GB2064290A - Automatic lifting device for an agricultural device, in particular a mower - Google Patents

Abstract

Automatic implement-lifting device lifts the implement (for example, a mower) which is mounted on a vehicle (for example, an agricultural tractor) when said implement strikes an obstacle. A carrier for said device is provided and said device comprises an implement carrier. The implement carrier is so mounted as to pivot about a horizontal axis when the implement strikes the obstacle sufficiently hardly. The device includes a lifting device which raises the implement. The lifting device may be a tension spring 49 or a hydraulic ram. <IMAGE>

Description

SPECIFICATION Automatic lifting device for an agricultural device, in particular a mower This invention relates to an automatic lifting device for an agricultural implement, in particular a mower.

Such an implement may be connected to a tractor via a linkage mechanism which, in the event that the implement strikes against an obstacle, allows the implement to be pivoted relatively to a carrier which is arranged on the tractor. In order to provide protection against harmful effects in the event of agricultural implements unintentionally striking solid objects, it is known in connection with mowers to use devices which (as a result of the impact) remove the mower from the obstacle in a pivoting motion contrary to the direction of travel. Some devices functioning in this manner consist of two rods which can be extended parallel to one another, which run in fishplates and which, by virture of mutual coupling by means of claw-like cams with the coupling point loaded by a spring, maintain the mower in the operating position offset to one side at the rear of the tractor.Should the mower strike against a stone or another solid object, the rod which is connected to the mower is drawn out of the coupling device so that the mower frees itself from the obstacle by a backwards pivoting motion.

However, devices of this kind are effective only when the mower is attached offset to one side at the rear of the tractor because a backwards pivoting motion is only possible from this position. At the same time, this device offers only a small range of pivoting so that, immediately having noticed the impact, the tractor driver must stop the vehicle in order to prevent the next impact. This device also only allows the pivot motion to take place in an approximately horizontal plane; therefore, hitherto, damage to the mowers and to their attaching devices and to the tractor could be avoided only insufficiently. For this reason, the mowers and the attaching devices are provided with greater loadbearing components at the structural design stage.

The principal aim of the present invention is to provide a lifting device of the type in question which allows the implement which is arranged offset to one side at the rear or the front of the tractor to be lifted out of its operating position in such manner as to avoid an impact which would give rise to damage.

In accordance with the present invention, this aim is realised by the implement being attached to an implement carrier which can be pivoted about a horizontal axis relative to a device carrier and by the implement carrier being assigned a lifting device by which the implement is lifted from the ground.

This structural desigh of the lifting device reliably avoids damage to the implement in the event of impact with an obstacle because the carrier is in this case pivoted by the lifting device about a horizontal axis relative to the traction engine and the implement is raised from the ground. This mode of functioning of the lifting device allows the implement to be arranged both at the tail end and at the front end of the tractor.

Expedient further developments of the invention are described in the sub-Claims.

The present invention will now be more particularly described with reference to the accompanying drawings which illustrate a few exemplary embodiments of the invention and in which: Figure lisa side view of a first embodiment of an automatic lifting device with a mower attached; Figure 2 is an enlarged cross-section along the line Il-Il in Figure 1; Figure 3 is a view similar to Figure 1, but with the mower lifted; Figure 4 is an enlarged cross-section along the line IV-IV in Figure 3; Figure 5 is a side view of a second embodiment of a lifting device with a mower attached; Figure 6 is a view in the direction of the arrow VI in Figure 5, Figure 7 is a side view of a third embodiment of a lifting device with a mower attached; Figure 8 is a side view of a fourth embodiment of a lifting device with a mower attached; and Figure 9 is a side view of a fifth embodiment of a lifting device with a mower attached.

A lifting device which is illustrated in Figure 1 and which in toto is indicated by the reference numeral 11 is connected via a carrier 12 to a tractor (not shown). The carrier 12 possesses at least two hinge or attachment points to the tractor and can be raised and lowered at its front end by means of hydraulic cylinders. At the front end of the carrier 12, which consists of two longerons 13, there is attached a coupling device 14 which serves to accommodate or support the lifting device 11. Thus, the drawing shows only one half of the lifting device which, considered in the direction of travel, consists of two identical components. At the upper end of the lifting device, which consists of a vertical carrier 15, said lifting device is rigidly connected by an adjustable spindle (not shown) to a tie-bar 16 of the carrier.At the lower end of the vertical carrier 15, a guide strut 17 with a fishplate 18 is arranged so asto be pivotable about a horizontal axis 51. The guide strut is provided with a guide track 25 which accommodates a displaceable rod 19.

