Clutch device for a lower link of a three-point power lift

Description

[0001] The invention relates to a coupling device for a lower link of a three-point linkage, comprising a coupling body with a catch hook for receiving a coupling element designed complementarily with a fastening area of ​​the catch hook, wherein a locking mechanism with a housing is arranged on the catch hook, within which a sliding fit for longitudinally displaceable bearing of a locking bolt is designed such that the locking bolt can be deflected against a restoring spring force from a first locking position locking the catch hook into a second locking position releasing the catch hook.

[0002] Such coupling devices are offered by various manufacturers and typically feature a locking mechanism with a locking bolt engaging the catch hook. When a coupling ball, enclosed by an implement interface, is engaged, the locking bolt moves against a restoring spring force into a position that releases the catch hook. Once the coupling ball reaches its end position, the locking bolt snaps back into its original position, simultaneously locking the catch hook. The components of the locking mechanism are housed in a casing located on the top of the catch hook. This casing is designed to be disassembled for maintenance purposes and is therefore complex to manufacture.Document DE 27 49 311 A1 discloses a three-point coupling in which locking elements of catch hooks arranged on the lower links can be jointly operated from the driver's seat via a simple and reliable operating device using traction elements.

[0003] The object of the present invention is to further develop a coupling device of the type mentioned above with regard to simplified manufacturing.

[0004] This problem is solved by a coupling device with the features of claim 1.

[0005] The coupling device for a lower link of a three-point linkage comprises a coupling body with a catch hook for receiving a coupling element designed complementarily to a mounting area of ​​the catch hook, wherein a locking mechanism with a housing is arranged on the catch hook, within which a sliding fit for the longitudinally displaceable bearing of a locking bolt is designed such that the locking bolt can be deflected against a restoring spring force from a first locking position, which locks the catch hook, to a second locking position, which releases the catch hook. According to the invention, the sliding fit is designed as an ovalized inner contour extending along the deflection direction of the locking bolt.

[0006] In this case, the entire housing of the locking mechanism can be a single, integral part of the coupling body, with the sliding fit within it being machined into a forged steel blank in a single operation using CNC milling with correspondingly high precision. This significantly simplifies the manufacturing of the coupling assembly.

[0007] The lower link is a component of a conventional three-point linkage on an agricultural tractor. More precisely, there are left and right lower links, which run symmetrically to each other and are each equipped with a coupling device. The two lower links are mounted to a lower section of the rear differential housing of the agricultural tractor and can be raised and lowered by an operator using a hydraulic lift.

[0008] Advantageous further developments of the coupling device according to the invention are set out in the dependent claims.

[0009] Preferably, bar stock made of rolled or forged steel is used to manufacture the locking bolt, pre-machined with respect to an outer contour corresponding to the inner contour of the sliding fit. The use of pre-machined bar stock allows for cost-effective production of the locking bolt with minimal effort.

[0010] A maintenance opening can be provided on the rear of the housing, facing away from the mounting area of ​​the catch hook. The sliding fit extends into this opening, allowing the locking bolt, along with the other components of the locking mechanism, to be inserted into the housing from the rear and closed using a removable maintenance cover. This results in a particularly compact and robust design for the locking mechanism.

[0011] Furthermore, it is possible that a pull lever is attached to the locking bolt, by means of which the locking bolt can be manually deflected towards the second locking position. For this purpose, the pull lever, or a handle attached to it, extends outwards from the rear of the housing or from an outlet opening formed in the removable maintenance cover.

[0012] The pull lever may be equipped with a locking device that allows the locking bolt to be secured in the second locking position. In its simplest form, this locking device is a recess along the pull lever that engages with an edge of the rear exit opening. This accommodates the fact that the three-point linkage has left and right lower links with their respective coupling devices, and the operator cannot operate the corresponding locking mechanisms simultaneously. The locking device allows the locking bolts of both coupling devices to be moved into the second locking position, making it easier to insert the coupling elements of an implement interface to be attached to the three-point linkage into the catch hooks simultaneously.

