A COUPLING ARRANGEMENT BETWEEN A TOWING VEHICLE AND A TRAILER VEHICLE

Abstract: A coupling arrangement between a towing vehicle (1) and a trailer vehicle (17) includes a towing device (2, 10) which is connected to the towing vehicle. The towing device is provided with a towing member (10) arranged to engage a curved abutment surface (20) on the trailer vehicle. The abutment surface comprises two circular-arcuate edge sections (20a, 20b) located on engagement means (21). The towing member comprises two rolling, or non-rolling towing elements, for example in the form of runners (11, 12) which are arranged to be urged against the curved abutment surface (20) under the action of the force-generating means (5, 6 and 140 respectively). When the towing vehicle turns from a straight forward movement direction, the towing elements (11, 12) move along each of the circular-arcuate edge sections (20a, 20b) from a first position (Fig. 3), in which the two towing elements are located on a respective one of the circular-arcuate edge sections, to a second position (Fig. 4), in which both of the towing elements are located on the same edge section. The towing elements (11, 12) are either supported by an individual respective holder (110a, 110b), or by a common holder (10).

Description: A coupling arrangement between a towing vehicle and a trailer vehicle. TECHNICAL FIELD The present invention relates to a coupling arrangement between a towing vehicle and a trailer vehicle, comprising "a towing device which is connected to the towing vehicle and which is provided with a towing member capable of enga¬ ging a curved, substantially vertically extending engage¬ ment surface located on an engagement means rigidly connec¬ ted to the towed vehicle. BACKGROUND ART It is desirable in this art to reduce the distance between a towing vehicle and a trailer connected thereto, so as to be able to optimize the effective load-carrying length of the platforms of transport vehicles. On the other hand, this- distance must be sufficient to allow the towing vehic¬ le to turn freely, without obstruction. In one known coupling arrangement which minimizes this distance, the towing device mounted on the towing vehicle is provided with a link roller intended for rolling engage¬ ment with a curved guide bar mounted on the trailer or towe vehicle. It has been possible in this way to reduce the distance between towing and towed vehicles, when moving forward in a straight line, to about 20 cm. Due to the combination- of the link roller and curved guide bar, the distance between the two mutually connected vehicles will namely increase when the vehicles turn, therewith providing sufficient turning space. One disadvantage with this known arrangement, however, is that a clearance which cannot readily be overcome or con¬ trolled occurs between the link roller and the curved guide bar. Another disadvantage is that the known coupling arran¬ gement lacks a stable guide position when the vehicles move forwards in a straight line, since the link-roller springs of the known arrangement strive to move the link roller to one side of the guide bar or the other. This forces the trailer to swing from side to side as it moves along. SUMMARY OF THE INVENTION The object of the present invention is therefore to provide a coupling arrangement of the aforesaid kind with which the aforementioned disadvantages are avoided. This object is achieved by means of a coupling arrangement constructed in accordance with the present invention and having the charac¬ teristic features set forth in the following Claim 1. Further developments of the invention are set forth in the depending claims. Because the coupling arrangement according to the invention incorporates ' a towing device which comprises two towing members which are pressed against the " curved abutment sur¬ face by force-generating means and which together can move along said curvedabutment surface, there is obtained an improved abutment pressure and, at the same time, possibili¬ ties are provided for enabling the ' twα towing members to be located symmetrically, or asymmetrically, in relation to the longitudinal, vertical centre plane (symmetry plane) of the trailer vehicle, therewith to provide a stable, or labile relative position between towing members and the curved abutment surface. It will also be seen that such a coupling arrangement can be used in connection with practi¬ cally all trailer vehicles. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to two embodiments thereof illustrated in the accompanying drawings; in which Figure 1 illustrates schematically and in perspective the towing device of a towing vehicle, this device being con¬ structed in accordance with a preferred embodiment of the invention; Figure 2 is a schematic perspective view of the engagement means of the trailer vehicle according to the preferred embodiment; Figures 3 and 4 illustrate respectively the preferred embo¬ diment of the coupling arrangement in a first position, in which the vehicles move straight forwards, and in a second position in which the vehicles are shown to turn from the straight forward direction; Figure 5 is a schematic view in perspective of an alterna¬ tive embodiment of a towing device of the towing vehicle an the engagement, or hook-up means of the trailer vehicle; Figure 6 is a modified towing member for the towing device illustrated in Figure 