AU706555B2

AU706555B2 - Breakaway brake system for a vehicle trailer

Info

Publication number: AU706555B2
Application number: AU20055/95A
Authority: AU
Inventors: Wayne Kenneth Glew
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-05-13
Filing date: 1995-05-15
Publication date: 1999-06-17
Anticipated expiration: 2015-05-15
Also published as: AU2005595A

Description

2

TITLE

BREAKAWAY BRAKE SYSTEM FOR A VEHICLE

TRAILER

FIELD OF THE INVENTION The present invention relates to a breakaway brake system for a vehicle trailer particularly, although not exclusively, envisaged for use in applying the brakes of a trailer in the event that it becomes detached from its towing vehicle whilst travelling along.

In the context of the present invention "vehicle 10 trailers" means any trailer which is intended to be pulled by a vehicle and includes goods carrying trailers (such as the well known box trailers caravans, animal trailers S" (such as horse floats trailers for carrying vehicles (such as car trailers) and the like.

BACKGROUND OF THE INVENTION Each year in Australia about 7000 vehicle trailers become detached from their towing vehicles whilst travelling along. Once detached the vehicle trailers tend 2 to break the chains which attach the trailer to the towing vehicle and then career along the road out of control. This 9*9*99 S" is particularly dangerous since once the trailer is detached from the towing vehicle the brake system of the trailer becomes inoperative and so the trailer travels a relatively long distance before it comes to a halt.

I have found that this can be overcome simply and easily be using a system to apply the brakes of the trailer in the event the trailer inadvertently becomes detached from the towing vehicle.

SUMMARY OF THE INVENTION Therefore it is an object of the present invention to provide a breakaway brake system for a vehicle trailer for applying the brakes of the vehicle trailer in the event that the vehicle trailer becomes detached from a towing vehicle whilst in forward motion.

In accordance with one aspect of the present invention there is provided a breakaway brake system for a vehicle trailer having a brake system including a pivotable -2Abrake actuator which when pivoted activates the brake system to apply a braking force to the wheels of the vehicle trailer, the breakaway brake system including: a connecting member coupled to the brake actuator; a spring means operatively coupled to the connecting member and biased so as to cause the connecting member to pivot the brake actuator for activating the brake system when the biasing is released; a holding member for holding the spring means in S1: 0 the biased state; and, a trigger connected to the holding member arranged 555.

to cause the holding member to release the hold on the .spring means which in turn activates the trailer brake system when the vehicle trailer inadvertently becomes 15 detached from the towing vehicle whilst the towing vehicle is travelling along.

BRIEF DESCRIPTION OF THE DRAWINGS An exemplary embodiment of the present invention will now be described with reference to the accompanying 20 drawings in which:- Figure 1 is a side view of a breakaway brake system in accordance with the present invention; Figure 2 is a perspective view, seen from above, of a spring lever of the breakaway brake system of Figure 1; Figure 3 is a perspective view, seen from above, of a trip mechanism of the breakaway brake system of Figure 1; Figure 4 is a perspective view of a trigger cable of the breakaway brake system of Figure 1; and, Figure 5 is a perspective view, seen from above, of a connecting arm of the breakaway brake system of Figure 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(S)

In Figure 1 there is shown a breakaway system comprising a spring mechanism 12, a trip or trigger mechanism 14, a trigger cable 16 and a connecting arm 18.

3 As shown in Figure 2 the spring mechanism 12 is typically formed from a rod 19 of spring steel. The rod 19 is wound into an L-shape having one end 20 for attachment to a mounting plate 22, an elbow 24 located intermediate the length of the rod 19 and a free end 26 located remote from the end 20. The spring mechanism has a mounting eye 28 located at the end 20, a spring coil 30 located at the elbow 24, and a connecting eye 32 located proximate the free end 26. The rod 19 is attached to the mounting plate 22 by a bolt 34 attached through the mounting eye 28 and fixed in place by a nut (not shown). The mounting plate 22 is fixed to a drawbar 38 (see Figure 1) of a vehicle trailer. The spring mechanism 12 has a spring force of typically between 15 to 35 foot-pounds, such as, for 9* 9e 9 4 example, about 30 foot-pounds. I have discovered that if the force is significantly greater than about 35 foot-pounds the spring mechanism tends to damage the remainder of the breakaway brake system 10. Also, I have found that if the force is significantly less than about 15 foot-pounds the spring mechanism tends to be too weak to initiate operation of the braking system of the vehicle trailer whose purpose it is to activate. The rod 19 of the spring mechanism 12 is wound so that the angle between the ends 20 and 26 is less than about 900, such as about 300. Hence, when the spring mechanism 12 is in the position as shown in Figures 1 and 2 the spring coil spring mechanism 12 is partly unwound so as to provide a prebiasing force in the direction of arrow As shown in Figure 3 the trip mechanism 14 comprises a post 60, a bar 62, and a rod 64. The post 60 is disposed upwardly from the drawbar 38 (or from the mounting plate 22 of the spring mechanism 12) and is supported by a brace 66. An upper end of the post 60 has a pivot 68 which pivotably retains the bar 62 so that the bar 62 can pivot with respect to the post 60. The rod 64 is attached to the bar 62 intermediate the length of the bar 62 and substantially at 90' to the bar 62.

