Dean Lofthouse

Mis-information like this can really stitch a business up big time. It can take years to build something up for one comment to bring it all down. Peeps, think before you post.

As in the weight would be more over the rear axle ?

We will do this in a scientific way, fact only. Give me some time and I will service both my trailers. Adjust the brakes as per manufactures instructions and i will take both down to the mot station and put them on the test rollers and get an actual brake efficiency reading in forward and reverse. One of my trailers is a Meridian and Aire ratchet lever and the other a Bateson over centre lever. Two different systems. That way there is no speculation

I think its a legal requirement in parts of the USA

CJ... I don't get what you are saying. The 18% is a "minimum" requirement for reverse or forward. Are you saying that chocking is uneccesassary or that the brakes work equally well in reverse? Ive already held my hands up, apologised and said they do work well in reverse, but should still be chocked as per instructions Whats your point ?

Today I have spoke to two technicians from two different top brand trailer manufacturers. Both have said trailer brakes (for reverse parking) are only manufactured to meet current regulations of holding on an 18% slope. So in effect the forward braking efficiency far exceeds the reverse braking efficiency and if parking on a reverse slope, chocks should be used. If parking for lengthy periods of times on any slope forwards or backwards, chocks should be used anyway.

Break away cables were on trailers before auto reverse. They were intended for trailers coming unhitched whilst going forward.

No Humour needed Jaime, I hope its not taken the wrong way by anyone. The whole point of this is to point people in the right direction of chocking trailers when parking reverse downhill. It has been suggested that there is no need, but it is vital that trailers are chocked in reverse, whether the brakes work at 150% or 1% it makes no difference. If it comes to a court case you will be to blame 100% if you injure or kill someone because you didn't chock your trailer, there are no doubts there. I spoke to someone at a trailer place yesterday, he wasn't from technical though but did say, the brakes do work in reverse (which we know) but you must nudge the trailer backwards after the handbrake (ratchet type with energy store spring) has been applied, but it must be pulled up to the last notch with the energy store spring compressed fully. If you don't follow the procedure on the ratchet type brake the trailer will run off in reverse as if the handbrake wasn't applied. The over centre type hand brake must be applied to over centre ( which we know) and this type of system doesn't need to be nudged, it will put the brakes on if the auto reverse mechanism is triggered. What he couldn't tell me was if the brake force was equal to forward braking or reduced. He did say however that all trailers, whether caravans, chippers or standard trailers, must be chocked when parked in reverse on a slope and it would be negligent not to do so. All manufacturers require this. He also said that that previous to the introduction of the energy store trailer brakes had extremely poor reverse park braking if any. There has been new shoes/cradles introduced in that last year which are supposed to give near perfect hold but he would not comment on how perfect and emphasised the serviceability and adjustment make a huge difference. So CJ I hold my hands up and apologise for saying there is very little braking effort in reverse. But I don't apologise for recommending nobdy should park their trailer up without chocks

We have already established this apart from the last paragraph in bold My argument is that the full surface of the brake lining on the shoe does not contact the drum once the auto reverse mechanism has been activated, so the "full braking effectiveness" cannot be achieved. So the question is, what percentage of braking effectiveness is achieved ?

To simplify, the question that needs answering is: Do the brakes work as efficiently in reverse as they do going forwards with the handbrake applied?

I,m gobsmacked to say the least, something as importnt as that. Mines a pre historic license, so I,ve never taken a trailer test.

I do apologise....page 6 and 7

coupling and uncoupling procedure page 10 and 11 https://www.google.co.uk/url?sa=t&source=web&rct=j&ei=FIPiVKu4Jdb1asKkgOgG&url=http://www.knottuk.com/fileadmin/Knott-UK/usr/pics/Products/The_Complete_Package___Instructions/KF082_-_Trailer_Service_Maintenance___Repair_Handbook.pdf&ved=0CB0QFjAA&usg=AFQjCNEi_e5yslbvwaCAkc0QuaIhj9otzg

I, ll see if I can get time tomorrow to have a chat with a knott Avon ride tech dept and update the thread. See if we can clear it up properly

Just out of interest how many of you have serviced or even looked inside your chipper or trailer brake drums in the last 12 months or even ever adjusted them and i bet it isn't many. For these systems to work they need regular servicing which includes copper slipping r greasing the cam or slides on the auto reverse

Yes it does apply but not at full efficiency. It brakes with the leading leading edge which in forward rotation is the trailing edge. The forward rotation trailing edge is normally square and leading edge chamfered. This is what will give a bit of a "grab" feeling when the brake is applied when rolling backwards a little. But the braking force is nowhere near as effective as it would be in forward motion. The pdf list you have shown is a sliding shoe system which is more efficient than the older systems and if serviced and adjusted regularly is a very effective system but should never be trusted with a loaded trailer backwards down a hill. A chipper (and im not talking about a sub 750kg baby) should be classed as a permanently loaded trailer

The dual axles on your caravan will be more than capable of a braking force for a 3.5t trailer, so even at 50% capacity in reverse, they will have no problem holding the weight of your caravan. However, if they do hold, it may only take a slight nudge when hitching up to exceed their holding capacity (especially if in need of adjustment) and knock off the reverse cam, then your caravan may pee off on a holiday all of its own

Tim....the top chock will do fine, but back it up with the second then the third

Full braking force will never be achieved, once the auto reverse cam operates, the full surface of the shoes cannot contact the drum, only a small proportion. Yes the brakes will apply, but absolutely nowhere near 100%, I would say around 50% at a guess as the top section of the shoe has been drawn away from the drum, only the bottom section of the shoe where the cable enters contacts the shoe. Its extremely irresponsible to try and convince people the brakes work in reverse and you can park your trailer either way round without problem. I,ll say it again as a mechanical engineer with 35 years experience, specialising as a vehicle mechanic. If I,m proved wrong, I,ll hold my hand up no problem. I would never give false / ignorant advice trying to save face. This time in bold Trailers with auto reverse (including chippers) should, if possible be parked on a flat level surface. If the trailer has to be parked (unhitched) on an incline, it should be parked with its nose facing downhill. If it is not possible to park the trailer with its nose facing downhill, all wheels should be chocked, with suitable purpose made chocks.

Again....over centering is a term used for the hand brake lever itself to apply a strong force on the cable going to the drums. The force does apply a near fully loaded braking force to the shoes, but it still will be overcome in reverse if the incline and load combination is enough. If this wasn't the case, the auto reverse function would not work when fully loaded

I'll say it again for safety reasons seen as how I have been dismissed as wrong. Trailers with auto reverse (including chippers) should, if possible be parked on a flat level surface. If the trailer has to be parked (unhitched) on an incline, it should be parked with its nose facing downhill. If it is not possible to park the trailer with its nose facing downhill, all wheels should be chocked, with suitable purpose made chocks.

even on a brand new trailer

you are correct again in your assumption stevie

You are correct Stevie Auto reverse braked trailers should never ever be parked with the back facing downhill. Regardless of whether you use the handbrake or not the brakes "will" disengage if there is enough weight on the trailer to overcome the auto reverse cam. This is why everyone needs to take a trailer test, not knowing this sort of question kills