[0013] To protect the locking mechanism from damage that can occur when the pull lever is suddenly released while in the deflected position due to the restoring spring force, it is conceivable that an elastic stop element be provided inside the housing to limit longitudinal displacement of the locking bolt towards the first locking position. This elastic stop element could, for example, be an elastomer strip inserted into an internal groove in the housing.

[0014] The pull lever can be fitted with a counter-stop that interacts with the elastic stop element. The restoring spring force acting on the locking bolt presses the counter-stop compressively against the elastic stop element, thus defining the position of the first locking position.

[0015] The counter-stop can be designed as an L-shaped extension on the pull lever.

[0016] Furthermore, the locking bolt may have a concave contact contour facing the mounting area, which corresponds in particular to an outer curvature of a coupling element to be received therein. The latter is especially relevant when the coupling element is a coupling ball. If the coupling ball is in contact with the concave contact contour, the rising flank of the concave contact contour prevents the locking bolt from being pushed onto the coupling ball.

[0017] The concave mounting contour can taper off on a side facing away from a free end of the locking bolt in such a way that it intersects the mounting area, viewed in the direction of deflection of the locking bolt, at a distance smaller than the coupling diameter of the catch hook for a coupling element to be received therein. A coupling element located in the catch hook thus forms a redundant stop for the locking bolt in the direction of the first locking position.

[0018] Furthermore, it is conceivable that, with the release of the mounting area, the locking bolt can be deflected from the first locked position exclusively perpendicular to a receiving direction defined by the opening path of the catch hook in the mounting area, whereby the locking bolt in the first locked position extends beyond the mounting area by more than half in the defined receiving direction, thus blocking it. If a coupling element designed as a coupling ball is located in the mounting area, the locking bolt extends accordingly beyond the apex facing the locking bolt in the receiving direction. This largely eliminates the possibility of the locking bolt being pushed open due to a force exerted by the coupling element. The locking mechanism thus formed therefore renders separate safety measures unnecessary.

[0019] If double-acting hydraulic cylinders are used to operate the hydraulic lifting mechanism encompassed by the three-point linkage, then, due to the aforementioned characteristics of the locking mechanism, it is readily possible to exert a downward force on the ground via the two lower links of a soil cultivation implement attached to them. This is important to note because the locking hooks on the lower links open upwards, meaning that almost the entire applied force is transmitted via the locking bolts or the locking mechanism to the coupling elements of the implement interface.

[0020] The locking bolt may also have a recess to accommodate a spring element that generates the restoring spring force, with the recess communicating with a drainage opening for fluid drainage. The latter may be a housing opening that opens into the sliding fit. This reliably prevents excessive water accumulation in the locking mechanism, thus avoiding corrosion-related damage, particularly to the spring element located in the recess, which is typically a helical compression spring made of steel wire.

[0021] The coupling device according to the invention for a lower link of a three-point linkage is explained in more detail below with reference to the accompanying drawings. Identical reference numerals refer to identical or functionally comparable components. The drawings show: Fig. 1 shows a sectional view of an embodiment of the coupling device according to the invention with a coupling body comprising a catch hook and a locking mechanism for locking a coupling ball received therein; Fig. 2 shows a detailed view of a coupling body with a locking mechanism according to the invention. Fig. 1 the locking bolt with a concave mounting contour, Fig. 3 a sectional view of the in Fig. 2 the depicted locking bolt, Fig. 4 a perspective view of the in Fig. 1 The coupling device shown has a housing of the locking mechanism formed integrally as part of the coupling body, Fig. 5, based on the coupling device according to Fig. 1 The illustrated operating situation, in which a redundant stop for the locking bolt is formed by the coupling ball, and Fig. 6 with the coupling device according to Fig. 3 Equipped lower link for a three-point linkage of an agricultural tractor.

[0022] Fig. 1 shows an embodiment of the coupling device according to the invention.

[0023] The coupling device 10 comprises a coupling body 12 with a catch hook 14 for receiving a coupling element 18 which is complementary to a mounting area 16 of the catch hook 14. The coupling body 12 is welded to an end region 20 of a lower link 22, which is part of a three-point linkage (not shown) of an agricultural tractor. More precisely, the three-point linkage has left and right lower links that run symmetrically to each other and each is connected to the Fig. 1 are equipped with the coupling device 10 shown.