This rod 19 is connected to a mower 20 which slides along on the ground. In the illustrated exemplary embodiment, the mower is equipped with dishlike rotors 21 on the periphery of which are arranged cutting members 22. The rotors 21 are driven by means of toothed wheel gears which are contained in the sandwich-like mower cutting bar 23. In order to improve its sliding characteristics, the mower is provided with an additional landing skid 24. Finger mowers can of course also be attached to the lifting device.

In the transverse direction, the coulisse-shaped guide track 25 and the rod 19 are traversed by a pin 26 which is secured to the rear wall 27 of the guide strut 17. The rod19 acquires its displaceability by virtue of a slot 28 therein which is parallel to the guide track 25. The said slot does not, however, perform a guide function for the rod 19. On the open side of the guide strut 17, a spring-loaded locking plate 29 contacts the rod 19. The compression force is produced by a compression spring 30 which acts between the respective opposite faces or surfaces of the locking plate 29 and of an adjustable nut 34 (see Figure 2) which is screwed onto the free end of the pin 26 provided with a thread.On its side facing towards the rod 19, the locking plate 29 includes at one end a support strip 31 (Figure 4) and at the other end a locking cam 32 which, when the mower is engaged in a cutting operation, slots into a groove 33 formed in the rod 19. In order to enable the rod 19 to be unlocked, it is of significance that sufficient play exists between a through-bore 35 for the pin 26 and the pin itself so that, in the event that the rod 19 is subjected to a sudden force, the locking plate 29 can lift up from said rod.

In front of a rounded end 36 of the rod 19 (see Figures 1 and 3), on the flank-like longitudinal sides 37,38 the guide strut 17 is provided with recesses or cut-away parts which are such that a clamping or gripping lever 39, of which one end is articulated to the vertical carrier 15, can move within them. At its free end the lever 39 is provided with a triangular extension 40 but it must be emphasised that the triangular shape could also be replaced by another shape; however, it must also be emphasized that the included angle formed between that side 50 of the extension 40 which faces the rod 19 and the longitudinal axis of the gripping lever 39, should be kept within specific limits so as to assure the locking function of the lever 39. The junction 41 between the extension 40 and the lever 39 is rounded.

Moreover, in its central zone, the lever 39 possesses in one edge thereof a notch 42 into which engages a claw 43 attached to the guide strut 17. The two angularly movable levers 39 are linked via a torsion shaft 44 and are mounted in the vertical carrier 15. At the rear end, the guide strut 17 is provided with a support clip 45 for a traction cable 46 which is conducted round a cable pulley 48 which is mounted on the vertical carrier 15 by means of a support 47 so as to be freely rotating. On the opposite side, the vertical carrier 15 is attached to one end of a tension spring 49 whose other end is connected to the front end of the rod 19, said spring 49 being tensioned by the weight of the unit.

The mode of operation of the lifting device will now be explained making reference to Figures 1 to 4.

As shown in Figure 1,the mower 20 rests on the ground in the operating position, i.e. with the rod 19 occupying its front position in which the locking cam 32 of the locking plate 29 is engaged in the groove 33 in the rod 19. The claw 43 on the guide strut 17 is engaged in the notch 42 and maintains the lifting device 11 in the operating position with the traction force produced by the traction spring 49 (Figure 1).

At the same time, the lifting device is rigidly secured via the carrier 12 to the tractor at the front andlortail end, as described in the aforegoing.

If, during its operation, the mower should strike or encounter an obstacle, as a result of the impact on the rod 19 (the force of the impact acting lengthways of said rod) the locking plate 29 is raised out of the groove 33. As a result, the rod 19 is moved backwards (i.e. to the right as viewed in Figure 1) so that the lever 39 is positively detached from the claw 43 by the end 36 of said rod 19 contacting the lever 39 at the junction 41 with some force. Immediately thereafter, the spring 49 becomes effective and draws the mower 20 up the rod 19 until the extension 40 of the gripping lever 39 reaches the longitudinal sides 37, 38 of the guide strut 17.

