Independent trailer suspension DIY question - Page 3





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  1. #41
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    Default Re: Independent trailer suspension DIY question

    That 70mm wheel base difference in the 70's era Renaults was purely for the purpose of fitting long transverse torsion bars to the rear suspensions to get long wheel travel and a soft ride, it had no influence on ride over corrugations, and minimal influence on handling. Near all French cars of the era aimed to have robust long travel suspensions as it was said their roads were the most uneven in Europe.
    Another good example of the same practise was in army tanks, some tanks from that era (Leopard II and III, M1 Abrams, even our own Loggim prototypes) also employed transverse full width torsion bars (on up to 7 axles), with the whole one side offset forward to the other side to allow the system to fit in. The fact that the double floors helped with mine resistance was a secondary bonus.
    Name:  tank torsion bars.JPG
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    [The other tanks of the era (Challenger 2, Leclerq) followed Citroen with hydropneumatic suspensions, an almost universal practise now with the Japanese, South Koreans and Russians following that]
    Last edited by Mike N; 2019/07/08 at 04:47 PM. Reason: replaced track with wheel base
    '89 LR 110 V8

  2. #42
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    Default Re: Independent trailer suspension DIY question

    The Tatra Kolos 813 also have a total offset of wheel position from left to right to accommodate the tube chassis/drivetrain setup so as to drive each side sideshaft off the opposite side of the crownwheel. Does not seem to cause handling problems either.

    I know that has nothing to do with this suspension discussion, just mentioning it as a point of interest that wheels can have a different position between left and right.
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  3. #43
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Michael11 View Post
    Hi everyone

    I would like to know if anyone has built a trailer or Atleast an independent suspension such as in the picture. I would like some direction with dimensions and what shocks and springs were used.
    Use RUBEX split axles.
    For SA Google "RUBBERIDE".
    Super easy to fit , unit construction.
    Fitted 2 sets each to 7 drill rod trailers in Congo.
    Used the 3.5 ton ones.
    Trailers carry 7 tons of rods.
    Never had a roll over in 3 years.
    Very harsh open cast mining conditions.

  4. #44
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by 4eTouareg View Post
    On the average family saloon or bakkie, the weight distribution is not even close to 50-50 front and back.
    Performance car designers go to great lengths to get it as close as possible.

    Adding load anywhere compromises the distribution even further.

    It is therefore a very 'general' statement to say that 4-wheel vehicles have equal weight on all 4.

    I agree that suspension design for trailers differs a lot from that of 4 wheel vehicles, though.
    Yes, you are correct. Front engined cars have as much as 65% of their weight on the front wheels, and only 35% on the rear wheels, - that's as the car leaves the factory. Rear drive cars split this about 55/45 front to rear. With boots mainly being in the rear, these values may be offset.

    So to correct myself, on an unloaded front wheel drive car of 2000kgs, the front wheels go from supporting 650 kgs to a whopping 1300kgs in a maximum cross axle situation in static conditions. At speed these loads are even more accelerated, but I excluded this point because this compound applies similarly to both trailers and vehicles. The important point to take away from this is that with increasing upward compression of the spring, there is increasing downward load being applied by the car. With a trailer, there is no increasing downward load, the load actually becomes lighter, and you're more likely to flip the trailer.

  5. #45
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    Default Re: Independent trailer suspension DIY question

    Heinz, as you are clearly an expert on the matter. How many trailers with independent suspension have you built and of those how many have actually rolled? What issues have you incountered with these builds?
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  6. #46
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Congo View Post
    Heinz, as you are clearly an expert on the matter. How many trailers with independent suspension have you built and of those how many have actually rolled? What issues have you incountered with these builds?
    Thank you for the cudo, but I suspect you're into your mischievous stuff again. Last time we had a ding dong, you left the ring with a bloody nose. But let me answer your question.

    I am no expert in suspension systems (and don't claim to be an expert in anything). I only have 11 years of schooling. I never did standard 7, but managed to obtain an average matric mark.) I'm on record numerous times for saying I am neither an engineer, nor a camper. (Just in case you've missed this before.) I don't have any other tertiary education either. What I do have is an inquiring mind, a good work ethic and an appreciation for honesty.

