Three-point power lift of an agricultural tractor

Description

[0001] The invention relates to a three-point linkage of an agricultural tractor with a lower link, comprising a first coupling device arranged at a first lower link end for attaching an attachment interface and a second coupling device arranged at a second lower link end for attaching a tractor-side articulation point of the three-point linkage.

[0002] Such lower links are known, for example, from documents DE 27 49 311 A1, EP 1 111 984 B1 and DE 102 51 234 A1 and are used in a wide variety of designs on three-point linkages of agricultural tractors. Typically, a bearing eye is formed on a lower link end attached to the tractor, in which a bearing ball with a central bore is pivotally mounted. The central bore serves to accommodate an axle stub that protrudes from the front of a support element flanged in the area of ​​a rear axle differential housing. Dismantling the lower link, for example to increase the lateral clearance of a drawbar during transport work with a trailer or the like, is associated with a comparatively high level of effort.

[0003] A three-point linkage according to the preamble of claim 1 is known from document EP 2 870 842 B1. 1

[0004] It is therefore an object of the present invention to further develop a three-point linkage of the type mentioned at the outset with regard to improved handling.

[0005] This problem is solved by a three-point linkage having the features of patent claim 1.

[0006] The three-point linkage of an agricultural tractor with a lower link according to the invention comprises a first coupling device arranged at a first lower link end for attaching an attachment interface and a second coupling device arranged at a second lower link end for attaching a tractor-side articulation point of the three-point linkage. The second coupling device has a coupling body with a catch hook and a locking mechanism, wherein the locking mechanism serves to releasably lock a coupling ball assigned to the tractor-side articulation point within the catch hook.

[0007] This allows for quick and easy removal of the lower link from the three-point linkage.

[0008] Advantageous further developments of the three-point power lift according to the invention of an agricultural tractor with a lower link are evident from subclaims 2 to 8.

[0009] Preferably, the catch hook forms a fastening area provided for the form-fitting reception of the coupling ball, wherein a spring-loaded locking bolt mounted in the coupling body can be deflected obliquely to a defined reception direction of the catch hook such that in the relaxed or unactuated state, a straight locking section arranged on the locking bolt tangentially projects over or overlaps the fastening area at an imaginary apex of a coupling ball to be received. The part of the locking section projecting beyond the apex lies in the way of the coupling ball in the defined reception direction and holds it securely in the catch hook. The relaxed or unactuated state of the locking bolt corresponds to a negligible orrelatively low spring preload, which is dimensioned in such a way that the locking bolt within the coupling body is reliably secured against unwanted vibration-related movements.

[0010] In other words, the catch hook forms a fastening area that complements the coupling ball for a positive fit. The fastening area represents an imaginary outer shell of the coupling ball—except for a certain amount of bearing play required for dirt tolerance. To center the coupling ball, the catch hook has a mouth-shaped receiving area that merges into the actual fastening area. The opening of the catch hook in the fastening area guides the coupling ball along the specified receiving direction.

[0011] Furthermore, it is conceivable for the locking bolt's deflection direction to be at an angle of 20 to 40 degrees relative to the predetermined receiving direction of the catch hook. This angle range is ideal for implementing a snap lock, since when a coupling ball is inserted into the catch hook, the force components acting on the locking bolt are predominantly oriented in its deflection direction or in the direction of the spring preload. This ensures that the locking bolt is pushed away from the coupling ball without jamming.

[0012] As soon as the coupling ball has reached its final position, the locking bolt automatically returns to its initial position, which locks the coupling ball, under the effect of the spring preload.

[0013] A grip piece designed as an extension of the locking bolt may protrude from the underside of the coupling body. This allows the locking bolt to be pulled out of its unclamped state to release the catch hook from the coupling body.

[0014] The locking bolt can have a round cross-section. In this case, a corresponding bore is formed in the coupling body as a sliding fit. To prevent undesired rotation of the locking bolt within the sliding fit, at least one projection can be formed on an outer contour of the locking bolt, which engages in a complementary recess formed along the sliding fit in the deflection direction of the locking bolt.

[0015] In this case, both the locking bolt and the sliding fit can have a stepped cross-section such that opposing stops are formed for a compression spring that applies the spring preload. To assemble the locking mechanism, the compression spring is first placed onto the locking bolt. The resulting assembly is then inserted into the sliding fit on the upper side of the coupling body facing the jaw-shaped receiving area of ​​the catch hook. A fastener is then used to secure it against falling out in the area of ​​the handle protruding from the underside.

[0016] A concave holding section can be connected to the straight locking section for positive engagement with a coupling ball that is accommodated in the fastening area. The concave holding section allows the coupling ball to be clamped within the catch hook in such a way that vibration-induced movements within the catch hook are largely eliminated.