The rod 64 has a hook 70 located at its free end remote from the bar 62. The hook 70 is arranged to be located around the rod 19 between the elbow 24 and the free end 26 so as to bend the spring mechanism 12 against the returning force of the spring coil 30. The hook 70 is shaped to be able retain the rod 19 from returning to its unsprung position. The bar 62 also has a notch 72 located at its free end 74 remote from the pivot 68. The notch 72 is located in the same side 76 of the bar 62 as the rod 64. The notch 72 is disposed to receive the trigger cable 16.

As shown in Figure 4 the trigger cable 16 has two loops and 82, one located at each of its ends. The loop 80 is intended to be received in the notch 72 of the trigger mechanism 14 and the loop 82 is intended to be attached to the tow bar of the towing vehicle. The purpose of the trigger cable 16 is to cause the bar 62 of the trigger mechanism 14 to pivot about the pivot 68 to release the rod 19 from the hook in the event that the vehicle trailer becomes detached from 5 the towing vehicle. In the present embodiment the trigger cable 16 is designed to yield when the vehicle trailer becomes detached from the towing vehicle, after the hook 70 has released from the rod 19.

As shown in Figure 5 the connecting arm 18 comprises a pivot block 90, a sliding block 92 and a turnbuckle 94.

The pivot block 90 has a slot 96 at one end 98 with a hole 100 traversing the slot 96 for receiving a bolt 102 for pivotably attaching the connecting arm 18 to the connecting eye 32 of the spring mechanism 12 as shown in Figure 1. The slot 96 is dimensioned to receive the connecting eye 32 and to allow pivotable movement of the connecting eye 32 therein when the rod 19 pivots in the direction of the arrow The sliding block 92 has a hasp 110 with a slot 112 in each of its sides. The slot 112 is dimensioned to receive a bolt 114 which is fixed to a hand brake lever 120 of a towing assembly 122 of the vehicle trailer. The hasp 110 is dimensioned to allow pivoting of the hand brake lever 120 in the direction of arrow 124 when the spring mechanism 12 is set 20 in the position shown in Figure 1.

The turnbuckle 94 comprises a turning block 130, two threaded shafts 132 and 134, and two locking nuts 136 and 138.

The shaft 132 is threadedly engaged in a hole 140 in an end 142 of the pivot block 90 opposite from the end 98. The shaft 132 l 25 carries the nut 136 upon it for locking the shaft 132 in position in the hole 140. The shaft 134 is threadedly engaged in a hole (not shown) in an end 144 of the sliding block 92 The shaft 134 carries the locking nut 138 for locking the shaft 134 in position in the hole 140. The turning block 130 can be 30 rotated by a wrench or the like for adjusting the amount of threaded engagement of the shafts 132 and 134 in their respective blocks 90 and 92 (with the locking nuts 136 and 138 unthreaded from engagement with the ends 142 and 144 respectively. That is, the length of the connecting arm 18 can be altered by rotation of the turning block 130. This is required to adjust the breakaway brake system 10 for differing types of vehicle trailers.

In use, the mounting plate 22 is fixed to the drawbar 38 of the vehicle trailer and the post 60 of the trip mechanism 6 14 is fixed to the drawbar 38 (or to the mounting plate 22) with the hook 70 positioned for retaining the rod 19 of the spring mechanism 12 in the position shown in Figures 1 and 2.

The trigger cable 16 is then connected between the notch 72 of the bar 62 by the loop 80 and the drawbar of the towing vehicle by the loop 82. The connecting arm 18 is then attached to the rod 19 by the bolt 102 passed through the hole 100 in the pivot block 90 and through the connecting eye 32 of the rod 19. The sliding block 92 is then attached to the hand brake lever 120 of the towing assembly 122 by the bolt 114 passed through the slots 112 of the hasp 110 and a hole (not shown) in the hand brake lever 120. The turning block 130 is then rotated to adjust the length of the connecting arm 18 so suit the distance from the hand brake lever 120 to the rod 19 (when in its sprung loaded position).

When the vehicle trailer is in normal travel the breakaway brake system is in the position shown in Figure 1. In this position a push rod 150 of the towing assembly 122 is in its ~extended position. Accordingly, no brake fluid is pumped from a master brake cylinder 152 to slave brake cylinders (not shown) for braking the motion of the ground engaging wheels of the vehicle trailer.

When the vehicle trailer becomes inadvertently detached B from the towing vehicle whilst travelling along the trigger 25 cable 16 becomes taut and causes the bar 62 to pivot about the pivot 68. The pivoting causes the hook 70 to become disengaged from the rod 19. This allows the rod 19 to pivot under the return bias of the spring coil 30. The pivoting of the rod 19 causes the connecting arm 18 to move in the direction of arrow 30 160. The movement of the connecting arm 18 causes the hand brake lever 120 to pivot in the direction of the arrow 124.

