CH667178A5 - TRAILER COUPLING, ESPECIALLY FOR AGRICULTURAL OR FORESTRY VEHICLES. - Google Patents

Description

DESCRIPTION

The invention relates to a trailer coupling according to the preamble of claim 1.

Couplings can be dimensioned so that drawbar eyes of different dimensions can be coupled. The coupling mouth is then designed to fit the towing eye with the largest diameter. When coupling smaller towing eyes, they push too far into the coupling mouth, with the result that the coupling pin cannot be inserted into the mounting hole of the towing eye because the pin and the hole are not aligned with one another. The trailer must then be pushed back to engage it in order to allow the bolt to be inserted. In order to avoid this additional work step, which is also prone to accidents, it is already known for a trailer coupling of the type mentioned at the beginning (DE-OS 1 580 618, DE-GM 8 226 981) to insert an insert in the coupling mouth in the area of the coupling mouth bottom , which adapts the towing eye penetration depth to a given eye shape of the towing eye. Regardless of the problem of the play compensation of trailer couplings with design for several towing eye forms, couplings with cylindrical coupling bolts occur particularly in agricultural and forestry vehicles (in the sense of tractor-trailer combinations with a maximum speed in the range of 25 or 40 km / h). a play between the towing eye and the coupling mouth bottom. The drawbar swivels from its normal inclination position in the vertical direction to a considerable extent (e.g. ± 20 °) during driving. This is especially true for off-road driving and for trailers with relatively short drawbars. In order to allow this pivoting movement, the diameter of the receiving bore is correspondingly larger2

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sets as the diameter of the cylindrical coupling pin. In the normal inclination position of the drawbar, the drawbar eye then has a relatively large amount of play on the coupling pin, which in turn is often mounted with play on the coupling mouth, so that a total play of the drawbar eye compared to the coupling mouth can result, for example, about 12 mm. Such a large game results in an undesirably high level of noise and increased wear of the parts hitting against each other, the towing eye, coupling pin and coupling pin bore. If, in order to reduce this play of movement, the known thickness of the coupling mouth bottom is used, the problem arises that the towing eye tip facing the coupling mouth bottom generally moves increasingly away from the coupling bolt in the vertical direction during a pivoting movement from the normal inclination position . So that there is no jamming, the contact surface of the insert would have to be set back far enough towards the coupling jaw base; in the normal inclined position, this in turn results in an undesirable play in the movement of the towing eye between the coupling pin and the contact surface of the insert.

DE-AS 1 040 383 discloses a trailer coupling with an insert for eliminating play between the coupling pin and the thrust eye. An elastic band is provided as an insert, one end of which is attached laterally to the coupling pin 5 in the region between a coupling mouth wall and the coupling mouth bottom, and the other end of which is attached to a tensioning lever on the opposite sides. With the help of this tensioning lever you can obtain a sufficient pre-tension to absorb thrust shocks of the pull rod without evasion. With the lever in the tensioned position and the band shortened accordingly, the towing eye can no longer be engaged. Therefore, the clamping lever must be released before engaging. The belt can then be tensioned with an additional handle after coupling. If this trailer coupling is designed for a certain hitch size, the alignment problems mentioned above arise when using smaller hitch sizes. Finally, increased wear is to be feared, since the elastic band lies directly on the towing eye. This trailer coupling is only suitable for slight vertical swivel angles of the drawbar and for larger swivel angles a vertical joint is required, as described in DE-PS 931 212 and which is arranged between the trailer coupling mouth and the towing vehicle. However, this complicates the construction of such a trailer coupling.

From DE-PS 931 212 the above-mentioned swivel joint is known, which connects the coupling mouth with a pull rod on the vehicle. A leaf spring package ensures that the joint is pre-tensioned to a normal position, whereby the coupling jaw can be turned downwards without restoring force. The elimination of play between the coupling pin and the towing eye while allowing inclination movements when the towing rod is engaged is not addressed here.

