Trailer breakaway cable

KREW2 said:
If you have auto reverse brake drums it is essential that you fit an energy store. Without it your handbrake will not work if the trailer is parked on a slope, with the rear of the trailer facing down the incline.
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My handbrake works on a slope.

It also can be reversed up a moderate slope as well.

Perhaps caravan setups are different but I'm quite satisfied that should the coupling fail then the 1.5 ton caravan will come to a "safe" as can be stop on the road.....

I certainly don't want it attached to the rear of my vehicle!!!
 
My worry is that a caravan or maybe a 3 ton boat can breakaway from the towing vehicle at 50 mph and we can be confident that it will stop in a straight line with the a-frame ploughing the road and the two (or four), infrequently serviced (and who thinks to balance the brakes?) braked wheels trying to stop the whole kit before it veers over into the oncoming traffic.

I know a guy who was severely injured when a wagon's trailer did just that and ploughed into his car. That could be a closing impact of 100 mph.
 
The stopping distance for a car doing 50mph would be around 120 to 125 ft. This from a stopping distance calculator.

If we consider a trailer with its brakes applied by the breakaway cable is about the same.

The hitch disconnecting from the car and once the breakaway cable has detach the hitch would hit the road and cause extra friction which would tend to cause the trailer to jack knife and the momentum of the trailer load and the friction of the scrubbing tyres would tend to cause the trailer to tip over and now is just sliding along the road on its side.

The trailer is now totally out of control and could go anywhere.

Any slight difference in the braking force of the brakes would cause the trailer to vier one way or the other making it more possible to jack knife nd tip over.
 
I think the overwhelming priority has to be keeping the trailer attached to the car. Breakaway cables and automatic brakes are all very well, but as Rogershaw suggests, the best you can hope for them is a modest reduction in the scale of the disaster.
 
Refueler said:
Total poppycock ! Please explain how all those 1980 's caravans with auto reverse brakes were successfully handbraked like mine ?

The handbrake when put on with trailer stopped .. means the brake shoes move out to braked without the auto reverse mechanisn having flipped over. The auto reverse can only activate when brake is NOT on and is why you have to start moving back so slow - to avoid putting the brake on ... then it flips and you can then reverse - STILL slowly.
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Never owned a caravan, so can't comment on them.
Don't know what you mean by flipped over. What is the point of auto reverse brakes if they lock on.

As the trailer is reversed the tow hitch activates the brakes, as the wheels turn backwards the pads collapse away from the drums allowing the wheel to turn backwards. On a slope the wheels will be trying to go backwards.
I still don't trust the auto system on a slope even with an energy store, and prefer to park facing downhill.
Our four wheeled braked trailer can't be pushed forward with the handbrake on, but can still be pushed backwards on the flat.
 
KREW2 said:
Never owned a caravan, so can't comment on them.
Don't know what you mean by flipped over. What is the point of auto reverse brakes if they lock on.

As the trailer is reversed the tow hitch activates the brakes, as the wheels turn backwards the pads collapse away from the drums allowing the wheel to turn backwards. On a slope the wheels will be trying to go backwards.
I still don't trust the auto system on a slope even with an energy store, and prefer to park facing downhill.
Our four wheeled braked trailer can't be pushed forward with the handbrake on, but can still be pushed backwards on the flat.
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What you are ignoring is the over-run function .... if you start to reverse - you will push the hitch shaft back which then presses on the handbrake lever as in OP's photo.
The auto-reverse allows you to reverse but slowly so that in my words - the system can flip to allow wheels to turn backward .. and even with shaft pressing on handbrake - brakes do not come on.
BUT with van / trailer stationary - applying the handbrake locks the wheels as shoes etc are in braking normal position.

I had caravan with this and apart from the odd time I was a little quick on starting to reverse .. handbrake and auto reverse worked fine. Handbrake always reliable in fact.
 
JumbleDuck said:
I think the overwhelming priority has to be keeping the trailer attached to the car. Breakaway cables and automatic brakes are all very well, but as Rogershaw suggests, the best you can hope for them is a modest reduction in the scale of the disaster.
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I have to admit that I was always a little worried about hitches and the backups ... it all seemed to be a bit of a lash up.

Chain that in event of a full loaded trailer would possibly break with the sudden load.

Breakaway cables without augmented system to lock brakes on
 
I think we are roughly on the same hymn sheet.
The handbrake needs to be on tight, so good adjustment is paramount. On a downward slope the energy store makes sure that the handbrake lever is tightly cranked on.
However I still don't trust auto reverse on a slope.
 
KREW2 said:
I think we are roughly on the same hymn sheet.
The handbrake needs to be on tight, so good adjustment is paramount. On a downward slope the energy store makes sure that the handbrake lever is tightly cranked on.
However I still don't trust auto reverse on a slope.
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As I understand it - auto reverse is pretty standard now on caravans at least .. and when do you park a van on a slope ... don't you put the 'legs' down and level up ? I also had chocks as a back up ... not because my brakes were faulty - they were excellent in fact - but as security.
Legs + handbrake means pretty solid stay put !! Chocks and she aint gonna go anywhere !
 
