GB2068865A - An assembly for coupling a trailing vehicle to a prime mover - Google Patents

Abstract

An assembly for coupling a trailer 13 to a prime mover comprises a gooseneck 19 attached to the trailer, a compensating member 21 coupling the gooseneck to the prime mover, and at least one hydraulic cylinder 29 positioned between the compensating member and the gooseneck or the trailer or the prime mover whereby the load supported by the prime mover is maintained substantially constant. As shown the compensating member 21 is pivoted at 25 to the gooseneck 19. In an alternative embodiment, the compensating member is constituted by a fifth wheel pivotally moulded for raising and lowering movement. <IMAGE>

Description

SPECIFICATION An assembly for coupling a trailing vehicle to a prime mover.

This invention relates to an assembly for coupling a trailing vehicle to a prime mover.

In a conventional prime mover-semitrailer combination, the trailer is fitted with a gooseneck which is coupled to a fifth wheel of the prime mover. The coupling arrangement allows pivotal movement between the prime mover and the trailer about a vertical axis for negotiation of curves.

The coupling arrangement does not, however, allow pivotal movement about a horizontal axis transverse to the direction of travel of the prime mover-trailer combination. Therefore, as the prime mover-trailer combination travels over roads of varying levels, the load imposed on the prime mover by the trailer varies. More specifically in instances where the level of the prime mover relative to the trailer rises due to an upward incline in the road surface, the forward end of the trailer also rises, removing at least a portion of the load supported by the forward road wheels of the trailer and imposing the load on the prime mover and rearward road wheels of the trailer.

Similarly, in instances where the level of the prime mover relative to the trailer drops due to a fall in the level of the road surface, the load supported hy the prime mover is reduced; that portion of the load removed from the prime mover is imposed on the ground wheels of the trailer.

Variations in the magnitude of the load supported by the prime mover are undesirable.

It is an object of this invention to provided an assembly for coupling a trailing vehicle to a prime mover whereby the load supported by the prime mover is maintained substantially constant.

In one form the invention resides in an assembly for coupling a trailing vehicle to a prime mover comprising a gooseneck attached to the trailer, a compensating member coupling the gooseneck to the prime mover, and at least one hydraulic cylinder positioned between the compensating member and the gooseneck or the trailer or the prime mover whereby the load supported by the prime mover is maintained substantially constant.

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings wherein: Figure 1 is a schematic elevational view of a prime mover-trailer combination incorporating a coupling assembly according to the invention, the prime mover-trailer combination being shown travelling over a section of road of uneven surface.

Figure 2 is a schematic elevational view of a prime mover-trailer combination incorporating a conventional coupling assembly, the prime mover-trailer combination being shown as travelling over a section of road of uneven surface.

Figure 3 is an elevational view of one embodiment of the invention.

Figure 4 is a plan view of the embodiment of Fig. 3.

Figure 5 is an elevational view of a further embodiment of the invention.

Figure 6 is an elevational view of a still further embodiment of the invention.

Referring to Fig. 1 of the drawings, there is shown a prime mover 11 to which a trailer 1 3 is coupled by means of a coupling assembly 1 5. The trailer 1 3 is of the multi-axled type, having ground wheels 1 7. The forward end of the trailer is supported by the prime mover.

The coupling assembly 1 5 is arranged to permit relative pivotal movement between the prime mover 11 and the trailer 1 3 about a horizontal axis transverse to the direction of travel of the prime mover-trailer combination so as to accommodate variations in the level of the road surface, while also maintaining the load supported by the prime mover substantially constant.

Fig. 2 of the accompanying drawings illustrates a prime mover-semitrailer combination incorporating a conventional coupling assembly 15'. As shown in Fig. 2, in instances where the prime mover 11' rises due to an upward incline in the road surface, the forward end of the trailer 13' also rises, removing at least a portion of the load supported by the forward ground wheels of the trailer and imposing the load onto the prime mover and the trailing axles. Similarly, in instances where the level of the prime mover 11' relative to the trailer 13' falls due to a fall in the level of the road surface, the load supported by the prime mover is reduced.It can therefore be seen that in a prime mover-trailer combination incorporating a conventional coupling assem- bly, the load supported by the prime mover varies in accordance with variations in the level of the road surface.

Referring now to the embodiment illustrated in Figs. 3 and 4 of the accompanying drawings, the coupling assembly comprises a gooseneck 1 9 attached to the trailer 1 3 and a compensating member 21 coupling the gooseneck to the prime mover. In this embodiment, the compensating member 21 comprises a beam structure 23 pivotally mounted at a pivot 25 intermediate its ends onto the gooseneck for rotation about a horizontal axis transverse to the direction of travel of the prime mover-trailer combination. The forward end 23a of the beam structure is adapted for coupling in the conventional manner to the fifth wheel 27 of the prime mover 11. A pair of transversely spaced hydraulic cylinders 29 are pivotally connected between the rear end 23b of beam structure and the gooseneck.