The invention has for its object to improve a trailer coupling of the generic type while maintaining a simple, inexpensive structure with high mechanical strength and low wear with simple handling in such a way that to reduce the noise and wear, the play of the towing eye on the coupling mouth in is essentially eliminated with the possibility of inclination movements of the tie rod relative to the coupling pin.

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This object is achieved according to the invention in a trailer coupling of the type outlined in the preamble of claim 1 in connection with the features of its identification.

A simple and inexpensive construction is ensured by the fact that the insert consisting of insert plate and spring elements is only to be attached to the coupling mouth bottom. Since the forces that occur are derived directly from the insert plate via the spring elements into the cooling mouth, and moreover the rigid insert plate can be designed to be low-wear, this results in a high mechanical load-bearing capacity with little wear. Easy handling is ensured by the fact that when the clutch is engaged, the drawbar eye only has to be inserted into the coupling mouth up to the stop on the insert, whereupon the coupling pin is engaged. Any further manipulations are not necessary. Due to the elastic resilience of the spring elements, the pull rod can easily perform inclination movements in the vertical plane relative to the trailer coupling. The thrust shocks of the pull rod that normally occur during driving operation are, however, absorbed essentially without the insert plate having to be deflected due to the corresponding design of the spring elements, so that the pulling eye practically detaches from the coupling bolt during travel. This avoids the driving shocks that otherwise generate noise and cause increased wear.

In order to substantially prevent the towing eye from kicking back on the coupling bolt even in the event of very strong pressure surges, the spring travel is limited to the maximum suspension travel required for pivoting the pull rod.

In order to be able to use the coupling mouth with simple means with great mechanical stability, the measures according to claims 4 to 10 are proposed. Of particular note is the particularly simple attachment via pins (claims 4 to 7), which also has the advantage of simple assembly and, if appropriate, disassembly. When using drawbar eyes of different shapes, the insert can be exchanged quickly and easily.

Another type of fastening connection between insert and coupling mouth is specified in claims 8 to 10. The undercuts can be produced inexpensively. An additional advantage is that the undercuts protect the corresponding stop lugs protruding into them on the insert plate or on the spring element with respect to the towing eye, so that damage to these parts by the retracting towing eye is excluded from the outset.

In order to reliably prevent the insert plate from deflecting in the circumferential direction of the towing eye with a corresponding thrust load when cornering (e.g. if one of the two steering axle wheels hits an obstacle), the measures according to claim 9 are proposed.

The stop lugs according to claim 10 advantageously provide for a lateral fixing of the insert plate as well as for its attachment to the coupling mouth.

When rubber elements are used, these simultaneously form spring elements and damping elements. If the spring element according to claim 11 is made of rubber, it can have inner air chambers (in the manner of foam rubber). The suspension hardness is to be matched to the size of the pressure surges to be expected.

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667 178

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Low manufacturing and assembly costs for the rubber spring elements on the insert are guaranteed in the embodiment according to claim 12.

The invention is explained below using several preferred exemplary embodiments with reference to the drawing. It shows:

Figure 1 is a sectional side view of an inventive embodiment of a trailer hitch with a pull rod located in a normal inclination position (section along line I - I in Fig. 3).

FIG. 2 shows a view according to FIG. 1 with the pull rod pivoted downward;

Fig. 3 is a horizontal section of the trailer coupling along line III-III in Fig. 1;

4 shows a side view similar to FIG. 1 of a second embodiment;

5 shows a section similar to FIG. 3 of this second embodiment (section line V-V in FIG. 4) and

Fig. 6 is a view similar to Fig. 1 of another embodiment.