First observation from the original photo- the slot that the handbrake lever moves in looks a little short for the travel required.
Second, I had one of these hitches on a Sinclair horsebox many years ago- the breakaway cable runs under the hitch and round a guide at the rear of the hitch, then up above the hitch and onto a triangular pivot free to rotate on the handbrake lever. This plate acts as a cam holding the ratchet lever clear of the rack in normal driving, but when the breakaway cable is pulled the cable rotates the cam to allow the ratchet to fall on the rack. Continued pulling then tightens the brake, which the ratchet holds on. When fully applied, the cable then breaks.
Reversing was as described above, the flip over plate at the hitch.
Brian should remember this from Sinclair trailers!
 
Hot Property said:
My handbrake works on a slope.

It also can be reversed up a moderate slope as well.
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Which furthers my point.
Reversing up a slope should push the brakes on harder, not too different to applying the hand brake, but still the wheels are free to move backwards.
I have only worked on two trailers with The Knott Auto systems, but striped them down several times.
I know how they work, what baffles me is why it works.
 
KREW2 said:
Which furthers my point.
Reversing up a slope should push the brakes on harder, not too different to applying the hand brake, but still the wheels are free to move backwards.
I have only worked on two trailers with The Knott Auto systems, but striped them down several times.
I know how they work, what baffles me is why it works.
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The basic principle, as far as I can see, is that the braking system disengages if the wheels rotate backwards. It may be that applying the handbrake before the wheels move applies the brakes in a way which can't be overridden, but I know that when my Drascombe trailer is moving backwards down the slipway the handbrake (nice new Knott hubs) has no effect whatsoever.
 
JumbleDuck said:
The basic principle, as far as I can see, is that the braking system disengages if the wheels rotate backwards. It may be that applying the handbrake before the wheels move applies the brakes in a way which can't be overridden, but I know that when my Drascombe trailer is moving backwards down the slipway the handbrake (nice new Knott hubs) has no effect whatsoever.
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Here are the instructions for using the handbrake on Knott auto reverse braking system.
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All Indespension couplings are fitted with spring loaded handbrake systems which, upon application of the handbrake automatically apply further pressure should the trailer roll backwards. The system ensure adequate force is applied to the brakes.
Many manufacturers now use this type of handbrake system as it self controls the forces going from the handbrake spring energy store into the brakes once the handbrake has been applied.
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There is also a full explanation on their website as to how and energy store is essential for the hand brake to be properly effective.
 
JumbleDuck said:
The basic principle, as far as I can see, is that the braking system disengages if the wheels rotate backwards. It may be that applying the handbrake before the wheels move applies the brakes in a way which can't be overridden, but I know that when my Drascombe trailer is moving backwards down the slipway the handbrake (nice new Knott hubs) has no effect whatsoever.
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As you correctly surmise - and is what I found with my auto-reverse trailers ... as long as you applied handbrake when stopped OR moving forward - it locked perfectly.
But if you tried when trailer was moving backwards - its too late as the auto reverse has actioned.
 
Refueler said:
As you correctly surmise - and is what I found with my auto-reverse trailers ... as long as you applied handbrake when stopped OR moving forward - it locked perfectly.
But if you tried when trailer was moving backwards - its too late as the auto reverse has actioned.
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Firstly apologies to the OP for a bit of thread drift.
Here his a description of how the system workshttp://www.indespension.co.uk/blog/post/356
 
KREW2 said:
There is also a full explanation on their website as to how and energy store is essential for the hand brake to be properly effective.
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Refueler said:
As you correctly surmise - and is what I found with my auto-reverse trailers ... as long as you applied handbrake when stopped OR moving forward - it locked perfectly.
But if you tried when trailer was moving backwards - its too late as the auto reverse has actioned.
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Thanks, both. Sounds as if I need to investigate fitting a springy thingy to the trailer.
 
JumbleDuck said:
Thanks, both. Sounds as if I need to investigate fitting a springy thingy to the trailer.
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Only if you want to park backwards on a slope, or insure against the unlikely event of it becoming decoupled going up hill.
As the trailer wheels start to roll back more pressure is applied by the energy store to hold the trailer.
However if the adjustment isn't spot on, as the instructions say, you can run out of energy, and it will roll back.
I don't do much road trailing now, I just move our club boats around our park. Our four wheel trailer has auto reverse, but no energy store, even if it did I would not trust it.
 
JumbleDuck said:
Thanks, both. Sounds as if I need to investigate fitting a springy thingy to the trailer.
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Only if you are worried that trailer is going to come unhitched when towing .... if its for parking - totally unnecessary.

If you watch the video earlier linked by another - it only operates when Handbrake is OVER centre ...

If you watch carefully the geometry of the handbrake pivot to energy store etc. - you will note that by hand, handbrake hits max brake - then he pushes more on lever to OVER-CENTRE it which then brings in the final action of the energy store unit.

This shows clearly that the energy store does not actually increase brake pressure .. it only locks it on.
 
KREW2 said:
Only if you want to park backwards on a slope, or insure against the unlikely event of it becoming decoupled going up hill.
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Refueler said:
Only if you are worried that trailer is going to come unhitched when towing .... if its for parking - totally unnecessary.
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Would it allow me to use the handbrake to stop, if not control, the trailer when backing it down a launching ramp by hand? If not, no point at all.
 
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