[0024] For example, in the fastening area 16 there is a coupling element 18 designed as a coupling ball 24, which is encompassed by an attachment interface (not shown) of a soil cultivation implement, such as a plow, harrow or seed drill, or of a mounted implement in the form of a fertilizer spreader, a spray boom or the like.

[0025] Furthermore, the coupling device 10 has a locking mechanism 26 with a locking bolt 28. The locking bolt 28 is longitudinally displaceable in a sliding fit 32 formed in a housing 30 of the locking mechanism 26, perpendicular to a receiving direction 34 of the coupling ball 24 defined by the opening path of the catch hook 14 in the mounting area 16. According to the perspective view of the coupling device 10 in Fig. 4 The sliding fit 32 is designed as an ovalized inner contour extending along the deflection direction 36 of the locking bolt 28, which in this case has an A-shaped widened cross-sectional profile. Under the action of a restoring spring force F, the locking bolt 28 is forced into a first locking position 38 that blocks the catch hook 14, so that the coupling ball 24 located in the mounting area 16 is locked in the catch hook 14 (see also Fig. 1 ).

[0026] The catch hook 14 has a jaw-shaped receiving area 40 for centering the coupling ball 24, which then transitions into the actual mounting area 16. The coupling ball 24 is designed to be complementary to the mounting area 16, except for a predetermined bearing clearance Δd. The opening of the catch hook 14 in the mounting area 16 guides the coupling ball 24 along the defined receiving direction 34.

[0027] As in Fig. 1 As can be seen, the locking bolt 28, located in the first locking position 38, projects beyond the mounting area 16 in the defined receiving direction 34 by more than half its length, thus locking it in place. If, as here, a coupling element 18 designed as a coupling ball 24 is located in the mounting area 16, the locking bolt 28 accordingly extends beyond the apex 42 facing the locking bolt 28 in the receiving direction 34.

[0028] A maintenance opening 46 is provided on the rear side of the housing 44, facing away from the mounting area 16 of the catch hook 14, into which the sliding fit 32 extends, so that the locking bolt 28 including the other (described below) components of the locking mechanism 26 can be inserted into the housing 30 from the rear and closed in it by means of a removable maintenance cover 48.

[0029] More precisely, the complete housing 30 is a single-piece component of the coupling body 12, with the sliding fit 32 running within it being machined into a forged steel blank in a single operation with correspondingly high precision by means of CNC milling. The one-piece construction of the coupling body 12 is best illustrated by the following: Fig. 4 The perspective view of the coupling device 10 shown is recognizable.

[0030] To release the coupling ball 24, the locking bolt 28 can be deflected backwards against the restoring spring force F into a second locking position 52, releasing the catch hook 14, by means of a pull lever 50 articulated to the locking bolt 28. For this purpose, the pull lever 50, or a handle 54 formed thereon, extends outwards from the housing 30 or from an outlet opening 56 formed in the removable maintenance cover 48. For articulated mounting, the pull lever 50 has a mounting eye 60 received in a pocket-shaped recess 58 of the locking bolt 28, which is held in place by means of a bearing bore 62, 64 opposite the locking bolt (see [reference to relevant section]). Fig. 2 und 3 ) held bolt 66 rotatably fastened.

[0031] In other words, within the housing 30, the sliding fit 32 for the longitudinally displaceable bearing of the locking bolt 28 is designed such that the locking bolt 28 can be deflected against a restoring spring force F from a first locking position 38 which locks the catch hook 14 into a second locking position 52 which releases the catch hook 14.

[0032] A locking device 68 is formed on the pull lever 50, by means of which the locking bolt 28 can be locked in the second locking position 52. The locking device 68 is a recess 70 formed along the pull lever 50, which can be engaged in an edge 72 of the rear exit opening 56.

