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Old 15 September 2014, 14:26   #21
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Originally Posted by Landlockedpirate
I actually tried a 3.5T version from a firm somewhere near Southampton. Very very effective, load stopped easily and the trailer was rock solid even under a heavy right foot
RM Trailers?
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Old 15 September 2014, 15:30   #22
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RM Trailers?
It might have been, but it was nearly 20 years ago !

It was a fantastic piece of kit, just very complicated (compared to the usual over run arrangement) and when I realised I would never be able to buy a new car, that was the end of that.
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Old 16 September 2014, 05:55   #23
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They did a load for the military. Froggies had a few air braked ones, down in Poole. Solid bit of kit.

Another company that became victims of the EU type approval regs, so I was informed. Shame.
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Old 16 September 2014, 06:52   #24
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I may be wrong here and I am open to correction, but I think the whole idea of the 1950s tech overrun brake is that (lack of maintenance notwithstanding) it is pretty much guaranteed to work.

As soon as you introduce electrics through a connector you then instantly introduce a dozen or so potential failure modes - things like corroded terminals etc down to "I forgot to plug it in". - Lack of lights coz the hitcher-up-erer got distracted is dangerous enough, but could you imagine the fallout of a 3T trailer with no brakes? - or if you "failesafe" thwem the brakes banging on on the m'way as the connection fails?

Yes, you can engineer all this stuff out, but we would be wandering into deadman territory - we all know the dodgy trailers out there already - add a load of expensive tech and guess what.....



Also - we are moaning here about our simple mechanical systems failing 'coz they go swimming.... you can probably guess where that thought is going!
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Old 02 October 2014, 12:55   #25
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Electric brakes are not illegal in the UK, it's just that the methods for applying them are generally not allowed.

In the USA, a brake controller mounted in the cabin of the towing vehicle controls braking power on the trailer and also allows the trailer to be braked independently of the towing vehicle. There is normally a sensor in the towing vehicle to sense deceleration and transmit this information to the brake controller to apply the trailer brakes.

In the UK, legislation states that the trailer brakes must be capable of being applied without the driver removing their hands from the steering wheel. Also, the device used for measuring deceleration in order to determine the braking force required must be mounted on the trailer. The electrical power supply for the trailer braking system must be fed directly from the towing vehicle. If the trailer braking system has a battery, it must be disconnected while the brakes are being applied.

Some American trailers use a +12v signal from the brake light wiring in order to start the braking on the trailer. In the UK, braking force on all axles must reach the level required by legislation within 600ms of the driver applying the brakes in the towing vehicle and waiting for the signal from the lights may cause this time limit to be exceeded.

If a UK trailer is fitted with brakes, the brakes must be on all wheels. Also, regardless of which type of braking system it has, there must be a purely mechanical parking brake which is capable of holding the trailer on an 18% gradient.

Just as a side note, the Land Rover Defender can tow up to 4000kg if fitted with close coupled brakes. LRSV do an air brake system for just this purpose and I've seen an air brake converted Ifor Williams trailer before.

The reason why we are still using the mechanical overrun brake on our trailers is because it's foolproof and providing it is well maintained, it will always 'just work' and it's fail safe. It doesn't require any electrical interface with the vehicle, and the braking effort on the trailer is always proportional to that of the towing vehicle. Since it's purely mechanical it is not susceptible to electrical faults or failure. If you need to stop suddenly, jam the anchors on and the trailer does the same. If for some reason the trailer detaches or you're in an accident and the connection between the vehicle and trailer is lost, the breakaway cable fully applies the brakes on the trailer and it comes to a stop. Very simple.
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Old 03 October 2014, 02:49   #26
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Electric brakes are not illegal in the UK, it's just that the methods for applying them are generally not allowed.
Here in the USA we can have both electric or hydraulic brakes on a small trailer. Some are drum, and the rest are disk brakes.