    I have only ever built one trailing arm suspension trailer (ex-Burquip parts) that was supplied to Stellenbosch University together with a leaf-spring suspension that I designed. These were evaluated by a student as part of his thesis on whether it would be possible to design a computer model that would predict the performance of suspension systems. He used the practical analysis of the two systems (which I built) and compared these against his model. Upon completion of the student's task, both Hilton Milward (Burquip's resident engineer) and I, set up a meeting with Professor Corne Coetzee on November 9th and 10h30 (I keep my diaries). Hilton and the good Prof had an engaging discussion, looked over graphs, and Hilton expressed his surprise at the negligible difference between the two systems - something like a few percentage points. I mention names and places in case you'd like to verify my claims.

    The issues I have with independent trailing arm suspensions is discussed in my numerous posts in this thread. Start at the top and read again.

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  8. #47
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Heinz Modricky View Post
    Thank you for the cudo, but I suspect you're into your mischievous stuff again.
    Soos my swaer sal sÍ..."Nou't jy sy dr*l t'rug gedruk"

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  10. #48
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    Default Re: Independent trailer suspension DIY question

    Thank you for the history lessen. So no actual production model? And the claim that they will roll over is based on this thesis as well?

    Why the insults? It was a honest question

    The reason for my question was that the studies and FEM test that I have seen from Alko Germany have shown a marked imprevent on minimising road vibration being transmitted to the trailer body where rubaxle or Independant trailing arm were compared to slipper type leaf springs. (I will not again become involved in this bun fight as I do not need the personal attacks from people that have nothing helpful to add to a discussion)

    To further this it has become the norm in countries other than SA to rather use the trailing arm suspension.
    I appreciate the fact that you were part of a study on this. I do how ever not fully agree on your statement that the coils are a major cause of trailer roll overs. There are many other factors involved and I do believe that not only coil sprung trailers have rolled over.

    I do believe that this is a free market and if the customer want's Independent suspension then the customer gets Independent suspension. (As long as it is save and reasonable to do so)
    Last edited by Congo; 2019/07/09 at 03:07 PM.
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  11. #49
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Bullterrier View Post
    Soos my swaer sal sÍ..."Nou't jy sy dr*l t'rug gedruk"
    Personal insults like this ended the previous discussion as well.....thank you for your well thought out and helpful responce to the question.
    Land Rover is not a vehicle it is a cult!
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  12. #50
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Congo View Post
    Thank you for the history lessen. So no actual production model? And the claim that they will roll over is based on this thesis as well?

    Why the insults? It was a honest question
    Really? Did you not read the thread?

    Why would I produce something that I cannot see benifit in for my clients?, or do something that I think may endanger their lives?

    So by your advice, when you test something, you see its potential failings and then still go into production with that concept? Or you see someone make a mistake, but you do it yourself again just to prove the point?

    I've explained the shortcomings of trailing arms as they are currently employed on trailers - numerous points. There is not one single response showing that trailing arms have practical benefit. (I'm not saying there isn't, but I've yet to be shown what this may be.)

    There is no insult.

  13. #51
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Heinz Modricky View Post
    Really? Did you not read the thread?

    Why would I produce something that I cannot see benifit in for my clients?, or do something that I think may endanger their lives?

    So by your advice, when you test something, you see its potential failings and then still go into production with that concept? Or you see someone make a mistake, but you do it yourself again just to prove the point?

    I've explained the shortcomings of trailing arms as they are currently employed on trailers - numerous points. There is not one single response showing that trailing arms have practical benefit. (I'm not saying there isn't, but I've yet to be shown what this may be.)

    There is no insult.
    Let's just say that our team likes a challenge and improving on the old to make it better.

    I look at the possible failure and see if and how we may improve and come with a better product that actually works well. We did that with the custom eye to eye leaf springs.
    It works.
    We did that with the Independent trailing arms.
    It works.
    And it works great for us and our clients. No roll-overs........yet, people do stupid things sometimes.

    I said before, The major cause for metal failures is vibration.
    You will still have to canvince me that metal on metal gives the same vibration damping as metal on rubber or that a leaf spring has the same vibration damping as a coil spring. It is basic engineering principles.

    On your side I know that a slipper spring is a hell of a lot cheaper and will do a similar job, but for me "similar" ain't good enough.