[0033] To protect the locking mechanism 26 from damage, an elastic stop element 74 is provided inside the housing 30 to limit longitudinal displacement of the locking bolt 28 towards the first locking position 38. The elastic stop element 74 is, for example, an elastomer strip 78 inserted into an internal housing groove 76.

[0034] Furthermore, a counter-stop 80, in the form of an L-shaped projecting extension 82, is formed on the pull lever 50 and interacts with the elastic stop element 74. The restoring spring force F acting on the locking bolt 28 compresses the counter-stop 80 against the elastic stop element 74, thus defining the position of the first locking position 38. The compressibility of the associated elastomer strip 78 is dimensioned such that it keeps the counter-stop 80 formed on the pull lever 50 out of contact with the adjacent housing section in the first locking position 38. The locking bolt 28 is therefore "floating" in the first locking position 38 under the influence of the restoring spring force F.

[0035] The locking bolt 28 is chamfered at a free end 84 located in the receiving direction 34 such that it is forced into the second locking position 52 when the coupling ball 24 is inserted into the catch hook 14. As soon as the coupling ball 24 has assumed its final position, the locking bolt 28 automatically returns to the first locking position 38 under the action of the restoring spring force F. In this way, a snap lock is implemented, which allows the coupling process with an attachment interface to be carried out particularly conveniently.

[0036] As shown in the sectional view of Fig. 1 As can be seen, the restoring spring force Frücx is generated by means of a spring element 86 in the form of a helical compression spring 88 made of steel wire, which is received at one end 90 in a blind hole 92 formed on the inside of the locking bolt 28 and is supported at a second end 94 on the maintenance cover 48 of the housing 30. A guide rod 96, attached to the maintenance cover 48, runs inside the compression spring 88, ensuring that the compression spring 88 is compressed without kinking when the locking bolt 28 is moved towards the second locking position 52.

[0037] Additionally, a concave contact contour 98 runs along the locking bolt 28, facing the mounting area 16, and corresponds to an outer curvature of the coupling ball 24 located in the mounting area 16. When the coupling ball 24 is in contact with the concave contact contour 98, the rising flank 100 of the concave contact contour 98 blocks the locking bolt 28 from being pushed forward by the coupling ball 24.

[0038] As already mentioned, the coupling ball 24 has a specific bearing clearance Δd within the mounting area 16. This clearance is on the order of 2 to 3 millimeters. This enables a contamination-tolerant "positive fit" between the coupling ball 24 and the locking bolt 28, which ensures trouble-free opening and closing of the locking mechanism 26 even under adverse conditions.

[0039] Fig. 2 shows a detailed view of the locking mechanism 26 according to Fig. 1 The locking bolt 28 was included. On its underside, a drainage opening 104 for fluid drainage can be seen, which, according to the sectional view in Fig. 3 with the recess provided for receiving the compression spring 88 in the form of the blind hole 92 and in the installed state accordingly Fig. 1 in addition, it communicates with an outer housing opening 106 that opens into the sliding fit 32.

[0040] The locking bolt 28 is manufactured using bar stock made of rolled or forged steel, which is pre-machined with respect to an outer contour corresponding to the inner contour of the sliding fit 32. During the manufacturing process, the bar stock is first cut to the appropriate length. Subsequently, the end-face contours and all recesses or bores are machined.

[0041] According to Fig. 2 The concave mounting contour 98 is spherical except for an interruption in the form of a cylindrical section 102, and is thus adapted to the outer curvature of the coupling ball 24. The cylindrical section 102 allows for a certain amount of longitudinal play relative to the coupling ball 24 located in the mounting area 16 with respect to the deflection direction 36 of the locking bolt 28, which accommodates possible fitting tolerances of the coupling ball 24. The width of the cylindrical section 102 is between 3 and 4 mm.