[0017] The three-point linkage of an agricultural tractor with a lower link according to the invention is explained in more detail below with reference to the attached drawings. Identical reference numerals refer to identical or functionally comparable components. They show: Fig. 1 shows an embodiment of the lower link according to the invention, Fig. 2 shows a sectional side view of a coupling device provided on the lower link for locking a coupling ball with a locking mechanism in the locked state, Fig. 3 shows a sectional side view of the coupling device according to Fig. 2 with the locking mechanism in the unlocked state, Fig. 4 a sectional view of the coupling device according to Fig. 2 , Fig. 5 a plan view of a coupling body encompassed by the coupling device according to Fig. 2 with the locking mechanism dismantled, and Fig. 6 an embodiment of a device for use with the lower link according to the invention according to Fig. 1 adapted support element for attachment to an agricultural tractor.

[0018] Fig. 1 shows an embodiment of the lower link according to the invention for a three-point linkage (not shown) of an agricultural tractor.

[0019] The lower link 10, manufactured as a forged and / or welded steel part, comprises a first coupling device 14 arranged at a first lower link end 12 for attaching an attachment interface. The first coupling device 14 is designed as a conventional coupling hook 16 with a manually operated snap lock 18, which serves to receive a coupling ball encompassed by the attachment interface. The snap lock 18 has a spring-loaded locking latch 20, which can be moved into a retracted position to release the coupling hook 16 by manually pulling out an actuating element 22 provided on an upper side of the coupling hook 16. The structure and function of such a coupling hook 16 are well known, so they will not be discussed further here.

[0020] Furthermore, a second coupling device 26 is provided on a second lower link end 24 for attaching a tractor-side pivot point of the three-point power lift. The second coupling device 26 has a coupling body 28 with a catch hook 30 and a Fig. 2 shown in detail locking mechanism 32, which serves for the releasable locking of a coupling ball assigned to the tractor-side articulation point within the catch hook 30.

[0021] As in Fig. 2 As can be seen, the catch hook 30 forms a fastening area 36 provided for the form-fitting reception of an associated coupling ball 34. A spring-loaded locking bolt 38 mounted in the coupling body 28 can be deflected obliquely to a fixed receiving direction 40 of the catch hook 30 such that in the relaxed or unactuated state, a straight locking section 42 arranged on the locking bolt 38 tangentially projects over or overlaps the fastening area 36 at an apex 44 of the coupling ball 34. The part 46 of the straight locking section 42 projecting beyond the apex 44 lies in the way of the coupling ball 34 in the defined receiving direction 40 and holds it securely in the catch hook 30. The relaxed or unactuated state of the locking bolt 38 corresponds to a negligible orrelatively low spring preload, which is dimensioned such that the locking bolt 38 within the coupling body 28 is reliably secured against undesired vibration-induced movements.

[0022] In other words, the catch hook 30 forms a fastening area 36 that is complementary to the coupling ball 34 for the positive-locking reception of the latter. The fastening area 36 represents an image of an imaginary outer shell of the coupling ball 34 - except for a bearing play Δd in the range of 2 to 3 mm that must be provided for reasons of dirt tolerance. To center the coupling ball 34, the catch hook 30 has a mouth-shaped receiving area 48 that merges into the actual fastening area 36. The opening of the catch hook 30 in the fastening area 36 guides the coupling ball 34 along the defined receiving direction 40.

[0023] According to the sectional view of the second coupling device 26 in Fig. 4 Adjoining the straight locking section 42 is a concave holding section 50 for positive engagement with a coupling ball 34 received by the fastening area 36. The concave holding section 50 clamps the coupling ball 34 within the catch hook 30 under the action of the spring preload in such a way that vibration-induced movements within the catch hook 30 are largely excluded.

[0024] According to Fig. 1 Both the coupling hook 16 of the first coupling device 14 and the catch hook 30 of the second coupling device 26 have an upward opening during operation. However, it is also conceivable for the catch hook 30 of the second coupling device 26 to open in the opposite direction. The lower link 10 is then hooked from above into the tractor-side pivot point of the three-point linkage.

[0025] To realize a snap closure, the deflection direction 52 of the locking bolt 38 ideally runs at an angle of 20 to 40 degrees relative to the fixed receiving direction 40 of the catch hook 30, for example at an angle of approximately 30 degrees. Fig. 3 As can be seen, when the coupling ball 34 is inserted into the catch hook 30, force components oriented predominantly in its deflection direction 52 or in the direction of the spring preload act on the locking bolt 38. This ensures that the locking bolt 20 is pushed away from the coupling ball 34 without jamming. As soon as the coupling ball 34 has assumed its final position, the locking bolt 38 automatically returns to its initial position, locking the coupling ball 34, under the effect of the spring preload.