5; and Figure 7 is a schematic, perspective view of the trailer engagement means of the alternative embodiment. DESCRIPTION OF A PREFERRED EMBODIMENT Fig. 1 illustrates schematically a towing device mounted on a- schematically illustrated towing vehicle 1. The towing device includes a forwardly located towing assembly, as seen in the towing direction of the towing vehicle, compri¬ sing a tow-bar 2 whose forward end is connected to the towing vehicle 1 through a substantially vertically exten- ding pivot shown schematically at 3, and whose rearward end has the form of a bifurcate or pronged structure which comprises two legs or prongs 2a and 2b and with which the forward part of -the.open space defined between the prongs is covered by an upper and a lower cover plate 4 respectively (of which only the upper cover plate is shown) , these cover plates being fastened to respective prongs 2a and 2b " by fastener means not shown. The towing device also comprises a rearwardly located towing assembly comprising a piston bar 5., which is of square cross-section and which co-acts telescopically with a working cylinder located between the prongs 2a and 2b of the bifurcate structure and extending coaxially with the tow-bar 2. The working cylinder 6 is secured to the cover plates 4 by means of a peg 7. In the preferred embodiment, the working cylinder 6 and the piston bar 5 form a conventional gas spring of known design. This gas spring forms the aforesaid force-generating means. Alte natively, the illustrated gas spring may be replaced with, for example, a hydraulic piston-cylinder device or with some " . form of pressure spring other than the described gas spring. When towing a conventional trailer (not shown) , the tow- bar 2 is allowed.to swing about the pivot axis 3. When usin the coupling arrangement according to the invention, howeve such swinging motion is blocked with the aid of suitable blocking means, i.e. the tow-bar 2 is rigidly connected to the towing vehicle. In the Fig. 1 embodiment the blocking means comprises a frame-member construction in the form of a so-called under-ride 'guard 8 '- which is pivotally arran ged so that it can swing from its normal, vertical position in which it functions in a known manner as a means of under ride protection against hazardous driving when running-in small vehicles, to a substantially horizontal position (illustrated in Fig. 1) in which it blocks rotation of the tow-bar through the agency of a respective shoulder 8a and 8b located on an associated side of the tow-bar. The free end of the piston bar 5 is rigidly connected, for example welded, to a vertical upstanding pivot shaft 9, on which a tow-member holder 10 is pivotally mounted. The holder 10 comprises two mutually identical triangular plate 10a and 10b which are arranged horizontally one above the other in parallel spaced relationship, and which have rota- tably mounted therebetween two vertically extending tow- members in the form of two runners 11 and 12, the aforesaid pivot shaft being located in a vertical symmetry plane passing through the holder 10, between the runners 11 and 12. The tow-bar 2 is located centrally of an outrigger construc tion which comprises two pairs of beams 13a, 14a and 13b, 14 connected to a respective side of the tow-bar and extending outwardly therefrom. The beams of each pair of beams are mutually joined to form a U-shaped configuration, and the forward beams 13a and 13b of each beam pair project slightl beyond the ends of respective rearwardly located beams 14a and 14b adjacent thereto, and are there provided with respe tive U-shaped seats 15 and 16 for receiving an associated pivot shaft 18 and 19 rigidly mounted on the schematically indicated trailer vehicle 17. The runners 11 and 12 lie against and are able to run along a substantially vertically arranged, curved abutment surfac 20, shown schematically in Fig. 1 , on a cam-plate like enga gement means 21 which is rigidly connected to the trailer vehicle and which is shown more clearly in Fig. 2. The - abutment surface 20 comprises two circular-arcuate sections which converge rearwardly as seen in the forward drive dire tion of the towing vehicle. The sections 20a, 20b extend symmetrically along a respective side of the vertical longi tudinal centre plane of the vehicle (the symmetry plane) . The radius R (Fig. 3) of each circular-arcuate section 20a, 20b is measured from the respective pivot shaft 18 and 19 and is the same for both sections. As shown in Fig. 2, the engagement means 21 is welded at its upper surface to the upper inner surface of two vertica beam frames 22 and 23, which are welded to the undersides o two longitudinally extending supporting beams 24 and 25 on the trailer vehicle 17. The openings presented by the beam frames 22 and 23 are adapted to accommodate both the engage ment means 21 and the tow device 2, said device being inten ded to be inserted beneath the engagement means 21 , so that the upstanding runners 11 and 12 can run along the abutment surface 20 of the engagement means 21, as indicated in Fig. 1. The vertical parts of the beam frame 22 comprise the afore¬ said pivot shafts 18 and 19, which form journalling means for the outrigger 13a, 13b of the tow-bar when turning the towing vehicle (c.f. also Fig. 4) . The engagement means 21 comprises a beam which is curved to the aforesaid circular-arcuate shapes (alternatively