Trailer breakaway cable

[[159032]]

There should be an attachment point on the tow bar/ hitch for the chain or cable. https://www.caravanclub.co.uk/advice-and-training/technical-advice/breakaway-cables/

Unfortunately it isn't a legal requirement. But is a much more secure method.

 

[Refueler]

The chain shouldn't be on the ball hitch, it should be fixed to the vehicle.

Sorry but not correct ... please show how you will fix an endless chain to vehicle ?

Its designed to slip over the towball as a second back up.

I agree that usually in terms of back up you would look for a second strong point ... but here we are talking about cars with literally no chassis and only strong point is the towball itself !!

This aint no Land Rover !

 

[rogerthebodger]

And if the hitch comes off? And any connections should be as strong as the chain or cable.

WOW

My and most tow hitch is attached with 2 x M16 bolts with nyloc nuts. Whats the chance of these breaking. If they are in that bad condition you should not be allowed to tow anything above the skin off a rice pudding.

 

[Refueler]

There should be an attachment point on the tow bar/ hitch for the chain or cable. How to attach your breakaway cables

Unfortunately it isn't a legal requirement. But is a much more secure method.

Good link ... but it is showing the BRAKE breakaway cable .... not the back-up chain

 

[halcyon]

The ball hitch is attached to the vehicle. If you have hooks attaching the chain to the vehicle that adds a week link as the hooks could bend open releasing the trailer.

Back around 1970 I had to go to Strensham Service station to check the braking system on a new 6 Ton boat trailer with our undergear, it had crossed from the M5 southbound lane to the northbound and carried on going south till it ran out of momentum. The hitch had come off the towbar and was still attached to tow vehicle, so breakaway cable was still connected to car and coupling handbrake.

So never assume everything will work all the time, in the above case we did come up with a solution.

Brian

 

[rogerthebodger]

This is a 15 meter mast I towed from Johannesburg to Durban 600Km

I also towed an 18 meter mast on the same trailer from Cape Town to Johannesburg 1400 Km.

Both times the local stopped me and inspected the setup.

 

[Refueler]

Back around 1970 I had to go to Strensham Service station to check the braking system on a new 6 Ton boat trailer with our undergear, it had crossed from the M5 southbound lane to the northbound and carried on going south till it ran out of momentum. The hitch had come off the towbar and was still attached to tow vehicle, so breakaway cable was still connected to car and coupling handbrake.

So never assume everything will work all the time, in the above case we did come up with a solution.

Brian

Nothing is perfect ............ there's already a photo posted of a hitch that has broken off from trailer but still on the ball.

 

[prv]

So when the breakaway cable breaks what holds the brake lever in the on position.

The ratchet mechanism.

Pete

 

[[159032]]

If you leave the ratchet pawl in the active position the brakes will remain on after you have braked for a junction or any other reason.
Only applies to the older and now unavailable hitches.

 

[rogerthebodger]

The ratchet mechanism.

Pete

Hi Pete
The ratchet mechanism holds the hand brake on once parked and if the normal ratchet mechanism if the pawl was engaged it would keep the brake on at the first application of the overrun brake.

The breakaway would need a seperate different design ratchet mechanism to work with the breakaway cable. There isn't one on my car trailer overrun brake.

No handbrake and no breakaway ratchet.

Handbrake with ratchet in the off position normal when driving.

 

[Refueler]

The ratchet mechanism.

Pete

Great .... I see you don't tow many then !! At least none with the ratchet handbrake !

 

[prv]

There are clearly several different designs being discussed here.

Pete

 

[JumbleDuck]

My and most tow hitch is attached with 2 x M16 bolts with nyloc nuts. Whats the chance of these breaking.

Corroded tow hitches breaking at the "neck" below the ball is a well-established failure mode.

 

[[159032]]

There are clearly several different designs being discussed here.

There are two requirements.
Those for unbraked trailers and those for braked trailers The Law for Trailers.

​

Trailers should be fitted with 50mm ball coupling to ISO and BSI standards.
Unbraked trailers must have a stout secondary coupling, such as a chain, which is connected securely to the towing vehicle when it is being towed. The secondary coupling must be tight enough to prevent the trailer's tow hitch from hitting the ground if the vehicle becomes uncoupled.