The hydraulic cylinders 29 form part of a hydraulic circuit which also includes a hydraulic fluid reservoir (not shown), a pressure relief valve 31 and a hydraulic fluid pump 33 (Fig.

1). The pump 33 is adapted to supply hydraulic fluid to the cylinders 29 at a prescribed pressure. The pump is preferably a so-called constant running pump whereby the pump operates continuously during operation of the prime mover-trailer combination while only effecting fluid pumping when the fluid pressure in the hydraulic circuit drops below said prescribed pressure. The pumping action ceases when the prescribed pressure is arrived at. The pressure relief valve 31 is adapted to open to allow release of fluid pressure in the hydraulic circuit when the prescribed pressure is exceeded, a return line (not shown) being provided to return hydraulic fluid released on opening of the valve 31 to the fluid reservoir.

The relief valve 31 and the pump 33 are therefore arranged to maintain a substantially constant fluid pressure in the cylinders 29. If, for example, the prescribed pressure is exceeded, the relief valve opens to allow pressure release until the prescribed pressure is attained. On the the other hand, if the fluid pressure in the cylinders 29 falls below the prescribed level, the pumping cycle of the pump 33 commences so as to return the pressure to the prescribed level and thereafter terminates. The relief valve is preferably provided with an adjusting mechanism whereby the prescribed pressure at which the valve operates to release fluid pressure is selectively variable.Similarly, there is preferably provided means whereby the fluid pressure at which the pumping cycle of the pump ceases may be adjusted to correspond to the operative pressure of the relief valve.

Because of the substantially constant fluid pressure maintained in the hydraulic cylinders 29, the cylinders exert a substantially constant force on the beam structure, the magnitude of which force is variable by adjustment of the operative pressure of the relief valve 31. The magnitude of the force applied to the beam structure by the cylinders is commensurate with the reaction force normally applied to the beam structure by the prime mover to thereby maintain the beam structure in an equilibrium condition; said reaction force normally applied to the beam structure being that reaction force applied when the prime mover-trailer combination is travelling along a substantially level road surface.

In instances where the prime mover 11 moves upwardly relative to the trailer 1 3 (as illustrated in Fig. 1) due to an upward incline in the road surface, the consequent momentary increase in the reaction force applied to the beam structure by the prime mover effects pivotal movement of the beam structure relative to the gooseneck in the direction which causes retraction of the cylinders 29. The retraction of the cylinders 29 in turn results in an increase in fluid pressure in the cylinders and consequently opening of the relief valve 31. The cylinders 29 therefore do not prevent pivotal movement of the beam structure relative to the gooseneck 1 9 but rather exert a substantially constant force on the beam structure during said pivotal movement.The pivotal movement of the beam structure provides for relative pivotal movement between the prime mover and the trailer to accommodate the variation in level of the road surface.

Throughout the pivotal movement of the beam structure, the cylinders exert a substantially constant force on the beam structure and the load supported by the prime mover is maintained substantially constant.

In instances where the prime mover 11 moves downward relative to the trailer 1 3 due to a fall in the level of the road surface, the forward end of the beam structure 23 is caused to move downwardly with the prime mover and thus pivotal movement of the beam structure relative to the gooseneck 1 9 is effected in the direction which causes extension of the hydraulic cylinders 29. The extension of the cylinders produces a momentary reduction in the fluid pressure which is subsequently compensated for by operation of the hydraulic pump 33 as described earlier. The cylinders therefore exert a substantially constant force (the magnitude of which is determined by the fluid pressure) on the beam structure during pivotal movement of the beam structure.As before, the pivotal movement of the beam structure provides for relative pivotal movement between the prime mover and the trailer to accommodate the variation in level of the road surface.

From the foregoing it is evident that the interaction of the hydraulic pump 33 and the relief valve 31 ensures that the load supported by the prime mover is maintained substantially constant. Any tendency towards a variation in the magnitude of the load supported by the prime mover is compensated for by appropriate pivotal movement of the compensating member 21.

The embodiment illustrated in Fig. 5 of the accompanying drawings is a variation to the embodiment described above. Referring to Fig. 5, the beam structure 23 is in this embodiment pivotally mounted at its rearward end onto the gooseneck 1 9. The hydraulic cylinders 29 are pivotally mounted between the gooseneck and a location (indicated by the reference numeral 37) intermediate of the ends of the beam structure. With this arrangement, the cylinders 29 undergo extension on pivotal movement of the beam structure relative to the gooseneck when the prime mover 11 moves upwardly relative to the trailer.

Likewise, the cylinders undergo retraction on pivotal movement of the beam structure rela tive to the gooseneck when the prime mover moves downwardly relative to the trailer.