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In the USA, a brake controller mounted in the cabin of the towing vehicle controls braking power on the trailer and also allows the trailer to be braked independently of the towing vehicle.
Yes for electric brakes, and it works very effectively. That is what all the livestock trailers I have used and own do. If the trailer gets in a skid you can blip the trailer brakes on to swing it back behind the tow vehicle. You can also adjust how much braking you want. It is the most common type of braking system for travel type RV trailers, and car trailers. Hydraulic surge brakes are more common for smaller trailers like typically used under boats.

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There is normally a sensor in the towing vehicle to sense deceleration and transmit this information to the brake controller to apply the trailer brakes.
That is all part of the brake controller. My favorite controller is a Tekonsha P3.
Tekonsha - P3

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In the UK, legislation states that the trailer brakes must be capable of being applied without the driver removing their hands from the steering wheel.
Which both the electric brakes or hydraulic surge brakes do as they are seamless, and require no input from the driver to function. The brake controller automatically applies the brakes on electric brakes, and the master cylinder mounted in the trailer dictates how much braking to apply to the trailer.

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Also, the device used for measuring deceleration in order to determine the braking force required must be mounted on the trailer.
The brake controller is mounted under the tow vehicles dash within easy access, or now they are often integrated into the tow vehicle. This only applies to electric brakes.

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The electrical power supply for the trailer braking system must be fed directly from the towing vehicle. If the trailer braking system has a battery, it must be disconnected while the brakes are being applied.
I haven't personally worked on a vehicle with electric trailer brakes and a battery system, but they do exist. Our livestock trailers do use the center power supply but it is completely independent of the braking system. I see no reason you couldn't be charging your trailer battery and using the brakes at the same time.


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Some American trailers use a +12v signal from the brake light wiring in order to start the braking on the trailer.
Not that I have ever seen. Not our farm equipment, nor any of my boat trailers.

The reverse light power feed is used to cut disk brakes loose while backing up, or it is next to impossible as they will lock up if pushing uphill. Disk equipped trailers also can use a piece of metal (Coins work) to manually disengaged the brakes.

Quote:
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In the UK, braking force on all axles must reach the level required by legislation within 600ms of the driver applying the brakes in the towing vehicle and waiting for the signal from the lights may cause this time limit to be exceeded.
Since we are talking boats here, lets just assume the USA hydraulic brake system is standard, at which point as soon as the master engages from the pressure in the trailer tongue pushing forward, the brakes are being applied. With that said, the electrical signal is probably 10 times faster.

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If a UK trailer is fitted with brakes, the brakes must be on all wheels. Also, regardless of which type of braking system it has, there must be a purely mechanical parking brake which is capable of holding the trailer on an 18% gradient.
We can put brakes on 2-6 wheels depending on how many wheels the trailer has. Our parking brakes are purely mechanical, and although I have never tested my rock on an 18% grade it does quite well on my steep driveway, and has reliably held my boat there for years. Otherwise my anchor has served duty to hold the boat trailer on a steep hill when I have needed to disconnect. I will agree a mechanical parking brake would be nice to have.

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Just as a side note, the Land Rover Defender can tow up to 4000kg if fitted with close coupled brakes. LRSV do an air brake system for just this purpose and I've seen an air brake converted Ifor Williams trailer before.
Most full size trucks 3/4ton+ here in the USA are rated to tow 12,000lbs (5443kg), no air brakes needed as that requires a different drivers license. Our trailer braking systems work very well without going to air brakes.

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The reason why we are still using the mechanical overrun brake on our trailers is because it's foolproof and providing it is well maintained, it will always 'just work' and it's fail safe.
As do hydraulic brakes or EVERY vehicle today wouldn't be on the road.

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It doesn't require any electrical interface with the vehicle, and the braking effort on the trailer is always proportional to that of the towing vehicle.
As are hydraulic trailer brakes 100% mechanical. The trailer tongue push against the ball is what sets the pressure applied.

