GB2305985A

GB2305985A - Trailer with brakes operated on breakaway from a towing vehicle

Info

Publication number: GB2305985A
Application number: GB9520154A
Authority: GB
Inventors: Philip Andrew Hanson
Original assignee: Bradley Doublelock Ltd
Current assignee: Bradley Doublelock Ltd
Priority date: 1995-10-03
Filing date: 1995-10-03
Publication date: 1997-04-23
Also published as: DE19640043A1; GB9520154D0

Description

2305985 TOWABLE VERICLE This invention relates to a towable vehicle and

particularly, although not exclusively, relates to a breakaway cable assembly for a towable vehicle, for example a trailer.

A trailer shown schematically in Figure 1 of the accompanying diagrammatic drawings may include wheels 2 having autoreversing brake assemblies 4 associated therewith. The assemblies 4 are coupled by means of cables 6, turnbuckle 8 and energy store 10 to a handbrake lever assembly 12. The energy store is provided to ensure that the brake assemblies are maintained in a braking condition (when required), even if the trailer is parked on a hill such that the brake assemblies adopt a collapsed state. The trailer is arranged to be secured by means of a coupling head 14 to a coupling ball 16 of a towing vehicle.

As a safety precaution, a breakaway cable 18 is secured at one end relative to the coupling ball 16 and at its opposite end to the handbrake lever assembly 12. In the event of the coupling head 14 (or other coupling elements of the trailer) failing, the breakaway cable is arranged to prevent the towing vehicle and trailer from separating and to act upon the handbrake assembly 12 thereby to cause the trailer brakes to be applied with a view to bringing the trailer to a safe stop.

European Patent Publication No. 0385040 (RTN) describes an autoreversing brake assembly which automatically adopts a collapsed (or reverse) mode when the brakes are locked even momentarily. Because the brakes always adopt a collapsed mode under braking conditions, no energy store is needed between the handbrake lever assembly and the brakes. However, a relatively large force must be provided in order to collapse the brakes (and thereby cause their application) when a towing vehicle is moving and, in the event that the brakes need to be applied due to a failure in the coupling of the towable vehicle, the force will need to be applied via a breakaway cable. There is a problem however in providing a suitable breakaway cable for a trailer with a high gross weight and a low empty weight. For example, if a light cable is used on a fully laden trailer, it may break before the brakes of the trailer are applied; and if a heavy cable is used on an unladen trailer, the f orce applied on the cable by the towing vehicle may be too low for the brakes to be applied.

It is an object of the present invention to address problems associated with known breakaway cable assemblies.

According to the invention, there is provided a brake assembly for a towable vehicle, the assembly including a brake operation means and a breakaway cable assembly, the breakaway cable assembly including a first part arranged to be secured relative to a towing vehicle, a second part arranged at a predetermined position relative to said brake operation means when said brake assembly is in a first pre-operative condition, and a first cable, wherein said breakaway cable assembly is operable in use between said f irst pre-operative condition, an operative second condition wherein said assembly applies a force to brake the towable vehicle and a third condition, wherein in each of said conditions said first cable extends between said first and second parts.

Suitably, said f irst, second and third conditions are different conditions of said breakaway cable assembly.

Said brake operation means may include a user- operable member, for example a handbrake, f or applying the brakes of the towable vehicle.

Preferably, in said first pre-operative condition substantially no force is applied to said breakaway cable assembly. Preferably, in said operative second condition, the brake assembly is arranged such that the towing vehicle applies a force to said breakaway cable assembly to brake the towable vehicle. Preferably, the breakaway cable assembly is arranged such that, in use, on application of a force which is greater than a predetermined force, said breakaway cable assembly moves between said second and third conditions.

Preferably, the assembly is arranged such that, when in said third condition, the breakaway cable assembly remains operatively connected to the towable vehicle. This ensures that, in use, even after a predetermined force has been applied to cause the breakaway cable assembly to move from its second condition to its third condition, the towable vehicle is not allowed to become detached from the towing vehicle.

In a first embodiment, said first cable and a second cable may extend between said first and second parts when the assembly is in its first pre-operative condition and its second operative condition. Said first cable preferably has a higher breaking strain than said second cable. Thus, preferably, the assembly is arranged such that on moving from said second condition to said third condition said second cable breaks whereas said first cable continues to extend between said f irst and second parts.