comprises two beams combined to form said circular-arcuate shapes) , the vertical, curved outer surfaces of which beam form said curved abutment surfaces 20a, 20b extending sym¬ metrically on respective sides of the longitudinally exten- ding, vertical centre plane A of the trailer vehicle 17 (this centre plane being shown with a broken line in Fig. 3) The beam 21 is strengthened with a forward (seen in the towing direction of the towing vehicle) and a rearward transverse beam 26 and 27 respectively. Extending from the forward beam 26 forwardly along said centre plane A is a beam 28 from which there extends obliquely forwardly from both sides thereof an outriqqer beam 29 and 30 respectively against which the free ends of the beam 21 are attached at some distance from the ends of the outrigger beams 29,30, so that the intersection line between the curved abutment surfaces and the outrigger beams 29,30 form stop positions 31 and 32 for movement of the runners 11, 12. The beam 28-30 are duplicated by placing similarly eon- structed beams 28' , 29' and 30' uniformly beneath the beams 28-30 at a distance therefrom corresponding to the thicknes of the tow-bar 2 , so as to enable the tow-bar to be inserte between the two aforesaid beam arrays. The forward ends of the beams 28-30 and 28'-30' are fastened to a transverse, horizontal beam 33 and 34 respectively, between which there is formed a so-called hitch-up orifice for the tow-bar 2. The beams 21,26-39, 33-34 are rigidly connected to one another by means of some suitable joint, for example a weld joint. Similarly, the tow-bar 2 and the outriggers 13,14 are rigidly connected together by means of some suitable joint, not shown. The undersides of the beams 28-30 and the upper sides of the beams 28" -30' are intended to form support surfaces for a support roller 35, which is journalled on a shaft 35a extending between the prongs 2a and 2b of the bifurcate structure (see Fig. 1) . The support roller 35 extends some¬ what, for example 5 mm, beyond the upper and lower surfaces of the tow-bar 2. When the towing vehicle turns from a straight forward direction (see Fig. 4) the support roller will therefore roll between the beams 28 and 28', and thereafter between the beams 29 and 29', or between the beams 30 and 30' . The support roller 35 thus moves along an arcuate line 36, from one position 35' to another posi¬ tion 35", as indicated in Fig. 4. With the tow-bar 2 inserted with its seats 15,16 in engage¬ ment with the pivot shafts 18,19, the rollers or runners 11,12 will each lie against a respective one of the circu¬ lar-arcuate sections 20a and 20b on each side of the symme- try plane A as illustrated in Fig. 3. The gas spring 5,6 therewith holds the runners 11,12 pressed against a respec¬ tive section 20a, 20b, so that the runners 11,12 will-also exert a force which is directed obliquely to the symmetry plane A and which endeavours to maintain the relative posi¬ tion (the stable position) illustrated in Figs. 1 and 3 between the tow-bar 2 and the engagement means ("the cam disc") 21. The operational mode of the coupling arrangement is best seen from Figs . 3 and 4. When the vehicle train moves in a straight forward direction, cf. the arrow in Fig. 3, the tow-bar 2 and the "cam plate" 21 occupy the stable, steerin damping position illustrated in Fig. 1. When the towing ve¬ hicle 1 turns away from the straight forward direction, cf. the arrow in Fig. 4, the tow-bar 2 will rotate about the pivot shaft 19, while overcoming the force exerted by the gas spring 5,6, and will release its engagement with the pivot shaft 18. The runners 11,12 therewith roll over the same section 20a, cf. Fig. 4. . * When the towing vehicle and the trailer vehicle straighten up, the runners 11,12 roll back along the section 20a, whereupon the seat 15 of the tow-bar 2 again engages the pivot shaft 18. A corresponding movement pattern is execu- ted when the towing vehicle reverses . Figs. 5 - 7 illustrate an alternative embodiment of the invention, in which the tow-bar 2 and the cam plate 21 have been replaced with two towing plates 102a and 102b, and with a cam plate 121 respectively. The towing plate 102a is pivotally connected to the towing vehicle on a substan¬ tially horizontal pivot 137, which is oriented substantial¬ ly perpendicularly to the driving direction. The towing plates 102a and 102b are pivotally connected to one another, by means of a pivot device which is oriented substantially in the direction of vehicle travel. The cam plate 121 is connected to the beam frames 22 and 23 in a manner similar to the cam plate 21 , although in this case to the lower in¬ ner surface of the frames 22, 23 instead. The towing plate 102b will therewith be -arranged above the cam plate 121, in¬ stead of beneath the same. The rearwardly located part of the towing plate 102b (as seen in the movement direction of the towing vehicle 1 ) has arranged thereon a pivot shaft 139, which is firmly welded to the undersurface of the plate 102b. Two towing links 110a and 110b are pivotally connected to the shaft 139. Each of the links 110a and 110b carries at one end thereof a respective towing roller 111 and 112 respectively. Thus, in this embodiment each of the rollers 111 and 112 is carried • in its respective individual holder 110a and 110b, as distinct from the former embodiment, in which the rollers 11 and 12 are carried by the common