 | Home > Technical > 4000kg towing on coupled/air brakes, trailer types etc |
 
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| excossack Member Since: 22 Feb 2012 Location: North West Posts: 5736   
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A quick google led me to
https://forums.lr4x4.com/topic/46853-trail...-defender/ or https://www.lrukforums.com/threads/air-coupled-brakes.114989/ if any help ? 1999 Defender TD5 110 Regards John M0VAZ Econet Station 48 no clock |
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6th Jul 2020 8:36am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16857 
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I'm not an authority on the subject however it has always been my understanding that electric trailer brakes are not legal in the UK (shame really since there are several advantages), so air or vacuum is the only way to go. It is generally easier to compress air than decompress it, so I would suggest air as the way to go. I believe also that the trailer will have to come to a stop if it detaches, so you'd either need an air reservoir on the trailer or go down the spring brake route.
Don't forget also that 3.5t gross is the heaviest you can tow on a ball, so you will need a ring/pin or pintle/lunette coupling. It would be interesting to hear how you get on with this, please keep us updated. |
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6th Jul 2020 8:44am |
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| Bluest Member Since: 23 Apr 2016 Location: Lancashire Posts: 3995 
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There is some information pertaining to electric brakes here...
https://www.gov.uk/government/publications...egulations 2007 110 TDCi Station Wagon XS |
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6th Jul 2020 9:51am |
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| Matt110 Member Since: 29 Jun 2014 Location: UK Posts: 673
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Thanks both, the plan was to tow on a ring for the simple reason that it'll give articulation off-road. (not suggesting 4.0T offroad is a good plan for a minute but it's an engineering hobby exercise.... literally nothing is sensible!!)
I'm interested in the electric brakes bit because i can't currently find any actual words anywhere that forbid their use (assuming they're IVA'd). Have a look at this one.... https://www.gov.uk/government/publications...4-trailers That's the trailer IVA guide. Inside is the braking requirements.... now a couple of points: with electric brakes you don't get a brake-away "cable", but if the trailer disconnects from the vehicle the trailer brake will apply regardless. So you don't need the cable. A trailer on air brakes also wouldn't have a cable to engage the brakes on separation of the hitch.... it's the breaking of the air line that turns the brakes on. The electric cable is the same. Break the cable, brakes come on. So the requirements here can't mean that a break-away cable is REQUIRED, just that the functionality is present. (Otherwise the air brake kits sold for 4t (defenders - amongst other things) would also not be legal. In essence, the easiest way of doing this given there are parts available in Australia to just bolt on, is with electric brakes certified at that mass. Thus the reason for trying to bottom it out.  Click image to enlarge |
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6th Jul 2020 9:53am |
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| Matt110 Member Since: 29 Jun 2014 Location: UK Posts: 673
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Great find, thanks Bluest. Exerpt:
Suggests it's possible to fit electric braking with the module contained in the trailer. I might need to research how electric braked trailers do parking brake functionality as that's clearly the next problem. The Aussie trailer brakes appear to use a trailer brake control module in the cab, which controls the trailer brakes based on towing vehicle deceleration, but wouldn't be legal in EU as that would need to be mounted on the trailer itself. The link appears to then go into some very dry detail... which will require both a cup of tea AND a biscuit or two to get through. I shall have a read. https://eur-lex.europa.eu/LexUriServ/LexUr...101:en:PDF |
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6th Jul 2020 10:32am |
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| sako243 Member Since: 08 Jul 2014 Location: Wales Posts: 1185  
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Why on earth would you think 4t is not a good idea? Think these are a little more than 4t, admittedly the tyres are a bit bigger and there's a few more ponies under the bonnet 
Click image to enlarge Ed 82 Hotspur Sandringham 6x6 95 Defender 110 300Tdi |
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7th Jul 2020 4:12pm |
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| Matt110 Member Since: 29 Jun 2014 Location: UK Posts: 673
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Haha,
 now that's something I'd dearly love to be involved with instead of the daily 9-5!
The Aussie rigs seem to be towing vast weights off-road.... But with slightly more torque from a Toyota diesel V8! Patriot campers toy hauler looks amazing. |
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7th Jul 2020 5:54pm |
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| Hufflepuff Member Since: 25 Oct 2014 Location: Hampshire Posts: 723  
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They seem to be very concerned over GVM in Australia. Perhaps with all the overlanding they do they are regularly above the truck specs, and the Police are pretty hot on it?
