Independent Suspension for tandem 3000 kilo tipping trailer?

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Shann Low
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Independent Suspension for tandem 3000 kilo tipping trailer?

Unread post by Shann Low » April 2nd, 2015, 1:42 am

Looking for any advice, tips, suggestions of supplier, of independent suspension etc for offroad 3000 kilo tandem tipping trailer.

I am planning to build a off-road dual use tandem trailer to be used for fire wooding (hence the hydraulic tipping) & on weekends etc to remove the folding sides and slide a camper unit onto it.

One issue I am struggling with is height/ground clearance.

It will be towed by a bitsamissing Triton 2.5 T/diesel dual cab 4 x 4 ute,

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so ground clearance only needs to be whatever the ute will clear.

If I go independent suspension with air bag / shock - it can be aired up for more under body clearance when carrying the camper and aired down when fire wooding for easier loading of wood and aired up again for towing it home to tip it off!.

So I am wondering whats the best off road independent suspension to buy to use as the basis for this trailer build (and who do I get them from?

Without axles / suspension being decided and committed too - I can't really start drawing the chassis plans etc to comply with ADR's etc.

All I've ever done before is build trailers with leaf springs and solid 45mm square axles from Martins trailer parts, so this is all a bit new to me - I figured maybe someone with experience might be able to point me in the right direction please?.

Saw this online underneath a caravan...

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No idea who makes / sells them or if they are any good for my proposed project?

Also saw these on ebay in a link on a thread in this section of the forum.

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http://www.ebay.com.au/itm/OFF-ROAD-CAM ... 27b9ea7646

Thanks in advance if anyone has any ideas / tips / suggestions / links / suppliers - or indeed reasons NOT to do it that way and just stick with standard square axles on leaf springs?.

typhoeus
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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by typhoeus » April 2nd, 2015, 7:36 pm

HI Shan low . Is the tipping mechanism going to be set up so the draw bar hinges where it attaches to the trailer, or will it have a full length chassis or other? if you are going to have the drawbar hinged at the mounting point, then you are going to load up the rear axle/ rear pair of wheels with all the weight when you are tipping. this could put undue strain on the shock mounts springs etc but require less power / effort to lift, as some of the weight will be behind the axle, and assist the tipping action . A full length chassis will require extra power to lift as you are lifting nearly all the weight, but all that weight is evenly distributed over all the wheels, so the rear set wont be overloaded. The compromise is to hinge the tray just behind the rear axle on a short chassis so the weight is evenly distributed over the wheels but some of the weight will be rearwards of the hinge and will assist with tipping,

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by mydmax » April 2nd, 2015, 9:45 pm

That design of swing arm with the coil forward of the axle uses shorter length coils to create the same degree of arc of suspension travel. Unfortunately having the coil where it is means there is a larger than desirable distance between the hub/bearing area and the swing arm pivots.
It also requires a heavier wire in the coil to hold the same weight as a coil behind the axle design would require.

Also, the axle leverage of the weight which is trying to bend/twist the arm is more than necessary, because the bearing positions are out further away from support because of the coil being in that position between the arm and the wheel. Maybe OK, but not ideal IMO.
Ideally the outer section of the arm should be about where the blue caps are sitting in order to get better support for resistance to twist forces and also to make the distance between the pivots bigger and more able to withstand wheel forces.

The axle which is welded to the rear RHS doesn't go full distance and stops at the outermost side of the arm.
Therefore the weld is essential and so is the integrity of the RHS supporting it, EG the axle doesn't form part of the whole length for equal stress delivery to the ARM.

The shocker clevis is where resistance of the shock will cause higher stress immediately after the axle end. Not good there, me thinks.

Just a few comments, to be aware of as well as the tipping/chassis items typhoeus mentioned above.

Shann Low
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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Shann Low » April 3rd, 2015, 5:06 am

I was aiming for full length chassis, not pivot at draw bar, & also no overhang at rear to counterweight the lift and assist with the tipping. Happy to put on a 4 or 5 stage 3 tonne hydraulic lift ram (or larger capacity) if that's whats needed.
Excellent points made about the two options depicted.
Can't thank you enough guys, REALLY appreciated!.

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Something along these lines...is what I had in mind but just swapping out the square full length axles and substituting independent coil / shocks / air bags, to get adjustable height by airing up or down.

The "issue" that's 'worrying me' with a dual use trailer like this, with square full length axles - is that it's not that suited to off -road use, particularly here in WA with our sandy tracks anywhere along the coast etc where you get wheel ruts and a center hump, such full length axles can tend to "drag" along the hump in the middle and if your not careful bend the axle.

I was thinking that independent suspension would give good / better ground clearance in the middle, if the axles were just stubs at each side?.