The pivoting of the hand brake lever 120 causes the push rod 150 to be pushed into the master brake cylinder which causes brake fluid to be pumped to the slave cylinders which causes the brakes in the ground engaging wheels of the vehicle trailer to be applied for slowing the vehicle trailer to a stop.

The breakaway brake system 10 of the present invention has the advantage that the vehicle trailer is rapidly brought to a stop when it inadvertently becomes detached from its towing iKi~.

7 vehicle. In tests I have found that a vehicle trailer carrying a car at 100 kph will come to a stop within about 18m. Also, the breakaway brake system 10 causes the vehicle trailer to maintain a substantially straight line course as it slows to a stop.

It is envisaged that the breakaway brake system 10 could be applied to other forms of ground engaging wheel brake system of the vehicle trailer. For example, the breakaway brake system 10 could be applied to electric brakes or even manual brakes.

Also, it is envisaged that the breakaway brake system could have other forms of trip mechanism 14. For example, the trip mechanism 14 could be in the form a proximity sensor which detects then the vehicle trailer is greater than a predetermined distance form the towing vehicle and activates the brakes of the vehicle trailer accordingly.

In some situations the hand brake lever 120 operates in the opposite direction to the arrow 124. In these situations the spring mechanism 12 is arranged the opposite way around 20 from that shown in Figure 1.

Modifications and variations such as would be apparent to a skill addressee are considered within the scope of the present invention. For example, other forms of spring mechanism 12 could be used, such as, a tension spring. Also, 25 other forms of connecting arm 18 could be used provided that they allow movement of the hand brake lever 120 in the direction of the arrow 124 when the trailer hitch 166 causes actuation of the master cylinder (in known manner) and to cause the hand brake lever 120 to pivot in the direction of the arrow 30 124 when the spring mechanism 12 is triggered.

:30 124 when the spring mechanism 12 is triggered.

11 !111 8

The Claims defining the invention are as follows: i. A breakaway brake system for a vehicle trailer having a brake system including a pivotable brake actuator which when pivoted activates the brake system to apply a braking force to the wheels of the vehicle trailer, the breakaway brake system including: a connecting member coupled to the brake *actuator; 10 a spring means operatively coupled to the .connecting member and biased so as to cause the connecting member to pivot the brake actuator for activating the brake ":system when the biasing is released; a holding member for holding the spring means in 15 the biased state; and, Se *a trigger connected to the holding member arranged to cause the holding member to release the hold on the spring means which in turn activates the trailer brake system when the vehicle trailer inadvertently becomes 20 detached from the towing vehicle whilst the towing vehicle e o is travelling along.

2. A breakaway brake system for retrofitting to a vehicle trailer having a brake system including a manually activatable pivoting brake lever which when pivoted activates the brake system to apply a braking force to the wheels of the vehicle trailer, the breakaway brake system including: a connecting member coupled to the brake lever; a spring means operatively coupled to the connecting member and biased so as to cause the connecting member to pivot the brake lever for activating the brake system when the biasing is released; a holding member for holding the spring means in the biased state; and, a trigger connected to the holding member Sarranged to cause the holding member to release the hold on

Claims

3. A breakaway brake system according to either claim 1 or 2, in which the trigger is a cable connected i between the holding member and the towing vehicle so that when the trailer detached the cable is pulled taught exerting a pulling force on the holding member causing the 10 holding member to release and hold the spring means. 00*0 *0*0
4. A breakaway brake system according to claim 3, in which the holding member is a bar pivotable under the action of a pulling force from the cable, and the bar having a hook means for engaging with the spring means for S ee 15 holding it in the biased state and for releasing the spring o0 means when the cable pulls on the bar. S..
5. A breakaway brake system according to any one of o claims 1 to 4, wherein the connecting member is adjustable in length so that the breakaway brake system may be installed on vehicle trailers where the type and position of the brake actuator or lever varies from trailer to trailer.
6. A breakaway brake system for a vehicle trailer having a brake system including a brake actuation means for applying a braking force to the wheels of the vehicle trailer, the breakaway brake system being substantially as herein described with reference to and as illustrated in any one or more of the accompanying drawings. Dated this 15th day of April
1999. WAYNE KENNETH GLEW By His Patent Attorneys: GRIFFITH HACK Fellows Institute of Patent and Trade Mark R .Attorneys of Australia A ABSTRACT A breakaway brake system (10) for a vehicle trailer for applying the brakes of the vehicle trailer in the event that the vehicle trailer inadvertently becomes detached from a towing vehicle whilst in forward motion. The breakaway brake system (10) has a spring mechanism (12) triggerable by a trigger cable (16) for applying force to a hand brake lever (120) when the trigger cable (16) operates a trip mechanism (14). S e e*