Legal A frame design

Discussion in 'Tech/Mech General' started by adammarshall, May 26, 2008.

  1. adammarshall

    adammarshall Deleted User

    I have read various posts on the legalities of towing A frames, where most seem to conclude that they are illegal to use (other than to recover a vehicle to a place of safety) because a car being towed on an A frame is regarded as a braked trailer and does not conform to the required legislation.

    I can’t understand why everyone seems to come to this view as I believe it would be relatively easy to design a truly legal A frame:

    Q1) Many posters on other threads have claimed that A frames are illegal because the towed cars brakes cannot operate at the required legal efficiency due to the towed cars vacuum pump not working because the engine is switched off.

    A1) Would it be legal to leave the engine running on the towed car to solve this problem? If this is not legal it would be easy to install a remote vacuum pump, powered from the tow vehicle that could be used to operate the brake servo. I believe this solution would meet all the braking requirements.

    Q2) Many people argue that the use of A frames are not legal because they don’t comply with the requirement to allow the trailer to be reversed by the towing vehicle without imposing a sustained drag and such devices used for this purpose must engage and disengage automatically

    A2) I don’t think the ability to incorporate an auto reverse feature into an A frame would be that hard. Why not just have a locking device on the coupling that is activated via the signal from the reverse lights? I am defiantly sure I could make something that would work. It really is not a hard task.

    I am also aware that it is difficult to reverse with an A frame, however why not just engage the steering lock on the towed car? I have read about the ability for auto reverse braking, but this is not braking and I can’t see any legal reason why you could not get out of the towing vehicle to engage the steering lock on the towed vehicle before reversing.

    Also I can’t see anything in the legislation that sets out the minimum requirements for reversing. There is nothing about reversing round corners, uphill, or for how long? This I am sure could only be interpreted by a court, and is not something somebody could categorically say is illegal or not.

    Q3) Other provisions from Regulation 15 and Regulation 86A of C&U require the fitting and use of a secondary coupling system in which the trailer is stopped automatically if the main coupling separates

    A3) Could this be achieved electronically? I know normally electronic braking methods are not allowed but is this different? Again if this could not be achieved electronically I don’t think it would be too hard to devise a mechanical solution.

    In summary I want to ask if I implement all my suggestions, is it legal to use a Towing A frame? I have read the various threads at length and believe if these things are implemented it would be fully legal.

    Adam
     
  2. superk

    superk Read Only Funster

    Joined:
    Aug 22, 2007
    Messages:
    503
    Likes Received:
    57
    Location:
    Devon
    Probably and Good Luck:BigGrin:
    We look forward to seeing you on Dragon's Den
    Keith
     
  3. ruffingitsmoothly

    ruffingitsmoothly Read Only Funster

    Joined:
    Jan 2, 2008
    Messages:
    1,395
    Likes Received:
    69
    Location:
    West of Southampton edge
    Whilst I can agree with most of the above I think that trying to reverse the car with the steering locked would undoubtedly cause some damage to the 'A' frame and/or the car's front end/steering!

    I have a 'brake buddy' which does seem to solve many of the braking problems, it is basically a compressed air piston attached to the brake pedal which pushes againt the front of the drivers seat to brake the towed vehicle and is powered from the cigarette lighter and operated by use of a small pendulum inside the unit, There is also a cut off lead attached to the vehicle that should it come adrift the brakes immediately come on.

    BrakeBuddy Vantage Select | BrakeBuddy - Braking systems for motorhomes towing a vehicle

    Regards Pat
     
  4. moandick

    moandick Read Only Funster

    Joined:
    Jul 28, 2007
    Messages:
    1,318
    Likes Received:
    112
    Location:
    Landrake, Cornwall
    Hi Adam

    Whilst I have no wish to detract from your post whatsoever, can I just say that there are at least half a dozen professional A Frame makers and fitters throughout this Country - do you not think that they will have tried and tested everything that you have suggested - and several times at that. :Eek!:

    Making and fitting A Frames is a thriving business - Chris Cox, for example has at least three months work in hand - but anybody who could/can make an A Frame that is totally, unashamedly legal would corner the market and make a real killing. :Eeek:

    The over-riding reason for being a grey area is both braking and reversing - now, I'm sorry but I do have to totally disagree with you about locking the steering to reverse. Just try steering a supermarket trolley (even in a straight line) when one of the wheels is locked in the wrong place. The A Frame 'base' plate fitting on the car is bolted/welded onto the chassis therefore you need some kind of swivel action to enable the wheels to align themselves in the direction of travel or you will simply 'skid' the front wheels over the road surface, cause un-necessary damage to the car/RV chassis or blow the tyres and tread. :Blush:

    I am currently trying to obtain an American A Frame, which I consider to much more substantial and suitable than a UK frame (for larger towed cars) and they have made tens of thousands of A Frames in the States (compared to hundreds in this country) - and even they haven't yet made a perfect A frame. :Sad:
     
  5. Camperian

    Camperian Read Only Funster

    Joined:
    Dec 1, 2007
    Messages:
    100
    Likes Received:
    0
    Location:
    Dorset - 6months, Spain - 6months
    While on the subject of A frames.