    Now looking at the OP question he wanted to know where he could find parts and dimensions to build or buy a trailing arm setup. I think we answered the question.
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  15. #52
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Congo View Post
    Let's just say that our team likes a challenge and improving on the old to make it better.

    I look at the possible failure and see if and how we may improve and come with a better product that actually works well. We did that with the custom eye to eye leaf springs.
    It works.
    We did that with the Independent trailing arms.
    It works.
    And it works great for us and our clients. No roll-overs........yet, people do stupid things sometimes.

    I said before, The major cause for metal failures is vibration.
    You will still have to canvince me that metal on metal gives the same vibration damping as metal on rubber or that a leaf spring has the same vibration damping as a coil spring. It is basic engineering principles.

    On your side I know that a slipper spring is a hell of a lot cheaper and will do a similar job, but for me "similar" ain't good enough.

    Now looking at the OP question he wanted to know where he could find parts and dimensions to build or buy a trailing arm setup. I think we answered the question.
    You raise an interesting point. Would you mind indicating the organisation you represent and who your team is. Not stirring, I just find Heinz's point of view reasonably convincing and would like some basis to evaluate yours, thanks.

  16. #53
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    Default Re: Independent trailer suspension DIY question

    I am not a commercial member here but there is a link on my profile to my SA website
    Land Rover is not a vehicle it is a cult!
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  17. #54
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    Default Re: Independent trailer suspension DIY question

    [QUOTE=Congo;4180555






    You will still have to canvince me that metal on metal gives the same vibration damping as metal on rubber or that a leaf spring has the same vibration damping as a coil spring. It is basic engineering principles.


    [/QUOTE]

    I'm not taking any sides here but a coil spring has no damping and will return the stored energy, therefore it needs a shock absorber to stop the wheel from bouncing. A leaf spring has internal damping due to the friction between the blades absorbing some of the stored energy, therefore you can run a leaf sprung trailer without shocks (or dampers) without wheels bouncing up and down.

    I think that is a basic engineering principle.

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  19. #55
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    Default Re: Independent trailer suspension DIY question

    Congo, I don't know what your beef is. There can be no question about the intent of your post to me "Heinz, as you are clearly an expert on the matter."

    You may recall slagging off 3CR12 in some posts I made about the use of 3CR12 in Metalian trailers. (Forgive me for not wasting more time in referring to these posts, but I can find them if you need reminding.) I wrote to you privately, providing you with technical material. I went to great lengths to show you the benefits. I did not ridicule you on public forum as you did to me and my brand at the time. At the time I did not know who you were.

    Then on 15 October 2016, you entered another discussion, very similar to this one, where you claimed to have a team of engineers working on suspensions, that you did computer simulations and the culmination of 4 years of research, to produce a double eye leafspring that had an 84% improvement on eye slipper types. You dissed off my trailer suspension as being cheap chinese rubbish only good for moving furniture. You had engineering "proof" of your claims, but did not want to provide them to me (or the forum) without an NDA. You sarcastically asked me if I even know what a military eye is ?? (Your description - I know this as a military wrap.)

    Soon forum members started working out possible motives for your subversion attempts and it began to backfire on you. So much so that you had Dirk remove the thread. I however kept a copy. I'll save you the embarrassment. Throw the towel in now, or take a knock out punch in the next round.

    I'm tired of your antics.
    Last edited by Heinz Modricky; 2019/07/09 at 04:37 PM.

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  21. #56
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Congo View Post
    I am not a commercial member here but there is a link on my profile to my SA website
    Nudge nudge, wink wink.

    Why don't you just pay your fees and become a commercial member.

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  23. #57
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by faniedup View Post
    I'm not taking any sides here but a coil spring has no damping and will return the stored energy, therefore it needs a shock absorber to stop the wheel from bouncing. A leaf spring has internal damping due to the friction between the blades absorbing some of the stored energy, therefore you can run a leaf sprung trailer without shocks (or dampers) without wheels bouncing up and down.

    I think that is a basic engineering principle.
    Have a look at page one of this discussion, you will see that the coils are fitted with a dual shock setup. The energy is absorbed by the shocks.

    On the leafs the energy created by the road vibration must go some where. Heat and friction yes but as it is metal on metal a substantial part is transferred to the vehicles chassis. Hence vibration, vibration creates metal fatigue, metal fatigue leads to component failure.