Braked trailers must be fitted with hydraulically damped coupling and auto reverse brakes to give braking efficiencies required by EEC Directive 71/320. All wheels must be braked. Braked trailers must be fitted with a breakaway cable. This must be attached to the towing vehicle in such a manner so that, should the trailer become detached, the breakaway cable will operate the trailer's brakes. It is not advisable to connect the breakaway cable to the towball itself, unless it cannot be avoided. Most tow bars have either a drilled hole, or pigtail attachment, specifically intended to accept the breakaway cable's spring clip.

Braked trailers must be fitted with a parking brake that operates on at least two road wheels on the same axle.

Nigel's reference to a safety chain in addition to a breakaway cable on braked trailers is not a requirement. Indeed it could interfere with the operation of the brakes, if too short.

..

 

[duncan99210]

So when the breakaway cable breaks what holds the brake lever in the on position.

It there is nothing holding the trailer brakes on they will simply release and the trailer will carry on moving.

BTW crossing a safety chain stops the chain jumping off the tow ball hitch.

As I said, the appropriate brake actuating mechanism is required for the cable to operate the brake. The handbrake is a separate mechanism to the overrun brakes, albeit that they both work the same brakes. Once the handbrake is actuated, it locks in the on position until released. There’s a diagram here:
As you can see, if the hitch becomes disconnected and the trailer breaks away, the cable pulls on the bottom of the handbrake lever, locking the brakes on and stopping the trailer. The cable breaks as it does this, being a weak link in the system.

 

[rogerthebodger]

As I said, the appropriate brake actuating mechanism is required for the cable to operate the brake. The handbrake is a separate mechanism to the overrun brakes, albeit that they both work the same brakes. Once the handbrake is actuated, it locks in the on position until released. There’s a diagram here: View attachment 92371
As you can see, if the hitch becomes disconnected and the trailer breaks away, the cable pulls on the bottom of the handbrake lever, locking the brakes on and stopping the trailer. The cable breaks as it does this, being a weak link in the system.

I can see there is 2 seperate levers operating the brakes,one for the overrun and handbrake and a seperate one for the breakaway cable. but I still cannot see how the brake is held on after the cable has broken away.

Also this is quite a different design and with if the old type was fitted it would need replacing.

With the chain like we use it only requires the addition of a chain attached to the trailer also it makes a non braked trailer also safer. But each to his own

 

[halcyon]

I can see there is 2 seperate levers operating the brakes,one for the overrun and handbrake and a seperate one for the breakaway cable. but I still cannot see how the brake is held on after the cable has broken away.

Also this is quite a different design and with if the old type was fitted it would need replacing.

With the chain like we use it only requires the addition of a chain attached to the trailer also it makes a non braked trailer also safer. But each to his own

The handbrake applies a force to the overrun brake lever, breakaway cable pulls handbrake on.

Brian

 

[KREW2]

I can see there is 2 seperate levers operating the brakes,one for the overrun and handbrake and a seperate one for the breakaway cable. but I still cannot see how the brake is held on after the cable has broken away.
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If you want the handbrake to be effective after a decoupling you have to have an energy store.

Coupling Energy Stores - Towing and Trailers Ltd

 

[rogerthebodger]

The handbrake applies a force to the overrun brake lever, breakaway cable pulls handbrake on.

Brian

Yes Brian but what keeps the brake on once the breakaway cable has broken away.

It cannot be the handbrake which in my setup is also operated by the overrun coupling.

The last trailer I built in the UK must have been late 70's early 80's

 

[rogerthebodger]

I can see there is 2 seperate levers operating the brakes,one for the overrun and handbrake and a seperate one for the breakaway cable. but I still cannot see how the brake is held on after the cable has broken away.
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If you want the handbrake to be effective after a decoupling you have to have an energy store.

Coupling Energy Stores - Towing and Trailers Ltd

How does that Energy store work to keep the brakes locked once the breakaway cable has broken.