The trailer coupling 10, shown in simplified form in FIGS. 1-3 for agricultural or forestry vehicles (ie slow-moving vehicle combinations of up to 25 or 40 km / h), consists of a coupling part 12 on the towing vehicle side and a towing rod 14 on the trailer side with a towing eye 16. The coupling part 12 on the towing vehicle side consists of a coupling jaw 17 with a coupling jaw opening 18 (left in FIGS. 1-3) and the coupling jaw bottom 20 opposite the opening. By means of an actuation mechanism (not shown), a coupling bolt 22 with a substantially vertical bolt axis 24 in the direction of this axis is made of a Release position can be moved into a coupling position. In the release position, the coupling pin 22 does not protrude into the interior of the coupling mouth 26; In the coupling position according to FIGS. 1-3, the coupling pin 22, on the other hand, penetrates the interior 26. On the coupling mouth bottom there is an insert 30 to be explained below, which has an approximately cylindrically concavely curved contact surface 32, the cylinder axis of the curvature with the bore axis 34 of a coupling pin receiving bore 36 of the towing eye 16 coincides with one another in the geometric arrangement of the parts 12 and 14 according to FIGS. 1 and 3. The receiving bore 36 is formed by the interior of a cylindrical bush 38 which is pressed into a corresponding bore 40 in the towing eye 16. At both axial ends, the inner circumferential surface of the receiving bore 36 is conically beveled toward the outside, forming an edge 42 in each case. The inside diameter a of the receiving bore 36 is markedly larger than the diameter b of the coupling bolt 22 and is, for example, approximately 4/3 of b. The distance c between the two edges 42 at the two bore ends is approximately% of b. The thickness d of the towing eye 16 is exactly the same as b. Due to these dimensions, it is possible to pull the tie rod 14 from its normal inclination position shown in FIGS. 1 and 3, in which the longitudinal direction of the tie rod lies in a plane perpendicular to the axis 24, i.e. runs horizontally (axes 24 and 34 parallel to one another) in order to pivot an angle a upwards or downwards. The maximum swivel angle a can be 20:. Such swivel angles can certainly occur when driving off-road. Comparing FIGS. 1 and 2, it can be seen that the towing eye tip 44 between the coupling pin 22 and the insert 30 during the transition from the normal inclination position into the position according to FIG. 2 with the pull rod 14 pivoted downward as far as possible along with a displacement above (parallel to the axis 24) also has to perform a pivoting movement about the upper edge 42 in accordance with the angle a. Since the tip 44 has its greatest thickness equal to half the thickness d of the towing eye 16 and the edge 42 is arranged eccentrically in the area of the upper end of the bore, the apex distance e of the tip 44 increases with the transition from FIG. 1 to FIG. 2 from the pin peripheral surface 46. In the normal inclination position, this distance e is, for example, 31 mm; when the drawbar 14 is pivoted to the maximum, the distance e 'is 33 mm. The change in distance e 'minus e is small compared to the play (a minus b) of the towing eye 16 compared to the coupling jaw 17 (without insert 30) in the amount of approximately 12-13 mm.

In the normal inclination position according to FIG. 1, the towing eye tip 44 is fitted almost without play between the coupling bolts 22 and the contact surface 32 (the distance between the contact surface 32 and the bolt circumferential surface 46 in the section according to FIG. 1 is therefore e). The insert 30 can be displaced in the direction A in FIG. 1, that is to say in the direction of the coupling jaw base 20 and perpendicularly to the pin axis 24, counter-forces being increasingly generated due to the compression of a rubber plate 48 between an insert plate 50 carrying the contact surface 32 and the coupling jaw base 20 .

The rubber plate 48 consists of a layer 56 vulcanized onto the rear side 54 of the insert plate 50 opposite the contact surface 32, from which support feet project as spring elements 58, which are supported on the coupling jaw base 20. The spaces 60 formed between the spring elements 58 in the form of blind-hole-like, possibly cylindrical cavities open towards the bottom 20 form alternative spaces into which the spring elements 58 partially penetrate when they are compressed in the direction A. Due to the use of rubber as the suspension material, the deflection movement of the insert plate 50 is damped at the same time.