Said first cable is preferably longer than said second cable. Said first and second cables are preferably secured together at first and second spaced apart positions along their extent wherein the length of said f irst cable between said f irst and second positions is suitably greater than the length of said second cable therebetween. Said first cable is preferably arranged to define said first and second parts.

Preferably, in said first embodiment, said third condition represents a condition in which the brakes of the towable vehicle are applied in use.

In a second embodiment, said second part of said breakaway cable assembly may comprise a stop means. Said stop means is preferably spaced from a first end of said first cable. Said first end is preferably arranged to be secured relative to the brake operation means of the towable vehicle. Said stop means is preferably positioned between said f irst end of said f irst cable and a second end thereof which second end is arranged to be secured relative to the towing vehicle.

In said second embodiment, said first cable is preferably arranged to extend through an opening in said brake assembly or a part f ixed relative thereto. Said stop means is preferably arranged to restrict the passage of said first cable through said opening. Said stop means is preferably arranged so that it is unable to pass through said opening.

Said stop means is preferably arranged such that, in said third condition, said stop means is adjacent said opening and a coupling head of a coupling device of said towable vehicle is supported by said cable and thereby 5 prevented, in use, from contacting the ground. Preferably, in said second embodiment, said third condition represents a condition in which the brakes of the towable vehicle are not applied in use.

It should be noted that in said f irst and second embodiments, the towing and towable vehicles remain coupled together even in said third condition. Accordingly, the invention extends to a brake assembly for a towable vehicle including a breakaway cable assembly is which is arranged to extend between a towing vehicle and a towable vehicle and is operable between a second position in which the towing vehicle can apply a force via said breakaway cable assembly to brake the towable vehicle and a third position in which the towing vehicle cannot apply a force via said breakaway cable assembly to brake the towable vehicle but the towable vehicle can remain coupled to the towing vehicle via said breakaway cable assembly.

In a third embodiment, the breakaway cable assembly includes means for releasably securing the first cable to a brake means for example a brake lever, of the towable vehicle. Said assembly is preferably arranged such that said first cable is released from said brake means to take up said third condition when a force greater than a predetermined magnitude is applied to said first cable. Said breakaway cable assembly preferably includes catch means arranged to secure said first cable in position when in said first and second conditions but to allow release of said first cable on moving from said second condition to said third condition.

The invention extends to a towable vehicle which includes a brake assembly as described herein.

The invention extends to a towing vehicle and a towable vehicle incorporating a brake assembly as described herein.

The invention extends to a breakaway cable assembly Rer se for a towable vehicle, the assembly including a first part arranged to be secured relative to a towing vehicle and a second part arranged to be secured at a predetermined position relative to a brake operation means of a towable vehicle when said assembly is in a first preoperative condition, and first cable, wherein said assembly is operable in use between said first preoperative condition, an operative second condition in which said first cable can apply a force to brake the towable vehicle and a third condition, wherein in each of said conditions said first cable extends between the f irst and second parts.

The invention further extends to a method of manufacturing a towable vehicle including a brake assembly, the method using a breakaway cable assembly and comprising providing a first part of th e breakaway cable assembly such that it can be secured relative to a towing vehicle and securing a second part at a predetermined position relative to a brake operation means of the towable vehicle, wherein said breakaway cable assembly includes a first cable and means allowing the brake cable assembly to be operable between a first pre-operative condition, a second condition wherein a braking force can be applied to the towing vehicle and a third condition wherein in each condition said first cable extends between said first and second parts.

The invention further extends to a method of operating a brake assembly of a towable vehicle using a breakaway cable assembly having a first part secured relative to a towing vehicle, a second part secured relative to the towable vehicle and a first cable extending between said first and second parts, the method comprising braking the towable vehicle with the breakaway cable in a second condition and allowing the breakaway cable to adopt a third condition, wherein in both said second and third conditions said first cable extends between said first and second parts.

Specific embodiments of the invention will now be described by way of example, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 is a schematic representation of a trailer coupled to a tow ball of a towing vehicle; Figure 2 shows a breakaway cable assembly; Figure 3 shows another breakaway cable assembly secured between a tow ball and part of a handbrake assembly in a pre-operative condition; Figure 4 shows a pre-operative condition of another breakaway cable assembly secured to a part of a handbrake assembly; and Figure 5 shows a post-operative condition of the 35 arrangement of Figure 4.