[0026] On the underside of the coupling body 28, a handle 54 protrudes, designed as an extension of the locking bolt 38. This allows the locking bolt 38 to be pulled out of its relaxed state for the purpose of unlocking the catch hook 30 from the coupling body 28 (see Fig. 3 ).

[0027] The locking bolt 38 has a Fig. 5 The coupling body 28 has a corresponding bore formed as a sliding fit 56. To prevent undesired rotation of the locking bolt 38 within the sliding fit 56, opposing projections 60, 62 are formed on an outer contour 58 of the locking bolt 38, which engage in indentations 64, 66 formed complementarily along the sliding fit 56 in the deflection direction 52 of the locking bolt 38.

[0028] Both the locking bolt 38 and the sliding fit 56 have a stepped cross-sectional profile such that opposing stops 68, 70 are formed for a compression spring 72 applying the spring preload (see Fig. 2 ). To assemble the locking mechanism 32, the compression spring 72 is first placed onto the locking bolt 38. The assembly thus formed is then inserted into the sliding fit 56 on the upper side of the coupling body 28 facing the mouth-shaped receiving area 48 of the catch hook 30 and is secured against falling out in the area of ​​the handle 54 emerging on the underside by means of a fastening element 74. The fastening element 74 is a securing split pin 76 inserted through the handle 54, which, when the locking bolt 38 is in the relaxed state, rests on the end face of an extension 78 formed on the coupling body 28.

[0029] Furthermore, a bore 80 is provided in the area of ​​the handle 54, which, when the locking bolt 38 is in the relaxed or unactuated state, is aligned with a counterbore formed in the extension 78. This allows a locking bolt (not shown) to be inserted through it, so that the locking bolt 38 can be mechanically locked.

[0030] Fig. 6 depicts an exemplary embodiment of a support element 80 adapted for use with the lower link 10 according to the invention for attachment to an agricultural tractor. The support element 80, which is to be flanged to a rear axle differential housing of the agricultural tractor, has a central support axle 82, at the front ends 84, 86 of which integrally formed coupling balls 34 are provided for attaching a respective lower link 10 or the catch hook 30 encompassed by the lower link 10.

Claims

1. Three-point power-lift linkage of an agricultural tractor, having a lower link, comprising a first coupling device (14), disposed on a first lower link end (12), for attaching an attachment apparatus interface, and a second coupling device (26), disposed on a second lower link end (24), for attaching an articulation point of the three-point power-lift linkage on the tractor, wherein the second coupling device (26) has a coupling body (28) with a catch hook (30) and a closure mechanism (32), characterized in that a coupling ball (34) assigned to the articulation point of the three-point power-lift linkage on the tractor is releasably locked within the catch hook (30) by means of the closure mechanism (32).

2. Three-point power-lift linkage according to Claim 1, characterized in that the catch hook (30) forms a fastening region (36) provided for receiving the coupling ball (34) in a form-fitting manner, wherein a locking bolt (38) which is mounted so as to be spring preloaded in the coupling body (28) is deflectable obliquely to an established receiving direction (40) of the catch hook (30) in such a manner that, in the non-activated state, a straight blocking portion (42) disposed on the locking bolt (38) protrudes tangentially beyond the fastening region (36) in an imaginary apex (44) of a coupling ball (34) to be received.

3. Three-point power-lift linkage according to Claim 2, characterized in that the deflection direction (52) of the locking bolt (38) runs at an angle of 20 to 40 degrees in relation to the established receiving direction (40) of the catch hook (30).

4. Three-point power-lift linkage according to Claim 2 or 3, characterized in that a gripping piece (54) formed as an extension of the locking bolt (38) projects on a lower side of the coupling body (28).

5. Three-point power-lift linkage according to at least one of Claims 2 to 4, characterized in that the locking bolt (38) has a round cross section.

6. Three-point power-lift linkage according to Claim 5, characterized in that formed as a sliding fit (56) in the coupling body (28) is a bore corresponding to the round cross section, wherein both the locking bolt (38) and the sliding fit (56) have a step-shaped cross-sectional profile in such a manner that opposite stops (68, 70) are formed for a compression spring (72) applying the spring preload.

7. Three-point power-lift linkage according to Claim 6, characterized in that at least one projection (60, 62) is formed on an external contour (58) of the locking bolt (38), which engages in a concavity (64, 66) moulded in a complementary manner along the sliding fit (56) in the deflection direction (52) of the locking bolt (38).

8. Three-point power-lift linkage according to at least one of Claims 2 to 7, characterized in that a concave retaining portion (50) for resting in a form-fitting manner on a coupling ball (34) to be received by the fastening region (36) adjoins the straight blocking portion (42).

9. Carrier element for use with a three-point power-lift linkage according to at least one of the preceding claims, characterized by a central carrier axle (82) on the front ends (84, 86) of which are provided integrally moulded coupling balls (34) for attaching the lower link (10).