The insert plate 50 is mounted in the direction A on the coupling jaw 17 by means of two mutually aligned pins 64 parallel to the pin axis 24. The pins 64 designed as drive-in pins penetrate the upper and lower coupling jaw walls 66, 68 near the coupling jaw base 20. In order to maintain the mobility of the insert plate 50 in direction A, these pins 64 each pass through an elongated hole 70 oriented in direction A in an upper and lower, each of the upper and lower edge strips 72, 74 of the insert plate 50 protruding at right angles from the contact surface 32 in the direction of the coupling jaw opening 18. In FIG. 5, the lower edge strip 74 is indicated in broken lines together with the elongated hole 70 and pin 64. The length of the two elongated holes 70 is such dimensioned that the movement of the pins 64 essentially corresponds exactly to the required travel (e 'minus e).

The installation of the insert 30 is quick and easy (no special tools are required). Only the insert 30 has to be placed on the coupling jaw base 20; the two pins 64 are then hammered in from the outside in. The coupling of the towing eye 16 is extremely easy since the towing eye 16 can only be moved as far as the stop against the contact surface 32, which due to its cylindrical curvature (FIG. 3) the towing eye 16 in its position both with respect to the insertion direction A and in this 3 in the vertical horizontal direction (direction B in FIG. 3), in such a way that the coupling pin 22 can move into the receiving bore 36, sliding along the point of the inner bore circumference closest to the towing eye tip 44. The Zugösenspitze 44 is therefore almost free of play when the coupling pin 22 is coupled between the coupling pin 22 and the insert plate 50. During the

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As a result, jerky relative movements between the towing eye 16 and the coupling pin 22 and between the coupling pin 22 and the bore 25 in the coupling mouth 17 for the pin 22 are avoided or at least severely restricted. Such relative movements result in greatly increased wear and often extremely unpleasant noise. The resilience of the rubber plate 48 is so high that there is only a slight deflection of the insert 30 in direction A when there are very strong pressure surges. In this way, the evasive movement is approximately limited to the lowest possible value, namely the value e 'minus e, which is required to allow the pull rod 14 to be pivoted downwards or upwards from the normal inclination position according to FIG. 1, up to a maximum of one pivoting position is achieved with an angle a according to FIG. 2. In the case of very strong impacts, mainly when engaging, the lowest possible value can also be exceeded slightly for a short time.

A further embodiment of a trailer coupling is shown in FIGS. 4 and 5 and designated 110. Components of this coupling, which have the same structure and function in components of the coupling according to Figures 1 to 3, are given the same reference numerals, each increased by the number 100. The basic structure of towing eye 116 with pull rod 114 and coupling jaw 117 together with coupling bolt 122 and insert 130 inserted into the coupling jaw is approximately the same as for coupling 10. However, the type of mounting of insert 130 on coupling jaw 117 is different.

As shown in FIG. 4, the rubber plate 148 forming the spring element is provided on the rear and rear side of the insert plate 150 on the upper and lower edge with an upward and downward projection 180, respectively, which each protrudes into a corresponding undercut 182 on the upper one or lower edge of the coupling mouth bottom 120 engages in a form-fitting manner. Because of their elastic flexibility, the projections 180 give way briefly when the insert is mounted within the coupling mouth, in order then to snap into the undercuts 182 assigned to them. In the starting position according to FIGS. 4 and 5 (normal inclination position of the pull rod 114 without pressure load), the insert 130 is at a distance from the coupling jaw base 120 on all sides in the retracting direction A of the pull rod 114; If a force acting in direction A is exerted on the towing eye 116 lying on the insert plate 150 or only a short distance from the insert 130, this leads to a compression of the rubber plate 148 with a corresponding displacement of the insert 130 in the figures 4 and 5 to the right towards the coupling mouth bottom 120. The desired resilient-elastic flexibility of the insert 130 is therefore given.