In the figures the same or similar parts are annotated with the same reference numerals.

Referring to figure 2, a breakaway cable assembly 20 comprises a first length of a relatively light duty wire 22 and a second length of heavier duty wire 24.

Respective ends 26, 28 of the wire 22 are secured by means of respective crimped ferrules 30, 32 to the wire 24 so that the length of wire 24 between the ferrules 30, 32 is greater than the length of wire 22 between the ferrules.

Respective ends of wire 24 are folded back upon themselves and secured by respective crimped ferrules 34, 36 to define respective loops 38, 40. Loop 38 is arranged to fit over a tow ball 16 and loop 40 is engaged with a catch 42 which is arranged to releasably secure the assembly 20 to handbrake lever assembly 12.

The assembly 20 may be used with any type of trailer brake assembly but is particularly advantageously used in association with a trailer having an autoreversing brake assembly of the type described in European Patent Publication number 0385040 (RTN) referred to above.

If coupling 14 fails on an unladen trailer which includes breakaway cable assembly ZO, then the light wire 22 will initially apply a force on the handbrake lever assembly 12 so that the brakes are initially applied. The wire 22 is arranged to break after a short time, whereupon wire 24 will be put under tension and will then apply a force to apply the brakes. The driver of the towing vehicle will feel jerks as the wire 22 brakes and then breaks. When the trailer is unladen the force on the wire 24 may not be sufficient to break it which will, therefore, retain the trailer.

9 - on the other hand, if the coupling 14 fails on a fully laden trailer which includes breakaway cable assembly 20, then the light wire 22 will apply the brakes for a very short time before breaking, whereupon wire 24 will be put under tension and will then apply a force to apply the brakes. Again, the driver of the towing vehicle will feel jerks as the wire 22 initially brakes and then breaks and may quickly stop the towing vehicle. if, however, the driver continues, the wire 24 will subsequently break to release the trailer.

It should be appreciated that the two stage application of the trailer brakes serves to alert the driver of the towing vehicle to the existence of a problem (coupling failure) thereby allowing suitable action (stopping of the trailer) to be taken.

Referring to figure 3, coupling assembly 70 of the towable vehicle includes a body 72 from which coupling head 14 extends and on which handbrake lever assembly 12 is pivotably mounted. The body 72 is, however, provided with an aperture 74 in a downwardly extending part 76 which aperture 74 cooperates with brake cable assembly 78.

The brake cable assembly 78 includes a length of relatively strong cable 80. A sliding woggle 82 is provided towards one end of the cable, the woggle being arranged to adjust the size of a loop 84 which allows the cable to be retained on neck 85 of the coupling ball 16. A stress limit ring 87 is optionally provided at the other end of the cable, or alternatively the cable is formed into a simple loop, for fixing it relative to the handbrake lever assembly 12.

A stop member 86 is fixed on the cable 80 between the aperture 74 and handbrake lever assembly 12 and is sized so that it cannot pass through the aperture 74. The member 86 is so positioned on the cable 80 that the cable 80 can be moved a sufficient distance to cause handbrake lever assembly 12 to apply the brakes before stop member 86 contacts part 76 in which aperture 74 is defined.

If coupling 14 fails on a trailer including the arrangement of Figure 3, then cable 78 applies a force in the direction of arrow 66 which causes lever assembly 12 to pivot about pivot axis 42 thereby to apply the trailer brakes. After the brakes have been applied for a time, the stress limit ring 87 may brake. (If a stress limit ring 87 is not provided, then the cable is arranged to break by alternative means at a position between stop member 86 and the position of attachment of the cable on the assembly 12). In any event, the cable will be pulled further in the director of arrow 66 so that stop member 86 contact parts 76 in which aperture 74 is defined. Thus, after cable 80 has broken, the trailer is still secured relative to the towing vehicle by the length of cable 80 which extends between neck 85 and the part 76.

