GB2235359A

GB2235359A - coupling hook

Info

Publication number: GB2235359A
Application number: GB9018599A
Authority: GB
Inventors: Hans-Juergen Langen; Paul Herchenbach
Original assignee: GKN Walterscheid GmbH
Current assignee: Walterscheid GmbH
Priority date: 1989-08-30
Filing date: 1990-08-24
Publication date: 1991-03-06
Anticipated expiration: 2010-08-24
Also published as: IT9021218A1; IT1246424B; GB2235359B; FR2651183A1; DE3928699C2; DE3928699A1; FR2651183B1; IT9021218A0; GB9018599D0

Abstract

In a coupling hook (25) for an attaching device, especially for the lower steering arms of a three-point coupling device of an agricultural tractor, having a hook member (17) and locking means (1, 2) for receiving and locking a bearing ball (18) of a coupling device, the locking elements (1, 2) are in a locking housing (13) welded to the hook member (17) and may take the form of a locking element (1) pivotable around a pin (4) and a spring-loaded releasing leaver (2) for releasing and securing the locking clement (1). <IMAGE>

Description

1 PD/89033GB1 COUPLING HOOK This invention relates to a coupling hook for

an attaching device, especially for the lower steering arms of a three-point coupling device of an agricultural tractor or the like.

Such a coupling, as it is known from West German Patent Specification No. 28 56 971 for example, serves to permit easy and automatic accommodation and locking of a coupling device to an agricultural tractor. For securing the safety catch whose purpose it is to prevent unintentional uncoupling, there is provided a multitude of jointed levers which are associated in a certain way and which have to be attached to the hook member. This kind of assembly is relatively expensive. In addition, because of the relatively rough working conditions, these locking means are subject to high wear which may lead to a relatively large play.

It is the object of the present invention to provide a coupling hook which is easy to produce, has locking means which is protected, and is characterised by a minimum play in respect of the connection between the bearing ball and locking element and which cannot be opened by forces exerted by the bearing ball received in the bearing cup.

The invention provides a coupling hook for an attaching device, especially for the lower steering arms of a three-point coupling device of an agricultural tractor or the like, the coupling hook comprising a hook member and locking means for receiving and locking a bearing ball of an implement to be coupled, the locking 2 means comprising a locking element pivotable around a pin, and a spring- loaded releasing lever for releasing and securing the locking element, wherein the locking means is arranged in a locking housing and the locking housing is welded to the hook member.

The invention permits the locking housing containing the locking means to be produced and fitted separately, whereas the hook member subjected to high loads may, as usual, be produced as a forging. These two parts, after having been produced separately, may be welded together quite easily.

According to a further embodiment, a locking system is to be produced which ensures automatic closing after the coupling operation, which permits opening without any jamming and which, furthermore, has a play-offsetting effect.

The design of these locking means is such that the releasing lever forming part of the locking means is provided with a triangular hole, the locking element is provided with a pin, the locking element is connected to the releasing lever by means of this pin which is movable in the triangular hole, the locking element, at its underside contour, comprises a grooved edge by means of which it may be made to contact a first pin fixed in the locking housing, and the releasing lever, at its end facing away from the locking element, comprises a grooved edge which may be made to contact a further pin fixed in the locking housing, wherein the releasing lever, upon contact with said further pin, holds the edge of the locking element in contact with the first pin with minimum clearance.

c t 3 These measures provide locking means which may be opened by hand or by remote control via a rope, which, during the coupling process, permit automatic opening and closing and which, in the closed position, ensure safety locking with minimum clearance.

To make the locking element pivotable with simple means, it is proposed that, in an oblong hole, it is guided and pivotable around a pin connected to the locking housing.

To avoid unintentional pivoting of the locking element, the locking element may be fixed in the oblong hole by a securing pin insertable into a bore of the locking housing.

To be able to open the locking means by hand and hold it in readiness for the next operation of coupling an attaching device to the coupling hook, it is proposed that the releasing lever may be raised, with the pin of the locking element contacting the lower, rear contact region in the triangular hole and with the grooved edge of the releasing lever being positioned above the pin.

In order to hold the coupling hook in a so-called kick-down position allowing quick and easy uncoupling, it is proposed that the wedge-shaped part of the releasing lever, in the region of its point, should be provided with a step and that the step may establish an operative connection with the pin of the housing, with the pin of the locking element contacting the lower, front contact region of the triangular hole.

An illustrative embodiment of the invention is shown in the accompanying drawings.

4 In the drawings:

Figure 1 shows part of the rear view of an agricultural tractor, comprising coupling hooks attached to lower steering arms; Figure 2 shows a coupling hook for a lower steering arm according to Figure 1, partly in section, comprising a forged hook member and a locking housing accommodating locking means, in a locked condition; Figure 3 shows the locking means of a coupling hook according to Figure 2 in an open conditioon in which it may be operated by hand; Figure 4 illustrates the locking means according to Figure 2 in the process of being opened during the coupling operation; Figure 5 shows the locking means according to Figure 2, comprising a locking element held in the open position, as well as a releasing lever held in readiness, in the so-called kick-down position; and Figure 6 shows a locking housing connected to a hook member and containing the locking means shown in Figures 2 to 5.