holder 10. A force generating means is connected between the other ends of the links 110a and 110b, such that said means endeavours to draw the towing rollers 111 and 112 towards one another. The force-generating means of the Fig. 5 embodiment has the form of a pull spring 140,. whereas in the Fig..6 embodiment said force-generating' means has the form of a hydraulic or pneumatic piston-cylinder device 140' . In this latter embodi ment, the rectilinear ' links 110a and 110b have been replaced with angled arms 110a' and .110b' respectively. When the towing vehicle 1 turns in a manner corresponding to that illustrated in Fig. 4, the towing plate 102b rotates about the pivot shaft 119, while overcoming the. force exer- ted by the spring 140, whereas the towing plate 102b relea¬ ses its engagement with the pivot shaft 118. The towing rollers 111 and 112 therewith roll along the same section 120a, said rollers being, at the same time, forced slightly apart. The function is, in other respects, the same as that described with reference to the embodiment illustrated in Figs . 1 - ' 4. Although the two towing members 11,12 and 111, 112 of the illustrated embodiments have the form of runners and draw- rollers respectively, it will be .obvious to those skilled in this art that said rollers can be replaced with other rolling or non-rolling towing members. For example, these members may comprise two arcuate rods (in the alternative embodiment) arranged for movement relative to one another, or with suitable slide bodies capable of sliding along the curved abutment sections 20a, 20b and 120a, 120b respecti¬ vely. It will also be readily perceived that the force- generating means 5,6 and 140 and 140' can be constructed to exert an adjustable force.

Claims: ' CLAIMS 1. A coupling arrangement between a towing vehicle (1) and a trailer, vehicle (17) , comprising a towing device which is connected to the towing vehicle and which is provided with a towing member (10) capable of engaging a curved, substantially vertically oriented abutment surface (20) on an engagement means (21) rigidly connected to the trailer vehicle, characterized in that the curved abutment surface comprises two circular-arcuate edge sections (20a, 20b) on the engagement means (21), each of said edge sections being located on a respective side of the longitudinally exten¬ ding plane extending vertically through the centre of the trailer vehicle; in that the towing member includes two towing elements (11,12) which are movable along the curved abutment surface; in that the towing device is provided wit a force-generating means (5,6) capable of urging the two towing elements against the curved abutment surface; and in that the two .towing elements are together capable of moving along the curved abutment surface from a first position (Fig. 3) , in which the two towing elements are located on a respective one of said circular-arcuate edge sections, and where the towing and trailer vehicles are located in line with one another, to a further position (Fig. 4) in which the two towing elements are both located on the same edge section and where the towing and trailer vehicles are swung out of line in relation to one another. 2. A coupling arrangement according to Claim 1 , characteri¬ zed in that the towing elements (11,12) are arranged for movement along the curved abutment surface. 3. A coupling arrangement according to any one of Claims 1-2, characterized in that the two towing elements (11,12) are carried by a holder (10, Fig. 1) which is common to both towing elements and which is pivotally mounted on a substantially vertically oriented pivot (9) . 4. A coupling arrangement according to Claim- 3, characteri¬ zed in that the towing device includes a forward (2) and a rearward (5) towing assembly - as seen in the movement direction of the towing vehicle - , said two towing assemb- lies being in force-transmitting connection with one another; and in that the rearward towing assembly is arrange to effect a telescopic movement in relation to the forward towing assembly; and in that the rearward towing assembly is rigidly connected to said pivot (9) . 5. A coupling arrangement according to Claim 4, characteri¬ zed in that the rearward towing assembly comprises a piston bar (5) , said telescopic movement being effected by telesco pic action of the piston rod relative to a working cylinder (6) which is rigidly connected to the forward towing assemb (2) , said working cylinder and said piston bar together for ming said force-generating means. 6. A coupling arrangement according to Claim 5, characteri- zed in that the working cylinder (6) and the piston bar (5) together form a gas spring. 7. A coupling arrangement according to Claim 1 , characteri¬ zed in that the two towing elements (11 ,12) are each carrie by a respective individual holder (110a, b , Figs. 5-6); and in that the two holders are arranged to bring the towin elements towards one another against the action of the forc generating means (140) . 8. A coupling arrangement according to any one of the preceding claims, characterized in that the towing device (2) is rigidly connected to the towing vehicle (1) by means of a rotational movement blocking means (8) .

Inventors: HENRIKSSON ARNE, JOENSSON RUNE, HENRIKSSON, ARNE, JOENSSON, RUNE
Applicants: KALMAR LAGAB AB
Application year: 1985
Main classification: B60D1
IPC codes: B60D1, B62D13