Referring now to the figure 4 and 5 embodiment, handbrake lever assembly 12 includes pins 40 (only one of which is shown in the figures) which are spaced apart in the direction of pivot axis 42 and are arranged to receive a breakaway cable 50 therebetween. The cable 50 carries a nipple 52 which prevents the wire being pulled away from its position between the pins when in the figure 4 position. Downwards movement of the wire 50 is prevented by means of an L-shaped catch 56 which is pivotally mounted at pivot point 58 and which includes a limb 60 which is positioned between pins 40 below the wire 50 when arranged as in figure 4.

If coupling 14 fails on a trailer including the arrangement of figures 4 and 5, then cable 50 applies a force in the direction of arrow 66 which causes lever assembly 12 to pivot about its pivot axis 42 thereby to apply the trailer brakes. When the assembly 12 has pivoted a predetermined distance so that it assumes the figure 4 position, the catch is opened as the cable applies a force to the catch thereby to cause it to pivot in an anti-clockwise direction about pivot point 58. Cable 50 then moves downwards and can become disengaged from the position between pins 40. Thus, ef f ectively, is when a predetermined force is applied via cable 50, the cable is automatically released. Thus, the cable initially brakes the trailer but does not break. Therefore, the cable is re-usable after its operation.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in t his specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and - 12 drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A brake assembly for a towable vehicle, the assembly including a brake operation means (12) and a breakaway 5 cable assembly (20; 78; 50), the breakaway cable assembly including a first part (38; 84) arranged to be secured relative to a towing vehicle, a second part (42; 87; 52) arranged at a predetermined position relative to said brake operation means when said brake assembly is in a first pre-operative condition, and a first cable (24; 80; 50), wherein said breakaway cable assembly is operable in use between said first pre- operative condition, an operative second condition wherein said assembly applies a force to brake the towable vehicle and a third condition, wherein in each of said conditions said first cable extends between said first and second parts.

2. An assembly according to claim 1, wherein said brake operation means includes a user-operable member (12) for applying the brakes of the towable vehicle.

3. An assembly according to claim 1 or claim 2, which is arranged in use such that in said first pre-operative condition substantially no force is applied to said breakaway cable assembly; and in said operative second condition, the brake assembly is arranged such that the towing vehicle applies a force to said breakaway cable assembly to brake the towable vehicle.

4. An assembly according to any preceding claim, which is arranged such that, in use, on application of a force which is greater than a predetermined force, said breakaway cable assembly moves between said second and third conditions.

00....

5. An assembly according to any preceding claims, arranged such that, when in said third condition, the breakaway cable assembly remains operatively connected to the towable vehicle.

6. An assembly according to any preceding claim, wherein said first cable (24) and a second cable (22) extends between said first (38) and second parts (42) when the assembly is in its first pre-operative condition and its 10 second operative condition and said first cable has a higher breaking strain than said second cable.

7. An assembly according to any preceding claim, wherein said first cable (24) is longer than said second cable (22).

8. An assembly according to any of claims 1 to5, wherein said second part of said breakaway cable assembly comprises a stop means (86) which is spaced from a first end (87) of said first cable (80).

9. An assembly according to claim 8, wherein said first cable (80) is arranged to extend through an opening (74) in said brake assembly or a part fixed relative thereto and said stop means (86) is arranged to restrict the passage of said first cable through said opening.

10. An assembly according to any of claims 1 to 5, which includes means (52; 40; 56) for releasably securing the 30 f irst cable (50) to a brake means (12) of the towable vehicle such that said first cable is released from said brake means to take up said third condition when a force greater than a predetermined magnitude is applied to said first cable.

11. An assembly according to claim 10, wherein said breakaway cable assembly includes catch means (56) arranged to secure said first cable (50) in position when in said first and second conditions but to allow release of said first cable on moving from said second condition to said third condition.

12. A towable vehicle which includes a brake assembly according to any of claims 1 to 11.

13. A towing vehicle and a towable vehicle incorporating a brake assembly according to any of claims 1 to 12.

14. A breakaway cable assembly per se for a towable vehicle, the assembly including a first part arranged to be secured relative to a towing vehicle and a second part arranged to be secured at a predetermined position relative to a brake operation means of a towable vehicle when said assembly is in a first pre-operative condition, and first cable, wherein said assembly is operable in use between said first pre-operative condition, an operative second condition in which said first cable can apply a force to brake the towable vehicle and a third condition, wherein in each of said conditions said first cable extends between the first and second parts.