As can be seen in Figure 1, today's agricultural tractors, at their rears, are provided with lower steering arms 24 whose free ends comprise coupling hooks 25 which serve to receive attaching devices which are not illustrated. The lower steering arms 24 are stabilised by side stabilisors 23. The tractor is also provided with an upper steering arm 26 providing, with the lower steering arms 24, a three-point coupling device.

As illustrated in Figure 2, a coupling hook 25, in accordance with the invention, comprises an actual hook member 17 and locking means received in a locking housing 13, with the hook member and the locking housing being connected to each other by welds 34. The locking means arranged in the locking housing 13 takes the form of a locking element 1 pivotable about a pin 4, and a releasing lever 2 for releasing and securing the locking element 1. The lever 2 holds the element 1 in a locking position and is spring-loaded by a spring 6, in this case a helical compression spring. The locking element 1 is eccentrically rotatable mounted on the pin 4 which is fixed in the locking housing 13. A slightly curved oblong hole 3 in the locking element 1 in an upper region of the element 1 which is built-in to the housing 13 contains the pin 4. On its underside, the locking element 1 comprises an underside contour 19 which, with a grooved edge 21, may be made to contact a first pin 5 fixed in the locking housing 13. The releasing lever 2 extends only partially into the locking housing 13. At this free end positioned in the locking housing 13, the releasing lever 2 is provided with a wedge part 27 which comprises a grooved edge 10 at the end facing away from the locking element 1. With this edge 10, which provides a step in the region of the point of the wedge part 27, the releasing lever 2 may be made to establish an operative connection with a further pin 8 fixed in the locking housing 13. The releasing lever 2, upon contact with the further pin 8, holds the edge 21 of the locking element 1 in contact with the first pin 5 with minimum clearance.

The locking element 1 is provided with a locking 6 nose 31 which, at a force introduction point 12 thereof, extends into the region of a coupling bed 35 of the hook member 17 facing away from the locking nose 31, the locking element 1 is provided with a pin 9 which is movable in a triangular hole 7 provided in the part 27 of the releasing lever 2. The locking element 1 is, thus, positively interlocked with the releasing lever 2 by the pin 9 which is displaceable in the triangular hole 7.

The triangular hole 7 of the releasing lever 2 comprises an upper contact region 28, a lower rear contact region 29-and a lower front contact region 30. In the locking position as illustrated in Figure 2, the pin 9 is positioned against the upper contact region 28, with the edge 10 of the releasing lever 2 being positioned below the pin 8. The releasing lever 2 is pressed downwards by the spring 6 so that the upper contact region 28, via the pin 9, presses on to the edge 21 and thus against the pin 5. The locking element 1, with its locking nose 31, secures the bearing ball 18 of an attaching device (not illustrated) in the coupling bed 35.

For opening the locking means by hand, the releasing lever 2 is raised against the force of the spring 6, with the pin 9 of the locking element 1 moving in the triangular hole 7 into the lower rear contact region 29. In the process, the edge 10 is released from the pin 8 and the pin 9 of the locking element 1 may escape into the lower front contact region 30. The front contour 11 of the locking nose 31 of the locking element 1 is designed in such a way that between it and the bearing ball 18 there occurs an increasing gap 22 during the opening process. As a result, the locking element 1 may escape inwardly into the locking housing 13, whereby the 7 minimum clearance locking by the wedge part 27 of the releasing lever 2 at the bolt 8 is eliminated.

To ensure that the locking means cannot be opened by unintentionally operating the releasing lever 2, the locking housing 13 is provided with a bore 20 through which a securing pin, which is not illustrated, may be inserted. The securing pin prevents the locking element 1 from escaping into the locking housing 13; in this way, the locking means are secured and cannot be unlocked 10 before the securing pin is removed.

While the locking system is automatically opened during the coupling process, the locking element 1 is tilted around the pin 5 due to force being introduced by the bearing ball on to the locking member 1 in a force introduction point 12 of the locking nose 31. In the process, the locking element 1, with its oblong hole 3, moves along the pin 4 and comes to rest against the rear oblong hole edge 32.

As shown in Figure 4, the releasing lever 2 is raised by the pin 9 in the upper contact region 28 of the triangular hole 7, with the edge 10 being moved into a position above the pin 8; the locking effect is thus eliminated.

In this position, the releasing process commences by moving back the locking element 1 by turning it around the pin 4, with the contour 19 of the underside of the locking element being positioned in such a way that immediately after the first opening movement, there is no longer any contact between the edge 21 and the pin 5.

Undefined friction forces during the opening process are thus avoided.