As a result of the lifting of the mower 20, the rod 19 has been returned to its original position, i.e. the locking plate 29 is again biased and its locking cam 32 reoccupies the groove 33. This return motion was effected by means of the extension 40 of the gripping lever 39 and its triangular formation, and the rebiasing function is fulfilled by the bearing side 50 which determines the angle a. Figure 3 illustrates the mower in the lifted state thereof in which the rod 19 has already reassumed its starting position. Until now the procedure takes place automatically.The tractor driver now merely has to pull the cable 46 from the driver's seat position as a result of which the mower 20 is moved downwardly towards the ground (i.e. in an anti-clockwise direction about the pivot axis 51, as seen in Figure 3) so that the claw 43 can re-engage the notch 42 on the gripping lever 39, whereby the Figure 1 position is reached again.

Naturally, this manual procedure can also be effected by a motor drive.

Figure 5 illustrates a second embodiment of a lifting device 11 which is identical in function to the embodiment described above. The structural differences will be explained in the following.

The implement again consists of a mower 20 which is connected to a rod 19 assigned to the lifting device 11. This rod executes a sliding movement in a guide strut 17 and is maintained in function by means of a locking device illustrated in Figures 1 to 4. The guide strut 17 is attached by a fishplate 18 to the vertical carrier 15 so as to be pivotal about a horizontal axis 51. The entire lifting device 11, togetherwith the mower, is supported by the carrier 12. When the release procedure has taken place, which is as yet to be described, a tension spring 49 acts to lift the mower. This spring 49 is secured with bias to the vertical carrier 15 and the rod 19. At its front end the guide strut 17 is provided with a guide arrangement which is designed to be short on the upper longitudinal side 37 but longer on the lower longitudinal side 38.The original cross-section of the guide strut 17 corresponds to a coulisse-like carrier profile. At the front and rear ends of the guide strut 17, bearing blocks 61 are in each case attached to the upper longitudinal side 37 and said blocks have freely rotatable cable pulleys 62 which serve to guide a traction cable 46 of which one end is attached to the rear end of the rod 19. Between the front and rear bearing blocks 61 the upper longitudinal side 37 of the guide strut 17 possesses a narrow recess or access aperture through which the cable 46 can be introduced into the guide arrangement. The traction cable 46 which is looped around the cable pulleys 62 is placed around a cable pulley 48, which is arranged on the vertical carrier 15, and extends to the tractor driver. The gripping lever 39 which is mounted by means of the torsion shaft 44 in the vertical carrier 15 possesses a notch 42 which, during mowing, rests on the wedge-shaped support 64 formed by a recess or interruption 63 in the upper longitudinal side 37.

The lower longitudinal side 38 likewise has a recess or interruption 65 so that the gripping lever 39 can extend through the guide strut 17. The lengths of the interruptions 63, 65 are governed by the length of movement needed to move the gripping lever 39 out of engagement with the support 64. Again in this embodiment it should be ensured that the lifting device 11 consists of two identical components arranged beside one another in the direction of motion, as illustrated in Figure 6.

The lifting device 11 is triggered as a result of impact when the mower abuts against an obstruction, whereby the locking plate 29 is raised from the rod 19. The rod then moves backwards and moves the gripping lever 39 from the support 64 whereby the mower 20 is drawn upwards, by the force of the spring 49, until the gripping lever 39 comes into contact with a rear stop means 66 of the recesses 63 and/or 65 so that when the guide strut 17 is in the oblique position the rod 19 is moved forwards back into its starting position. After these movements have taken place, by means of the cable 46 the driver can bring the mower to the ground as a result of the gripping lever 39 engaging in the wedge-shaped support 64.

Figure 7 illustrates a third embodiment of the lifting device 11 which differs in respect of its mechanism and the associated components from the previously described embodiments.