    And most important....... coils are cooler.
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  24. #58
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Congo View Post
    . .........I do how ever not fully agree on your statement that the coils are a major cause of trailer roll overs.......
    In terms of toppling over, do you believe that coils having a travel of say 200mm is any different to leaf springs with travel of say 50mm?

  25. #59
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    Default Re: Independent trailer suspension DIY question

    Quote Originally Posted by Heinz Modricky View Post
    Congo, I don't know what your beef is. There can be no question about the intent of your post to me "Heinz, as you are clearly an expert on the matter."

    You may recall slagging off 3CR12 in some posts I made about the use of 3CR12 in Metalian trailers. (Forgive me for not wasting more time in referring to these posts, but I can find them if you need reminding.) I wrote to you privately, providing you with technical material. I went to great lengths to show you the benefits. I did not ridicule you on public forum as you did to me and my brand at the time. At the time I did not know who you were.

    Then on 15 October 2016, you entered another discussion, very similar to this one, where you claimed to have a team of engineers working on suspensions, that you did computer simulations and the culmination of 4 years of research, to produce a double eye leafspring that had an 84% improvement on eye slipper types. You dissed off my trailer suspension as being cheap chinese rubbish only good for moving furniture. You had engineering "proof" of your claims, but did not want to provide them to me (or the forum) without an NDA. You sarcastically asked me if I even know what a military eye is ?? (Your description - I know this as a military wrap.)

    Soon forum members started working out possible motives for your subversion attempts and it began to backfire on you. So much so that you had Dirk remove the thread. I however kept a copy. I'll save you the embarrassment. Throw the towel in now, or take a knock out punch in the next round.

    I'm tired of your antics.
    And here we go again......no motive no intentions, never named my product, did not attempt to discredit your product, asked you a question about Independent suspension and as you beforehand in this tread claimed to have extensive experience I thought it would be appropriate to refer to you as an expert. Apologies for calling you an expert.
    You know that the reason for the other tread being locked was because uncalled for personal insults were being thrown around without it benefiting the discussion simply because of your support here. Was I wrong in my thinking, possibly, do I believe it to be an improvement on the old, most defenately.

    You are welcome to supply and build your product how you see fit. Allow me to do the same.

    Have a great day.
    Land Rover is not a vehicle it is a cult!
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  27. #60
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    Default Re: Independent trailer suspension DIY question

    For the benefit of readers that may be confused. Shock absorbers are there to slow the compression rate of the coils. This also has the effect of hardening the suspension. (Think of your car boot lid fitted with a gas strut. The quicker you try to open or close it, the more the resistance.) Two shocks are used in trailing arms because of the way they are mounted - at a 45 degree angle. They do this because they don't have the vertical height to mount them upright. This means that their effectiveness is roughly halved - hence having to fit 2 (per side). That's four shocks to replace because the design is compromised.

    One benefit of this is that they each only do half the work, and don't heat up as quickly. The big negative of course is that when they fail and you are far from getting a replacement, the entire suspension is severely compromised.

    If you look at the evolution of trailing arms, you'll note two things happening:

    1. Shocks are being mounted more vertically.

    2. The massive travel is being reduced. So much so, that some trailers that are too heavily loaded, or that are travelling on really bad roads, are destroying the bump stops - because these are now being employed to limit the travel.

    Coil springs generally have a reasonably constant compression load, so they need to be more accurately matched to the loads that they will experience. Because of this constant compression, they are relatively harder in the initial stages of compression and softer in the final stages of compression - which is the opposite of what you want. (Coil springs can be designed with differing coil pitch or from a tapered rod that will counter this effect.)

    A leaf spring is actually a diamond shaped flat blade spring (or a tapered blade) that is cut into strips and placed one on top of the other. It's easy to see that when you have a blade that is say 50 mm wide, it will hold "x" load with "y" deformation. Placing two blades next to each other will hold "2x" load with "y" deformation, or "x" load with half the deformation. So when the diamond shape blade is held at the sharp points and loaded the deformation in the centre is less than the deformation on the ends (because there is less steel to support the load on the outer ends). When this diamond shaped blade spring is "cut into strips" and placed one on top of the other, the outer ends of the spring is softer than the centre, giving you a progressively stronger spring as the deflection increases. Adding an overload blade with a gap between the spring pack and the overload blade, further increases the resilience of this design.

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