OT - breakaway cables for braked trailers

[David.WE.Roberts]

The breakaway cable for my 2 ton twin axle braked trailer is looking a bit worn so I am replacing it.

This cable is quite substantial - 3mm diameter metal core covered in plastic.

All the cables in the shops are either 2mm or 3mm including the plastic, and much more flimsy.

Anyway, after some Googling I read that the cable is supposed to snatch the brake on then part.

Sensible, as if the trailer detaches at 60mph you don't want 2 tons of trailer trying to stop itself and your towing vehicle.

Now I've had a couple of 'pop offs' where I've carelessly not made sure the tow ball is fully locked on and the trailer has popped off as I started off.

In both cases the trailer braked, and the cable also stopped the car (which was only moving very slowly).

However the cable didn't part.

I am assuming that a greater strain would open up the clip holding the wire to the trailer brake.

I think a more flimsy replacement would just snap.

What I didn't see was any advice (which should be obvious once you know the cable is designed to part) that you should always carry at least one spare cable.

Otherwise if you snap your cable but the trailer (or caravan) survives then you cannot legally resume towing.

Cheers

Dave R

[Tim+]

You worry too much. Sheesh, do you carry spares for every bulb on your car?

Tim

[Tim Watts]

On Saturday 20 July 2013 20:26 Tim+ wrote in uk.d-i-y:

I do. Takes up sod all space.

[Dave Liquorice]

survives

I'd be more worried about the two tonnes of trailer doing 60 mph unbraked and on it's own rather than being within the law...

[Tim+]

And are you sure you have the tools to do a roadside repair? Some modern cars are an absolute bugger to change bulbs on.

Tim

[Grimly Curmudgeon]

In the event of the cable breaking I'd just put the boot down and get where I'm going in a hurry, so as to not spend too much time with an unbraked trailer on the car.

[Dave Liquorice]

Er, if the breakaway cable has bust it means the trailer has parted company from the towing vehicle. Like the OP said it's there to yank the brakes on and then part should the hitch fail for any reason.

Assuming the trailer survives dropping off you could just hitch it back up and carry on, it would still be braked for normal driving as that is done via a mechanism in the drawbar. What you wouldn't have is the brakes applied should the trailer part company again. This is when you have two tonnes of unbraked trailer on the loose, it's going to keep going until it either hits something or trys to do a tron 90 degree turn and flips. Either way it's going to be messy.

[Grimly Curmudgeon]

Exactly; so gtf out of there as quick as possible.

[Roger Mills]

I think that if the car and trailer part company at any speed, you're likely to end up with at least some damage which may make resuming towing difficult or impossible anyway.

I would err on the side of a heftier cable. I would rather have the cable *not* break than have it break *before* it had fully applied the trailer brakes.

I only ever broke one - and that was when I forgot to disconnect it after unhitching my caravan! The caravan brake was already fully applied (manually) so the cable didn't need to do this. It snapped very easily when I drove off - I didn't feel any resistance through the seat of my pants - so I worried a bit about whether it would have done the business if I'd had a real disconnect.

[Tim+]

Did it actually snap? I seem to recall that they all have a hefty split ring that is designed to unbend and open after the trailer brakes have been pulled on. The cable itself doesn't normally break.

Here's a typical one.

I know that when we dropped a van off the hook the ring "unwound" releasing the cable before it snapped.

Tim

[Scott M]

I've never been able to square break away cables with the idea that a trailer travelling at speed is going to dig its hitch in and flip/slew/explode almost immediately!

Broke one once - forgot to unhitch it after unhitching the trailer, d'oh - and heard it as a vague pwang sound. It worked as intended and then broke at the handbrake end. I simply shortened the cable a bit - must have crimped a new end on or similar.

[David.WE.Roberts]

Many and varied are the cables of breakaway :-)

I bought

as a spare - I intend to order something more meaty as a replacement.

This one has a snap hook on both ends so something apart from the fixings will need to part.

I suspect the cable will pull out of the metal grip used to make the loop onto the hook.

Even if it straightens out the ring on your example, at a minimum you would have to carry a spare ring.

Trailer supplier recommends the AL-KO cable part way down this page which looks quite close to the one I have, with the hook fixing to the brake.

I suspect most time the cable gets used is just after hitching or unhitching - so low speed incidents.

Still musing on why there isn't a prominent notice with these which says "Always carry a spare" or similar.

It could almost double the sales of the cables (for a short while).

Cheers

Dave R

[Roger Mills]

Oh yes, the cable itself snapped. The split ring was totally unaffected. It was hefty enough not to be opened up by any force the cable could exert on it before breaking.

[Jim K]

do multi axle trailers do that?

Jim K

[dennis]

When I had a trailer tent with brakes I used a thick cable with the intention that it wouldn't break.

I reasoned that I would still be able to bring it to a controlled stop if I let it do the braking.

My current un-braked trailer came with a fixed chain to keep the thing attached to the car if it came unhitched. Its probably a good idea, a new bumper is better than having it go somewhere bad.

[bert]

If yo mean closed coupled twin axle properly loaded then they tend to be more stable (or less unstable) in both pitch and yaw. There is a damping effect through the suspension. Single axle trailers are inherently unstable.