A disc mower 20 is connected to the lifting device 11 which is attached to the tractor. The connecting element consists of a longitudinal carrier 71 which is mounted on a pivotal deflecting rod 72 so as to be pivotal about a horizontal axis 93. The deflecting rod 72 is itself pivotal about a horizontal axis 94 in the vertical carrier 15 which is rigidly connected to the device carrier 12 and possesses a coupling device 14 for the lifting device 11. The deflecting rod 92 is secured in the vertical carrier 15 in such manner that it can be released by a release safety mechanism 73 which is located in the vertical carrier 15 directly adjoining the upper end of the deflecting rod 72.It consists of a sphere 75 which is loaded by a compression spring 74 and which is pressed into a hollow 77 matched to the respective spherical or partspherical shape at the upper end side 76 of the deflecting rod 72. The sphere 75 is provided with an annular collar 78 on which one end of the compression spring 74 rests.

The release safety mechanism 73 is adjustably attached to the vertical carrier 15; that is to say, the force exerted by the sphere can be modified by means of an adjusting screw 79 which can be locked by means of the nut 80.

At the rear end the longitudinal carrier 71 is provided with a support 81 which contains the mounting of the gripping rod 92. This gripping rod is of telescopic construction or form and can extend in the event of tractional stress. It consists of a fork-like carrier element 82 which is pivotally mounted at its lower end in the support 81 and at the upper end possesses a compression plate 83. Against the compression plate there abuts a compression spring 84 through whose convolutions extends a telescopic rod 85 which is provided at its lower end with a gripping element 86 which abuts externally against the compression spring 84 transversely of its longitudinal axis.A cantilever support arm 87 attached to the vertical carrier 15 possesses a stop strip 88 which is arranged at right angles to the rest of said arm 87 and which engages a so-called suspension cam 89 of the gripping rod 92, said suspension cam 89 being provided on the upper end of the rod 85 and abutting the stop strip 88 during mowing. From the upper end of the rod 85, a traction cable 46 leads across a guide roller 90 which is supported on the deflecting rod 72.

The cable 46 terminates at the driver's seat position.

In order to achieve an improved cable arrangement, a follower member 91 is provided which is connected to the deflecting rod 72 and which possesses a roller or a sliding element. At the front end of the longitudinal carrier 71 there is arranged a tension spring 49 whose second attachment point is to the vertical carrier 15. The spring 49, which exerts its maximum tension force during mowing operation, maintains the device in equilibrium.

If the mower 20 now strikes against a solid object, as a result of the reaction force the deflecting rod 72 is brought out of the release safety mechanism 73 via the longitudinal carrier 71. For this purpose, the carrier element 82 must be telescopic because, when the deflecting rod 72 is inclined forwards, the distance between the stop strip 88 on the vertical carrier 15 and the bearing on the support 81 increases. During this release procedure, the suspension cam 89 of the telescopic rod 85 is pushed by the follower element 91 from the stop strip 88 as a result of which the spring 49 relaxes whilst the mower is raised.

With the aid of the cable 46, the deflecting rod 72 then engages the release safety mechanism 73 whereupon the telescopic rod 85 is positioned upon the support 87.

A fourth embodiment of a lifting device is illustrated in Figure 8. The implement used is a mower 20 corresponding to the previous examples which is attached by means of two lateral carriers 101 and two adjustable spacing means 102 to the carrier 103 of a mobile machine of which only one wheel 104 is shown. The carriers 101 are mounted on the device carriers 103 which each comprise a short pivot arm 105 and a long pivot arm 106. One end of the carrier 101 is articulated to the short pivot arm 105 by means of a horizontal pin or spindle 99. The long pivot arm 106 is attached to a fork-like support 107 into which there is inserted a rod 108 which extends through a slot 109 which is formed in the carrier 101 and which extends longitudinally of said carrier 101.

In order that the mower may be maintained in a stable position, it is provided with lateral flanges 110 which are connected to the tie-bars 100 of the device carrier 103 by means of the spacing means 102.

As soon as the mower 20 is subjected to a sudden force, the impact is transmitted to the carrier 101 and is thereby transmitted to the arm 105. The resultant torque influences, albeit to a reduced extent, the arm 106 in that the latter is lifted and the mower is conveyed out of the impact area. The lowering of the mower is effected by means of a hydraulic operating cylinder (not shown, which acts upon the device carrier 103.