    I was returning to Portsmouth from Bilbao after wintering at Camping Marjal near Alicante. On the ferry I met a couple who recognised me (senior moment, have forgotten their names) who were stopped by the Policia and fined €150 for their A frame. The police would brook no argument saying the law changed in Spain in Jan this year. Strangely enough, I also met the Smithies who are members of MHFacts who were returning from Morrocco and were passed several times by police cars and motor bikes and not stopped once.

    It also appears that the Spanish Police take a dim view of singletons towing an A frame because of the reversing problem.

    As a singleton myself, I wondered about buying an inflateable dolly to fool the police, but decided against it because of the stares and comments I would get while stopped at traffic lights, filling up or just having a coffee.:Blush::RollEyes:

    Ian
     
  6. moandick

    moandick Read Only Funster

    Joined:
    Jul 28, 2007
    Messages:
    1,318
    Likes Received:
    112
    Location:
    Landrake, Cornwall
    Hi Ian

    I am sure you are 'Blowing up' out of all proportions - to the problem of being a singleton :Rofl1:

    ps. I saw the fill 'Airplane', too:Blush:
     
  7. superk

    superk Read Only Funster

    Joined:
    Aug 22, 2007
    Messages:
    503
    Likes Received:
    57
    Location:
    Devon
    That's interesting Ian I also heard secondhand about someone getting fined as they left the ferry in Bilbao towing a car on an A-frame - the reason given was that they didn't have marker boards on the car. (I always had LONG VEHICLE ans red/yellow cross-striped boards on mine)
    Maybe the local policia think they've found a money pot.:Smile:
    Keith
     
  8. adammarshall

    adammarshall Deleted User

    Ok I take your point about it is not a simple solution to apply the steering lock, as the wheels could lock in the wrong place. My answer to that would be to fit a secondary steering lock to the towed vehicle where you could align the cars wheels in the correct position and then lock. You could even use a helper to tell you when to lock. I don’t believe this contravenes the legislation as it just mentions auto reverse braking, and mentions nothing about alignment of steering prior to a manover etc. Another option would be to have some small brackets fitted to the underside of the car that a small custom made jack latches onto and lifts the front wheels off the ground when you want to reverse. You would only slide this under the car when you want to reverse. Again I don’t think there is a problem with this manual intervention, as it is not related to braking. The only thing that must happen automatically is the disengagement of brakes.

    With regards to your point about causing un-necessary damage to the car/RV chassis, this I believe is irrelevant to the legality. What is advisable is one thing, but what is legal is another thing. If you are able to “reverse under control” it is your problem that it causes unnecessary tyre wear, but does not make it illegal. Do you get my point? In reality everyone knows that the user would just unhitch their car for most reverse maneuvers and then hitch it back up again. I also mention the point that the concept of reverse under control has not been defined by a court. Does it mean reverse round an obstacle of cones for 1 mile? This is a grey area that can only be interpreted by the courts.


    You also say the following:

    Whilst I have no wish to detract from your post whatsoever, can I just say that there are at least half a dozen professional A Frame makers and fitters throughout this Country - do you not think that they will have tried and tested everything that you have suggested - and several times at that

    I take your point but don’t believe this is a barrier. I have developed things in the past that other people in their own market have failed to develop. I don’t think in this case it is any different.

    I would appreciate your comments on my solutions, and if implemented do you think it would be a legal A frame?

    Thanks Adam
     
  9. superk

    superk Read Only Funster

    Joined:
    Aug 22, 2007
    Messages:
    503
    Likes Received:
    57
    Location:
    Devon
    Making an A-frame that complies with the regs does not mean it will sell if it is impracticable or, even damaging, to use. My observations from practical use are that if the car's wheels are locked in the straight position then the only way you can reverse without scrubbing the tyres is straight back. However, because of the size of the 'pushing' vehicle i.e. the RV and its length compared to the towed vehicle this is not easy to do and the slightest movement off line will put a large force on the pushing point and the car will skew. :Sad:
    Keith
     
  10. RockieRV

    RockieRV Deleted User

    Another interesting thread on A frames!:Smile:

    Adammarshall are you a trader by any chance? Or does your experience come from using one? I am just curious.:Smile:
     
  11. adammarshall

    adammarshall Deleted User

    You said that:

    “Making an A-frame that complies with the regs does not mean it will sell if it is impracticable or, even damaging, to use”

    I am aware of this however my only concern is developing an A frame that is on paper legal. I don’t care if it is impractical or causes unnecessary wear. I don’t believe this is an issue, as in reality you and me know that when people use A frames 99.9% of the time they unhitch the car to reverse.

    The only real difference to the user would be on paper they have something that complies legally, and avoids fines / prosecution. Just because you can inconveniently set the A frame up to comply legally on reverse maneuvers, does not mean that the user will have to do this. It mealy shows to the powers that be that it can be done. As long as it CAN be done, the user is free to use whatever reversing method they want e.g unhitching the car.

    Thanks Adam
     
  12. peterfuller

    peterfuller Deleted User

    Just out of interests does anyone know what effect jacking up the back of a car (so the back wheels are off the ground) with a heavy duty jockey wheel would have on the ability to reverse the vehicle?

    If this would work you could have this jockey wheel mounted to the tow bar of the vehicle being towed and when you want to reverse it would work via the reverse lights activating hydraulics / compressed air and raise the entire back wheels off the ground. Then when you want to go forward this would lower the back wheels to the ground again.

    Does anyone know if this would work, and meet the reversing under control guidelines needed for an A frame?

    Peter
     
Loading...

Share This Page