I wouldn't even know what the GVM of a Defender is. 2005 Td5 90 XS 1989 V8 110 CSW |
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7th Jul 2020 6:15pm |
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| sako243 Member Since: 08 Jul 2014 Location: Wales Posts: 1185
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GVM depends a bit on what you've got... If you've got an older Defender (pre Td5ish) then all bets are off. Station wagons were 3050kg rather than 3450kg, most can tow 3.5t though but some are plated to 4t with coupled brakes.
I think 6x6 I've got is 3950kg on the vehicle itself but then with another 3950kg behind it (irrespective of coupled brakes I think). How on earth that sits with EU towing legislation or licenses I haven't got a clue - but the vehicle is plated for it. I will tell you that it will quite happily lock up all 6 wheels on the tarmac if you hit the brakes moderately hard. Probably something to do with the fact that it's got 6 of Land Rover's biggest brake drums. Both front brakes are dual piston and oversized ones as fitted to the Stage 1 V8s and then the rears get Stage 1 V8 drums on both axles. Ed 82 Hotspur Sandringham 6x6 95 Defender 110 300Tdi |
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7th Jul 2020 8:55pm |
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| Tommybahama32 Member Since: 11 Sep 2017 Location: cheshire Posts: 31 
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Hi, many years ago I worked in the BBC transport department. We used 110 Defenders to tow Cabmobile caravans for location filming work. These trailers weighed 3.5t empty. I was told that these Landrovers could tow 4.5 t because the had been converted to a vacumn braking system. I seem to remember a large low slung vacumn tank along the sill. I think the company who did the conversion were called Feeney and Johnson. The brakes worked well but towing at that weight at anything over 40 mph was scary stuff.
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8th Jul 2020 10:20am |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3346 
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The idea with most trailer brakes is that it requires input from the towing vehicle to hold the brakes off.
The default setting is that the brakes come on. On modern trailers the air pressure uses a piston to overcome a spring. When you apply the brakes the air is released and the spring applies the brakes, this is why they go PSHHHaw when you put the handbrake on. For smaller vehicles they used a vacuum which did the same thing but in reverse, it pulled a vaccum which held the brakes off and when you applied the brakes it allowed air into the system which allowed the springs to reapply the brakes. The idea being that if the trailer detaches no matter what happens the brakes will come on on the trailer and it will stop. Electronic brakes are a grey area because they are set to release as defult. When you apply a brake it energises a magnet which pulls the brakes on, instead of a piston or rod like in traditional overrun brakes. Where the problem lies is that a conventional system will be activated in the event of a breakaway, the breakaway cable will yank the handbrake on full which will lock in the brakes. An electronic brake system in the event of a breakaway relys on A. The system recognising it has broken away ether by loss of signal or current. B having enough energy in the system to apply the brakes hard long enough to stop the trailer and then keep it at rest. If it brakes away on a hill you don't want it rolling down that hill uncontrolled. I have seen a TDI with coupled vacuum brakes, I was considering it for my own TDI but decided that the very few occasions I would need to move something that heavy It would be cheaper and easier to hire a 7.5 ton lorry and just use that. Fascinating idea though I'm watching with keen interest! Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197 Self confessed mileage hunter |
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9th Jul 2020 9:56am |
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| Matt110 Member Since: 29 Jun 2014 Location: UK Posts: 673
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Just had a thought reading the replies above, does anyone have a plate on a defender that specifically indicates 4.0T with a "next level or category" of braking? Or is it in the type approval for the actual vehicle itself.
I've not got mine with me at the minute but i'm pondering if we solved all of this and you were stopped, how would the nice policeman know that the vehicle was plated to 4.0T with said brakes if it's not plated somewhere? |
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9th Jul 2020 10:13am |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3346
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The one I was looking at had its standard makers plate under the bonnet but it was stamped with the higher rates.
Then inside the cab its had a Land Rover Special Vehicles plate and it was stamped 4t under towing capacity. I never saw the log book unfortunately so cant comment but I imagine that just had its GTW and Trailer capacity at the higher rate which means a phonecall to I assume DVLA  Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197
Self confessed mileage hunter |
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9th Jul 2020 10:29am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16857
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I would imagine that either (a) the coupled brake installation would be type approved, and part of the approved installation involved replating the vehicle afterwards, or (b) some form of IVA was required afterwards.
I really don't think you could just fit a coupled brake kit and leave it at that. |
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9th Jul 2020 10:53am |
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