8 When the bearing ball 18 is introduced into the ball bed 35 of the hook member 17, the force of the spring 6 acting. on the releasing lever 2 ensures that the locking element 1 is pressed downwards via the pin 9. In the process, the locking element 1, with its oblong hole 3, rotates around the pin 4 until the locking position is re-established and until the releasing lever 2, with its edge 10, is positioned with minimum clearance behind the pin 8 of the locking housing 13. The movements of the locking element-1 occurring in the process take place at fixed rotational points around the pins 4 and 5 so that uncontrolled friction processes are avoided. When the closed position has been reached, automatic locking is effected by inserting the edge 10 of the releasing lever 2 behind the pin 8.

As is particularly obvious from Figure 6, the locking housing 13, at its underside, is provided with a large aperture 14 through which any dirt which may have penetrated may fall out freely. The aperture 16 for the releasing lever 2 may be sealed by a flexible sealing element because the angular changes of the releasing lever 2 during the opening process are very slight.

As illustrated in Figure 5, the locking means in accordance with the invention are provided with an integrated so-called kick-down position where the releasing lever 2, with its step 15, rests in the region of the front free end of the wedge- shaped part 27 on the pin 8. The spring 6 is tensioned and the locking element 1, with its pin 9, is positioned in the lower front contact region 30. The underside contour 19 of the locking element 1 is free from the pin 5 and the pin 4 contacts the front edge 33 of the oblong hole 3. After the bearing ball 18 has engaged the hook member 17 of the 4i 9 coupling hook 25, the releasing lever 2, with its step 15, may be pulled off the pin 8 by being hit backwards or by pulling a rope. As a result of the force of the spring 6 the locking element 1 with the oblong hole 3 is tilted around the pin 4 when the pin 9 comes to rest against the upper contact region 28 of the oblong hole 7 of the releasing lever 2. The locking nose 31 leaves the locking housing 13 and reaches the region of the coupling bed 35. The edge 21 contacts the pin 5 and the edge 10 of the releasing lever 2 reaches the locking position behind the pin 8, as illustrated in Figure 2.

Claims

A coupling hook for an attaching device, especially for the lower steering arms of a three-point coupling device of an agricultural tractor or the like, the coupling hook comprising a hook member and locking means for receiving and locking a bearing ball of an implement to be coupled, the locking means comprising a locking element pivotable around a pin, and a spring-loaded releasing lever for releasing and securing the locking element, wherein the locking means is arranged in a locking housing and the locking housing is welded to the hook member.

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2. A coupling hook according to Claim 1, wherein the releasing lever forming part of the locking means is provided with a triangular hole, the locking element is provided with a pin, the locking element is connected to the releasing lever by means of this pin which is movable in the triangular hole, the locking element, at its underside contour, comprises a grooved edge by means of which it may be made to contact a first pin fixed in the locking housing, and the releasing lever, at its end facing away from the locking element, comprises a grooved edge which may be made to contact a further pin fixed in the locking housing, wherein the releasing lever, upon contact with said further pin, holds the edge of the locking element in contact with the first pin with minimum clearance.
3. A coupling hook according to Claim 2, wherein the locking element and the releasing lever are positively interlocked with each other by the pin which is displaceable in the triangular hole.

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4. A coupling hook according to either one of Claims 2 and 3, wherein the triangular hole is provided in a wedge-shaped part of the releasing lever.
5. A coupling hook according to any one of Claims 2 to 4, wherein the grooved edge of the underside contour of the locking element is in contact with the first pin when the grooved edge of the releasing lever is in contact with the further pin and when the pin of the locking element contacts an upper contact region of the triangular hole.
6. A coupling hook according to any one of Claims 1 to 5, wherein the releasing lever is spring-urged into a locking position between the pin of the locking element and the further pin of the locking housing.
7. A coupling hook according to any one of Claims 1 to 6, wherein the locking element is guided and pivotable around a pin, in an oblong hole, connected to the locking housing.
8. A coupling hook according to Claim 7, wherein the locking element may be fixed in the oblong hole by a securing pin insertable into a bore of the locking housing.
9. A coupling hook according to any one of Claims 2 to 5, wherein the releasing lever may be raised, with the pin of the locking element contacting a lower, rear contact region of the triangular hole and with the grooved edge of the releasing lever being positioned above the further pin.

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10. A coupling hook according to any one of Claims 2 to 5 and 9, wherein a wedge-shaped part of the releasing lever in the region of its point, is provided with a step and the step may establish an operative connection with the further pin of the housing, with the pin of the locking element contacting a lower front contact region of the triangular hole.
11. A coupling hook according to Claim 10, wherein under the pretension of the spring, the releasing lever, by means of the step of the wedge-shaped part, holds the locking element on the further pin in an open position.
12. A coupling hook according to any one of Claims 1 to 11, wherein the locking housing, at its underside, defines a large aperture and that, outside this aperture, it is welded to the hook member.

Publ shed 1991 atThe Patent Office. State House, 66/71 High Holbu.-n. IAmdonWCIR47?. Further copies may be obtained from I I Sales Branch, Unit 6. Nine Mile Poim Cwmfelinfach. Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cmy. Kent.

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