Figure 9 illustrates a fifth embodiment of a lifting device which is provided in particularfora drum mower 111. On account of the construction of this mower, an engine frame 113 thereof which is arranged above the drums 112 requires a device carrier construction which differs from that employed in disc mowers. A device carrier 114 (not shown completely) is permanently connected to the tractor so as to be capable of being raised and lowered. At the tip of the carrier 115 it possesses a fork-like coupling device 14 in which the lifting device, provided with the mower, is attached on one side. A further sup port element, which is not shown in the drawing, connects the upper end of a vertical carrier 115 and the device carrier 114 in adjustable fashion.Deflecting frames 116 which are screwed to the engine frame 113 and which each consists of a thrust arm 117 and a deflecting rod 118, are mounted atthe lower end of the vertical carriers 115 so as to be pivotal about a horizontal axis 124. At the upper end, the deflecting rods 118 are provided with release safety mechanisms 73 which are arranged on the vertical carrier 115 so as to be adjustable and lockable. From the deflecting rod 118 a control lever 120 (which is connected to the control element of a directional control valve 119) projects approximately horizontally and contrary to the direction of deflection. The deflecting rods 118 of the deflecting frames 116 are attached to return cables 121 which possess a quite specific length and are connected to the machine.The pipelines 122 and 123 which are connected to the valve 119 lead to the lifting ram of the device carrier and to the tank or reservoir containing the fluid pressure medium. As in the previous exemplary embodiments the two lateral deflecting frames 116 are linked to one another in a rotary connection.

The simple mode of functioning of the device consists in that the mower 111, having come up against an obstruction, directly brings about the deflection of the deflecting frames 116; as a result of and simultaneously with said deflection, the valve 119 is switched over and the device carrier 114 is lifted hydraulically. The highest lifting point of the lifting device and the lengths of the cables 121 are adapted to one another in such a way that the deflecting arms 118 are withdrawn into the release safety mechanism 73; in this position, the valve 119 changes its state and the drum mower 111 can be lowered again.

In contrast to the drawing, the release safety mechanism 73 could also be arranged so asto operate upwards in a vertical or near-vertical direction.

This would necessitate an additional deflection of the cable 121 to the front side of the device.

It goes without saying that, in any of the lifting devices in accordance with the invention, a detachable joint is provided between the mower on the one hand and the lifting device on the other hand so that a lifting device can be used for different types of implements.

Claims (17)

1. Automatic implement-lifting device connected via a linkage mechanism to a tractor which, when the implement strikes against an obstacle, allows the implement to be pivoted relatively to a device carrier which is arranged on the tractor, wherein an implement is attached to a carrier therefor which can be pivoted about a horizontal axis relatively to the device carrier and wherein the implement carrier is assigned a lifting device which is such as to ensure thatthe implement is raised from the ground when the implement strikes said obstacle.

2. Device as claimed in Claim 1, wherein the carrier consists of an approximately horizontally arranged guide strut and a rod which can be displaced in the guide strut, the implement being attached to the front end of the rod considered in the direction of movement of the tractor the guide strut being pivotal about a horizontal axis relatively to a vertical carrier of the device carrier, and the vertical carrier being articulated to a gripping leverwhich can be brought into locking engagement with the guide strut; wherein the lifting device is formed by a tension spring which acts between the front end of the rod and the vertical carrier an automatically releasable blocking device being provided which, in the event of a predetermined axial load on the rod being exceeded, allows the latterto become displaced relatively to the guide strut, said rod as a result of such axial displacement coming to rest against the gripping lever in orderto negate the blocking engagement of gripping lever and guide strut.

3. Device as claimed in Claim 2, wherein the gripping lever possesses a notch which is in blocking engagement with a projection arranged on the guide strut, and wherein, in the event of an axial displacement of said rod, the rod makes contact with and pushes the gripping lever aside in orderto breakthe engagement of said notch with the projection of the guide strut.

4. Device as claimed in Claim 2 or Claim 3, wherein the blocking device consists of a locking plate which is arranged on the guide strut and which is loaded by the force of a spring against the rod in order to maintain a locking cam of the locking plate in engagement with a groove on the rod.