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Since it's purely mechanical it is not susceptible to electrical faults or failure. If you need to stop suddenly, jam the anchors on and the trailer does the same.
Hydraulic does the same, and DISK brakes just happen to do it better than drum! Ever smoked a drum brake setup? I have pushed my K2500 Suburban to the limits towing on steep winding roads, and my disk boat trailer brakes did their share of the work stopping us without overheating. Disk brakes are where it is at

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If for some reason the trailer detaches or you're in an accident and the connection between the vehicle and trailer is lost, the breakaway cable fully applies the brakes on the trailer and it comes to a stop. Very simple.
Same with hydraulic brakes. Just make sure on both setups the cable for the brakes is in good shape.
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Old 03 October 2014, 05:37   #27
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Elxis Trailers in Greece do disc brakes. I had one for my Humber OP 6.3 and it was fantastic, no corrosion problems, easy to inspect and great braking, what more could you want. The trailer was beautifully manufactured also, with oval tubing and well galvanised. We need an importer in UK.

Don't know if it meets the DOT requirements though.
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Old 16 October 2014, 09:03   #28
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I'm sure there are reasons why the electrical supply must come from the vehicle during braking and not the trailers own battery, but I'm not the one who writes the legislation so I don't know.

There are 2 types of electrical interface socket used on vehicles in the UK, the old 12N and 12S sockets, and the newer European 13 pin socket. The 12N socket does the essential lighting - indicators, brake, tail lights and fog light. The 12S socket is normally fitted alongside the 12N socket, and it purely for caravans as it provides a feed for reversing light, battery charging, and fridge electric.

The European 13 pin socket combines the two in a much better designed socket, with a twist fit locking mechanism which is watertight. It's the defacto standard for caravans now and a lot of other trailers are using it too, for example I hired a car transporter a few months ago and it had the 13 pin system rather than 12N. The 13 pin socket does however have 1 pin which is currently unused, so this could be use for electric braking in the future.

The short of it all is there is no electric trailer braking in the UK. They've never been used here, everything is on overrun brakes. Yes some people import trailers from the USA (especially ones that come with boat purchases) but generally they'll either have the trailer fitted with an overrun mechanism or they'll buy a suitable American tow vehicle. I can't see there being a big switch over any time soon, personally I wouldn't mind but I think things are good the way they are now. The overrun brake has its drawbacks, but overall it's simple and it'll always "just work".
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Old 17 October 2014, 20:44   #29
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Yes some people import trailers from the USA (especially ones that come with boat purchases) but generally they'll either have the trailer fitted with an overrun mechanism or they'll buy a suitable American tow vehicle.
For a boat trailer with hydraulic disk brakes all you need is a ball to tow the boat and you can drive forward all day long. You can even backup as long as the trailer is not pushing on the tow vehicle. And with a 5 pin connector wired in, when the tow vehicle is put in reverse the solenoid is engaged so you can backup. Very easy to wire the vehicle. ANY VEHICLE rated to tow the weight can tow a USA boat trailer. The system is 100% mechanically engaged, and our braked trailers are required to have a breakaway engagement too. That way if the tow vehicle and trailer go two separate ways the trailer brakes are automatically engaged. This is separate of the chain/cables between the trailer and tow vehicle. The solenoid is only for backing up, everything else is mechanical utilizing hydraulics.

Trailer brake away cable shown below attached to top of master cylinder in tongue.


Electric brakes are generally used on larger trailers IE: camping trailers, livestock trailers etc, with the next step being air brakes on big rigs. Pretty much all small trailers are hydraulic surge brakes, if they have any brakes at all.
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Old 18 October 2014, 14:18   #30
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To add to Pete's description, if you're using a 4-wire plug, you can usually disable the trailer brakes by either flipping a lever or blocking the actuator. In the lever case, it usually resets as soon as pressure is released; I think the block has to be manually removed. Either one involves getting out and walking back to the trailer hitch, but it is still possible.

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