15. A method of manufacturing a towable vehicle including a brake assembly, the method using a breakaway cable assembly and comprising providing a first part of the breakaway cable assembly such that it can be secured relative to a towing vehicle and securing a second part at a predetermined position relative to a brake operation means of the towable vehicle, wherein said breakaway cable assembly includes a first cable and means allowing the brake cable assembly to be operable between a first pre- operative condition, a second condition wherein a braking f orce can be applied to the towing vehicle and a third condition wherein in each condition said first cable extends between said first and second parts.

16. A method of operating a brake assembly of a towable vehicle using a breakaway cable assembly having a f irst part secured relative to a towing vehicle, a second part secured relative to the towable vehicle and a first cable extending between said first and second parts, the method comprising braking the towable vehicle with the breakaway cable in a second condition and allowing the breakaway cable to adopt a third condition, wherein in both said second and third conditions said first cable extend between said first and second parts.

17. An assembly substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.

18. A towable vehicle substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.

19. A method substantially as hereinbef ore described with reference to the accompanying diagrammatic drawings.

Amendments to the claims have been filed as follows CLAIMS 1. A brake assembly for a towable vehicle, the assembly including a brake operation means and a breakaway cable assembly, the breakaway cable assembly including a first part arranged to be secured relative to a towing vehicle, a second part arranged at a predetermined position relative to said brake operation means when said brake assembly is in a first pre-operative condition, and a first cable, wherein said breakaway cable assembly is operable in use between said first pre-operative condition, an operative second condition wherein said assembly applies a force to brake the towable vehicle and a third condition, wherein in each of said conditions said first cable extends between said first and second parts.

2. An assembly according to claim 1, wherein said brake operation means includes a user-operable member for applying the brakes of the towable vehicle.

4. An assembly according to any preceding claim, which is arranged such that, in use, on application of a force which is greater than a predetermined forcef said breakaway cable assembly moves between said second and third conditions.

- IR 5. An assembly according to any preceding claims, arranged such that, when in said third condition, the breakaway cable assembly remains operatively connected to the towable vehicle.

6. An assembly according to any preceding claim, wherein said first cable and a second cable extends between said first and second parts when the assembly is in its first pre-operative condition and its second operative condition and said first cable has a higher breaking strain than said second cable.

7. An assembly according to any preceding claim, wherein said first cable is longer than said second cable.

8. An assembly according to any of claims 1 to 5, wherein said second part of said breakaway cable assembly comprises a stop means which is spaced from a first end of said first cable.

9. An assembly according to claim 8, wherein said first cable is arranged to extend through an opening in said brake assembly or a part fixed relative thereto and said stop means is arranged to restrict the passage of said first cable through said opening.

10. An assembly according to any of claims 1 to 5, which includes means for releasably securing the first cable to a brake means of the towable vehicle such that said first cable is released from said brake means to take up said third condition when a force greater than a predetermined magnitude is applied to said first cable.

11. An assembly according to claim lo, wherein said breakaway cable assembly includes catch means arranged to 1C1 - secure said first cable in position when in said f irst and second conditions but to allow release of said f irst cable on moving from said second condition to said third condition.

14. A breakaway cable assembly per se f or a towable vehicle, the assembly including a first part arranged to be secured relative to a towing vehicle and a second part is arranged to be secured at a predetermined position relative to a brake operation means of a towable vehicle when said assembly is in a first pre- operative condition, and first cable, wherein said assembly is operable in use between said first pre-operative condition, an operative second condition in which said f irst cable can apply a force to brake the towable vehicle and a third condition, wherein in each of said conditions said first cable extends between the first and second parts.

15. A method of manufacturing a towable vehicle including a brake assembly, the method using a breakaway cable assembly and comprising providing a f irst part of the breakaway cable assembly such that it can be secured relative to a towing vehicle and securing a second part at a predetermined position relative to a brake operation means of the towable vehicle, wherein said breakaway cable assembly includes a f irst cable and means allowing the brake cable assembly to be operable between a first preoperative condition, a second condition wherein a braking force can be applied to the towing vehicle and a third - 20 condition wherein in each condition said first cable extends between said first and second parts.