[0042] In Fig. 5 Figure 1 depicts an operating situation in the event of a loss of the rotatable attachment between the locking bolt 28 and the pull lever 50, for example, in the case of a breakage of the bolt 66 or the mounting eye 60. In such a case, the compression spring 88 pushes the locking bolt 28 beyond the first locking position 38 and out of the sliding fit 32. To prevent the locking bolt 28 from falling out, the concave contact contour 98 tapers off on a side 108 facing away from the free end 84 of the locking bolt 28 such that it intersects the mounting area 16, viewed in the deflection direction 36 of the locking bolt 28, at a distance A that is smaller than the coupling diameter D k of the catch hook 14 for the coupling ball 24 to be received or already received therein. The coupling ball 24 located in the catch hook 14 thus forms a redundant stop for the locking bolt 28 in the direction of the first locking position 38.

[0043] In Fig. 6The lower link 22, equipped with the coupling device 10, is shown. It is designed as a 3D-formed forged steel part. A free area 110 allows easy access to the locking mechanism 26 and the pull lever 50 provided for its operation.

[0044] To facilitate operation of the pull lever 50, an actuating ring 112 passes through an eyelet provided on the handle 54. A screwdriver, for example, can be passed through the actuating ring 112, its blade being supported on the lower link 22 and thus used as a lever.

Claims

1. Coupling device for a lower link of a three-point linkage, comprising a coupling body (12) with a catch hook (14) for receiving a coupling element (18) of complementary design to a fastening region (16) of the catch hook (14), wherein disposed on the catch hook (14) is a locking mechanism (26) having a housing (30) within which a sliding fit (32) for mounting a locking latch (28) so as to be longitudinally displaceable is formed in such a manner that the locking latch (28) is able to be deflected, counter to a restoring spring force (Frestore), from a first locking position (38) blocking the catch hook (14) to a second locking position (52) releasing the catch hook (14), characterized in that the sliding fit (32) is formed as an internal contour which is continuously ovalized along the deflection direction (36) of the locking latch (28).

2. Coupling device according to Claim 1, characterized in that for the production of the locking latch (28) of rolled or forged steel existing bar stock is used, which is prefabricated in terms of an external contour so as to correspond to the internal contour of the sliding fit (32).

3. Coupling device according to Claim 1 or 2, characterized in that a service opening (46), into which the sliding fit (32) opens as an extension, is incorporated in a housing rear side (44) facing away from the fastening region (16) of the catch hook (14).

4. Coupling device according to at least one of the preceding claims, characterized in that a pull lever (50) is attached to the locking latch (28), by means of which the locking latch (28) is able to be deflected manually in the direction of the second locking position (52).

5. Coupling device according to Claim 4, characterized in that a latching device (68), by means of which the locking latch (28) can be retained in the second locking position (52), is formed on the pull lever (50).

6. Coupling device according to Claim 4 or 5, characterized in that an elastic stop element (74) for delimiting a longitudinal displacement of the locking latch (28) in the direction of the first locking position (38) is provided within the housing (30).

7. Coupling device according to Claim 6, characterized in that a counterstop (80) which interacts with the elastic stop element (74) is formed on the pull lever (50).

8. Coupling device according to Claim 7, characterized in that a concave contact contour (98), which faces the fastening region (16) and corresponds, in particular, to an outer curvature of a coupling element (18) to be received therein, is formed on the locking latch (28).

9. Coupling device according to Claim 8, characterized in that the concave contact contour (98) on a side (108) facing away from a free end (84) of the locking latch (28) runs out in such a manner that it intersects the fastening region (16) in the deflection direction (36) of the locking latch (28) at a spacing (A) smaller than a coupling diameter (Dk) of the catch hook (14) for a coupling element (18) to be received therein.

10. Coupling device according to at least one of the preceding claims, characterized in that the locking latch (28), while releasing the fastening region (16), is able to be deflected from the first locking position (38) exclusively perpendicularly to a receiving direction (34) defined by the opening course of the catch hook (14) in the fastening region (16), wherein the locking latch (28) when located in the first locking position (38) protrudes in a locking manner beyond the fastening region (16) by more than half in the defined receiving direction (34).

11. Coupling device according to at least one of the preceding claims, characterized in that a recess (92) for receiving a spring element (86) generating the restoring spring force (Frestore) is formed in the locking latch (28), wherein the recess (92) communicates with a drainage opening (104) for discharging liquid.