Under certain circumstances, forces acting on the insert 130 in the circumferential direction (<-> arrow in FIG. 5) of the drawbar eye 116 can be exerted by the drawbar eye, for example when one of the two wheels of the steered axle connected to the drawbar 114 is on Obstacle and subsequently pull rod 114 experiences a side impact. In order to hold the insert 130 in place in these cases, the insert plate 150 is provided with lateral stop lugs 186, which engage in lateral recesses 188 of the coupling mouth 117, which are associated therewith, on the side of the coupling jaw base 120. 4, the stop lugs 186 are approximately halfway up (parallel to the axis 124 of the coupling bolt 122 of the coupling jaw opening 118). At a force attempting to move the insert plate 150 in direction B, one strikes

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of the two stop lugs 186 with their nose end on a stop surface 193 of the recess 188 which is parallel to the axis 124 and to the horizontal longitudinal axis 190 (corresponding to the orientation of the longitudinal axis of the pull rod 114 when the towing vehicle pull rod arrangement is extended).

FIG. 6 shows a further coupling embodiment, designated 210, wherein components with the same reference numbers as the corresponding components in FIGS. 1 to 3 are again provided with the number 200 this time. The difference to the couplings 10 and 110 again lies in the different way in which the insert 230 is mounted on the coupling mouth 217. Here, the insert plate 250 is provided with lateral projections as stop lugs 292 (at the same location as the stop lugs 186 according to FIGS. 4 and 5); However, the stop lugs 292 not only serve to fix the insert 230 laterally in the coupling mouth 217 but also also to fasten the insert 230. For this purpose, the two stop lugs 292 engage in assigned through-openings as recesses 294 in the respective coupling mouth side wall 296 which adjoins the coupling mouth bottom 220 laterally a. The stop lugs 292 engage behind the outer edges of the continuous recesses 294 and thus fix the insert plate 250 to the coupling mouth 217. In addition to the inner side surfaces 297 of the recesses 294 parallel to the pin axis 224 and parallel to the pin axis 224, the stop lugs 292 hold the desired movement play of the insert 230 in the entry direction A. corresponding distance (in the starting position according to FIG. 6). The approximately S-shaped curved stop lugs 292 serve, in accordance with the stop lugs 186, to prevent lateral movement of the insert plate 250. They are designed to be resilient in such a way that, on the one hand, they can be bent briefly when inserting the insert 230 for insertion into the continuous recesses 294, and on the other hand after snapping into the recesses 294, hold the insert securely there.

To adapt to a different eyelet shape, the inserts of the embodiments 10, 110, 210 described above can be removed without difficulty and, if necessary, replaced by a differently shaped insert. To remove the insert 230 according to FIG. 6, for example, it only has to be levered out accordingly by engagement of a screwdriver along one of the two side walls 296 in the space between the insert plate 250 and the side wall above or below the stop nose 292 formed there as a projection. However, one can additionally or alternatively, press one of the two stop lugs 292 inwards from the outside until it comes out of engagement with the recess 294.

The inserts described above can also be successfully used in trailer couplings in which the pull rod does not have to be able to carry out such large inclination changes with respect to the coupling bolt, that is to say has less play with respect to the coupling bolt. In this case, too, the elastically resilient insert is approximately free of play or less pretensioning at the coupling pin tip, so that the necessary, albeit comparatively much smaller, clearance of the coupling pin within the receiving bore and the coupling pin play in the coupling jaw bore are not appropriate abrupt relative movements between the coupling eye and coupling mouth lead while driving.

