arranged on the pivot shaft, this pin engaging, in operation, by spring pressure, a supporting surface forming a support for the pivot shaft.

13. A hay making machine as claimed in claim 12, wherein the retaining means comprises at least one cam on a supporting sur ace.

14. A hay making machine as claimed in claim 13, wherein the cam has a sloping, projecting face orientated towards the pin.

15. A hay making machine as claimed in claim 14, wherein a retaining surface joins the side of the projecting cam face remote from the pivot shaft.

16. A hay making machine as claimed in claim 15, wherein in the transport position of the group of tines the pin is in contact with the retaining surface.

17. A hay making machine as claimed in claim 14, 15 or 16, wherein said projecting surface is orientated so that the spring pres

sure increases when the pin is moved along this surface towards the retaining surface.

18. A hay making machine as claimed in claim 15, 16 or 17, wherein the dimensions and the spring pressure are such that, when the rake member is driven, the pin moves from the retaining surface along the projecting surface towards the supporting surface.

19. A hay making machine as claimed in any one of the preceding claims, wherein a stop is provided, which prevents the group of tines from moving further inwardly when the group of tines is in the transport position.

20. A hay making machine as claimed in claim 19 as appendant directly or indirectly to claim 2, wherein said stop absorbs the spring pressure.

21. A hay making machine as claimed in any one of the preceding claims, wherein the weight of the group of tines contributes to the stability of the transport position of the group of tines.

22. A hay making machine as claimed in claim 11, or in any one of claims 12 to 21 as appendant directly or indirectly to claim 11, wherein the retaining means is located on both sides of the pivot shaft.

23. A hay making machine as claimed in claim 22, as appendant directly or indirectly to claim 13, wherein the retaining surface of the cam has a cavity for receiving the pin in the transport position of the group of tines.

24. A hay making machine as claimed in any one of claims 2 to 7 or 9 to 11, wherein the retaining means comprises a springloaded ball fastened to the pivot shaft.

25. A hay making machine as claimed in claim 24, wherein the ball co-operates with at least one cavity provided in the support.

26. A hay making machine as claimed in claim 25, wherein the cavity has an elongated shape and forms a curvature about the centre line of the pivot shaft.

27. A hay making machine as claimed in claim 25 or 26, wherein a second, hemispherical cavity is provided, in which part of the ball is adapted to fit.

28. A hay making machine as claimed in claim 26 or 26 and 27, wherein the elongated cavity corresponds to the operative position of the group of tines.

29. A hay making machine as claimed in claim 27 or 28, wherein the second cavity corresponds to the transport position of the group of tines.

30. A hay making machine substantially as hereinbefore described with reference to Figures 1 to 4, or Figures 5 to 7, or Figures 8 and 9 of the accompanying drawings.