In a further variation to the embodiment illustrated in Figs. 3 and 4 of the accompanying drawings, the hydraulic cylinders 29 are positioned between the rear end of the beam structure and the trailer rather than between the rear end of the beam structure and the gooseneck.

Referring now to the embodiment illustrated in Fig. 6 of the accompanying drawings, the coupling assembly 1 5 comprises a gooseneck 41 attached to the trailer 1 3 and a compensating member 21 coupling the gooseneck to the prime mover. In this embodiment the compensating member 21 comprises the fifth wheel 27 of the prime mover, the fifth wheel being mounted at a pivot 43 onto the prime mover for rotation about a horizontal axis generally transverse to the direction of travel of the prime mover-trailer combination. At least one hydraulic cylinder 29 is pivotally connected between the prime mover and the fifth wheel. Relative pivotal movement between the prime mover and the trailer effects pivotal movement between the compensating member 21 (the fifth wheel) and the prime mover.As with the previously described embodiments, the cylinder 29 extends or retracts to accommodate the relative pivotal movement within the cylinder being maintained substantially constant by the actions of the relief valve 31 and the pump 33. Any tendency towards a variation in the load supported by the prime mover as a result of variations in the level of the road surface is compensated for by appropriate pivotal move ment of the compensating member.

From the foregoing it is evident that a coupling assembly according to the invention is capable of compensating for variations in the level of the road surface and maintaining a substantially constant load on the prime mover.

It should be appreciated that the term "prescribed pressure" may be taken to mean a specific pressure or a pressure or a pressure range; in instances where the latter interpretation applies the pump 33 is adapted to commence the pumping cycle when the fluid pressure falls below the lowermost valve of the pressure range and the relief valve 31 is adapted to open when the fluid pressure ex creeds the uppermost valve of the pressure range.

Furthermore, it should be appreciated that the scope of the invention is not limited to the scope ot the particular embodiments de scribes'.

Claims (11)

1. An assembly for coupling a trailing vehicle to a prime mover comprising a gooseneck attached to the trailer, a compensating member coupling the gooseneck to the prime mover, and at least one hydraulic cylinder positioned between the compensating member and the gooseneck or the trailer of the prime mover whereby the load supported by the prime mover is maintained substantially constant.

2. An assembly as claimed in claim 1 wherein the compensating member is pivotally mounted on the gooseneck or the prime mover for rotation about a substantially horizontal axis generally transverse to the direction of travel of the prime mover-trailer combination.

3. An assembly as claimed in claim 2 wherein said at least one hydraulic cylinder is adapted to exert a substantially constant force on the compensating member the magnitude of which force is commensurate with the reaction force normally (as hereinbefore defined) applied to the compensating member to thereby maintain the compensating member in an equilibrium condition.

4. An assembly as claimed in any one of the preceding claims wherein hydraulic fluid is supplied to said at least one hydraulic cylinder by means of a hydraulic pump, the pump being adapted to supply hydraulic fluid to the cylinder at a prescribed pressure (as hereinbefore defined).

5. An assembly as claimed in claim 4 wherein the hydraulic pump operates continuously during operation of the prime movertrailer combination while only effecting fluid pumping when the fluid pressure falls below said prescribed pressure.

6. An assembly as claimed in any one of the preceding claims wherein there is provided a fluid pressure relief valve, the valve being adapted to open to release fluid pressure when the pressure in the at least one hydraulic cylinder exceeds said prescribed pressure.

7. An assembly as claimed in claim 4, 5 or 6 wherein there is provided means for selectively varying the magnitude of said pre scribed pressure.

8. An assembly as claimed in any one of the preceding claims wherein the compensating member comprises a beam structure.

9. An assembly as claimed in claim 8 wherein said beam structure is pivotally mounted on the gooseneck at a pivot intermediate the forward and rearward ends of the beam structure, the forward end of the beam structure being adapted for connection to the prime mover, said at least one hydraulic cylinder being pivotally connected between the gooseneck and the rearward end of the beam structure.

1 0. An assembly as claimed in claim 8 wherein saiq beam structure is pivotally mounted at its rearward end onto the gooseneck, the forward end of the beam structure being adapted for connection to the prime mover, said at least one hydraulic cylinder being pivotally connected between the gooseneck and a point intermediate the forward and rearward ends of the beam structure.

11. An assembly as claimed in any one of claims 1 to 7 wherein the compensating member comprises the fifth wheel of the prime mover, the fifth wheel being pivotally mounted on the prime manner so as to define said pivotal mounting of the compensating member on the prime mover for rotation about a substantially horizontal axis generally transverse to the direction of travel of the prime mover-trailer combination.

1 2. An assembly as claimed in claim 11 wherein said at least one hydraulic cylinder is pivotally connected berween the prime mover and the fifth wheel.

1 3. An assembly for coupling a trailing vehicle to a prime mover substantially as herein described and as shown in the accompanying drawings.