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2 sheets of drawings

Claims (13)

667 178 PATENT CLAIMS 1. Trailer coupling, in particular for agricultural or forestry vehicles, with an insert (30) in the coupling mouth (17) to adapt to the depth of penetration of the respective towing eye (16) provided on a pull rod (14), which is located on the Coupling jaw opening (18) supports opposite coupling jaw bottom (20) and has a towing eye contact surface (32) in the area of the coupling jaw bottom (20) which is essentially parallel to the pin axis (24) of the coupling bolt (22) of the trailer coupling, characterized in that the insert (30 ; 130; 230) comprises an essentially rigid insert plate (50; 150; 250;) which supports the contact surface (32) and which is supported on the coupling mouth base (20; 120; 220) by at least one spring element and on the coupling mouth Movement play in direction (A) is mounted perpendicular to the coupling jaw base (20; 120; 220) in such a way that in a normal inclination position the coupled pull rod (14; 114) in which the bore axis (3rd 4) the coupling pin receiving bore (36) of the drawbar eye (16; 116) runs essentially parallel to the coupling pin axis (24; 124; 224), the towing eye (16; 116) fits essentially free of play between the coupled coupling pins (22; 122; 222) and the insert plate (50; 150; 250) and when the pull rod (14; 114; 214) swivels in the vertical plane from the normal inclination position, the insert plate (50; 150; 250) under the pressure of the pulling elements increasingly penetrating into the coupling mouth (17; 117; 217) The eyelet tip (44) can deflect towards the coupling jaw base (20; 120; 220) by compressing the at least one spring element (58), the restoring force of the at least one spring element (58) being dimensioned such that thrust shocks of the pull rod (14 ; 114) are caught essentially without the insert plate (50; 150; 250) deflecting towards the coupling jaw base (20; 120; 220). 2. Trailer coupling according to claim 1, characterized in that the spring travel of the insert (30) in direction (A) to the coupling jaw base (20) essentially to the value of the change in the penetration depth of the towing eye (16) at maximum pivoting the pull rod (14) is limited from the normal inclination. 3. Trailer coupling according to claim 1 or 2, characterized in that the insert plate (50; 150; 250) is formed from sheet steel. 4. Trailer coupling according to claim 3, characterized in that the insert plate (50; 150; 250) on the coupling jaw (17; 117; 217) is releasably mounted with play in direction (A) perpendicular to the "coupling jaw bottom (20) . 5. Trailer coupling according to claim 4, characterized in that the insert plate (50) is attached to the coupling mouth (17) via at least one slot bolt connection. 6. Trailer coupling according to claim 5, characterized in that on the upper and lower coupling jaw wall (66, 68) penetrated by the coupling bolt (22) near the coupling jaw base (20) to the bolt axis (24) parallel, preferably aligned pins (64) , preferably drive-in pins, which each engage in an elongated hole (70) of the insert plate (50) running in the direction (A) at right angles to the coupling mouth base (20). 7. Trailer coupling according to claim 6, characterized in that the elongated hole is present on an edge strip (74) of the insert plate (50) which is essentially rectangular to the pin axis (24). 8. Trailer coupling according to claim 4, characterized in that the insert plate (250) and / or the spring element (148) via at least one undercut (182; 294) in the wall (296) of the coupling mouth (117; 217) is mounted . 9. Trailer coupling according to claim 8, characterized in that the insert plate (150; 250) is formed with lateral stop lugs (186; 292) which in associated recesses (188; 294) in the wall of the coupling mouth (117; 217) intervene to fix the insert plate in the coupling mouth with respect to movements of the insert plate approximately in the circumferential direction (B) of the towing eye (116; 216). 10. Trailer coupling according to claim 9, characterized in that the stop lugs (292) engage behind the associated recesses (294). 11. Trailer coupling according to claim 1, characterized in that the at least one spring element (58) consists of rubber and has inner air chambers. 12. Trailer coupling according to claim 1, characterized in that a rubber plate (48) is attached, preferably vulcanized, on the insert plate back (54) facing the coupling jaw base (20), from which spring elements (58) towards the coupling jaw base (20) protrude. 13. Trailer coupling according to one of the preceding claims, characterized in that the contact surface (32) is essentially cylindrically concavely curved with a cylinder axis which, with the bore axis (34) of the towing eye (16) located in the normal inclination position, essentially coincides.