5. Device as claimed in Claim 4, wherein, at the free end thereof, the gripping lever is provided with an extension which possesses a control area (edge) which, when the guide strut is pivoted about the horizontal axis in the implement-lifting direction, comes to bearagainstthe rear end of the unlocked rod and pushesthe latterforwards so that it re- engages in locking fashion with the locking plate.

6. Device as claimed in any one of Claims 2 to 5, wherein a traction cable leading to the driver's seat of the tractor is connected to the rear end of the guide strut, said cable when pulled causing the guide strut to be pivoted against the force of said tension spring and to be brought again into blocking engagement with the gripping lever.

7. Device as claimed in Claim 1, wherein the implement carrier consists of an approximately horizontal longitudinal carrier and an approximately vertical deflecting rod which is connected to said longitudinal carrier so as to be pivotal about said horizontal axis, the implement being attached to the front end of the longitudinal carrier considered in the direction of motion of the tractor, and the deflecting rod being mounted for pivoting movements about another horizontal axis relative to the vertical carrier of the device carrier; the end of the longitudinal carrier remote from said front end thereof being articulated to a telescopic gripping rod which is provided with a suspension cam which can be brought into engagement with a support arm which is arranged on the vertical carrier above said other horizontal axis; the lifting device being formed by a tension spring which acts between said front end of the longitudinal carrier and the vertical strut, an automatically triggerable released safety mechanism being provided which, in the event of a predetermined axial load on the longitudinal carrier being exceeded, allows the deflecting rod to be pivoted about said other horizontal axis relatively to the vertical carrier, the suspension cam disengaging from the support arm in the event of the deflecting rod pivoting as aforesaid.

8. Device as claimed in Claim 7, wherein the release safety mechanism consists of a sphere which is acted upon by the force of a compression spring, resting on the vertical carrier, and which is forced thereby into a hollow which is arranged atthe upper end of the deflecting rod.

9. Device as claimed in Claim 8, wherein a traction cable which leads to the driver's seat of the tractor acts upon the free end of the gripping rod and, when pulled, causes the longitudinal carrier to be pivoted against the force of said tension spring and allows the suspension cam of the gripping rod to be brought into engagement again with the support arm of the vertical carrier.

10. Device as claimed in Claim 1, wherein the device carrier is a bell crank lever which can be pivoted about another horizontal axis relative to the tractor and which possesses one arm pointing upwards and the other arm pointing forwards the implement carrier being articulated to the free end of the upwards-pointing arm so as to be pivotal about said first-mentioned horizontal axis, the forwardspointing arm engaging under the implement carrier.

11. Device as claimed in Claim 10, wherein a fork-like support is arranged on the free end of the forwards-pointing arm and bears a transverse rod which extends through an elongate slot which is formed in the implement carrier.

12. Device as claimed in Claim 10 or Claim 11, wherein the forwards-pointing arm of the device carrier is longer than the upwards pointing arm thereof.

13. Device as claimed in Claim 1, wherein the implement carrier consists of an angle lever which can be pivoted about said horizontal axis relatively to a vertical carrier of the device carrier and which possesses a forwards-pointing arm and an upwards-pointing arm, the implement being arranged at the free end of the forwards-pointing arm, the upwards-pointing arm engaging with a release safety mechanism arranged on the vertical carrier, one arm of the implement carrier having arranged thereon a control lever which actuates a valve which controls a hydraulic lifting device which acts upon the device carrier.

14. Device as claimed in Claim 13, wherein the release safety mechanism consists of a sphere which is acted upon by the force of a compression spring, resting on the vertical carrier, and which is forced thereby into a hollow which is arranged atthe free end of the upwards-pointing arm of the implement carrier.

15. Device as claimed in Claim 14, wherein a cable is attached to the upwards-pointing arm of the implement carrier and to the tractor, the length of said cable being matched to the highest lifting position of the device carrier in such mannerthatthe upwards-pointing arm of the implement carrier reengages with the release safety mechanism and the control lever switches overthe valve in orderto cause the device carrierto be lowered.

16. Automatic implement-lifting device constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 or Figures 5 and 6 or Figure 7 or Figure 8 or Figure 9 of the accompanying diagrammatic drawings.

17. Any features of novelty, taken singly or in combination, of the embodiments of the invention hereinbefore described with reference to the accompanying diagrammatic drawings.