Also the ability to air the trailer up for that type of work creates even more clearance if needed.

The downside of a tall off-road trailer, is when you go fire wooding of a weekend and have to lift either every piece of chopped jarrah, or if your in a hurry, whole large diameter Jarrah tree rings, UP into such a high trailer floor!.

Again the ability to let air out of the suspension bags, and lower the trailer floor as near as possible to the ground can save a lot of work lifting the wood up into the trailer. Once its loaded - then air up the suspension bags with the on board compressor, and then tow it home and tip it off.

So the two uses (Fire wooding & camping trailer) - sort have different height requirements, for clearance off the ground. You don't want to fall 4.5 feet to the ground, out of your camper trailer at night in the dark, but you do want ground clearance to get the darn thing into some off-road camp situations!

Again you don't want it too high off the ground to fill with wood of a weekend but you do want good ground clearance to get into & out again with 2 tonne of wood on, from the best fire wooding areas in the forest!

So that's when a easy / cheaper "standard tandem full length axles setup" started to look like maybe NOT the best answer!.
That's a PIA, coz I just happened to have a couple new full length offroad axles rated at 1.5T ea handy...

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However;-
These are basically 3 inch tube axles with US Jeep stud pattern hubs.... and while 'rated' to carry 1500 kilos - they haven't got any fish plates attached to fix brake calipers to, and thus far I haven't been able to figure/find a way to fit disc brake rotor hubs to them, to turn them into braked axles - so they could be re purposed to work for the tandem trailer I wish to build!.

So I am "thinking" to myself maybe just flog them cheap to guys with single axle 750 kilo campers who have a Jeep wrangler tow vehicle, and want the ability to use jeep rims on their trailer, to match their tow vehicle, so they can carry just 2 spares and use the same wheels on their trailer and vehicle.

Then put the $ from flogging the jeep axles, toward buying a tandem independent suspension air bag setup, that's more suited to my dual use requirement! Maybe even get hubs with the same stud pattern as the Triton - so the same thing can apply - inter-changeable spare wheels with the trailer and tow vehicle!.

At least that's what I an thinking at the moment.

Going to get a guy designs trailers to design me a custom trailer plan that meets ADR's etc - but before he can do so, I have to decide on overall track width to match tow vehicle..., suspension design type and supplier - so the chassis width & layout can be designed to meet all the right specs from the get go!

So that's what has led me to asking questions.

I've only built trailers in the past with square full length axles (45mm square) from Martins Trailer parts here in W.A.

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VMS trailers like this one...

So I am keen to tackle a 3 tonne tandem tipper... to carry a pop top type camper when not being used as a firewood trailer.

But all this off road and independent suspension set up is a whole new learning curve for me.

I need to get my ducks in a row with the suspension to be able to get the trailer plans drawn... so I really need to know who to get the right gear thru and what gear to get!

If the best gear costs a little more, I don't mind paying to get the right stuff - so that it can be used for long trips away up to the Kimberly's maybe once in a blue moon.

Anyone who knows who i should go see or speak with about the right gear - please post up a link etc

I don't want to re invent the wheel if you off-road guys have worked all this stuff out ages ago... just asking to be pointed in the right direction is all.

Martins Trailer parts who I have dealt with for years, have a independent suspension option available but there's scant details about it on their online web site & PDF catalog that I can see, so was wondering if anyone's used them and whether they are any good maybe?

It's a big learning curve, sorry for the 101 questions.

Thanks heaps again for the input thus far, very much appreciated, I assure you.

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by typhoeus » April 3rd, 2015, 5:42 pm

well, seems like your doing your research. you have to weigh up how often will you need that centre clearance, and is it worth the extra level of complexity, additional weight, additional costs etc. with standard leaves, extra carrying capacity is as simple as adding leaves ( cheap ) full independent airbag would be fairly expensive initial outlay. By the way, what will you be using to tow it? 3 tons plus of trailer in the bush will need some grunt to keep moving !!

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Shann Low » April 3rd, 2015, 11:33 pm

Tow Vehicle!
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When it gets stuck the 7.3l F 250 should get them going again!. :lol:
Yeah that's the whole thing - doing the research!
The easy way would just be 2 x full length axles & leaf springs!.
But I see these off-road campers in all the 4 x 4 mags with independent suspension, and i keep thinking... yup yup yup - should do that! ;)
I typed "independent tandem trailer suspension", into google images... and zillions of different images came up... so now I am more confused than ever!

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It's scary how many different setups are out there. Getting one that meets ADR's is also a consideration - a lot of the depicted US products on google images may not meet our adr's for e.g.

Buying local would seem to be the logical answer?

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That one even uses a leaf spring!

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Shann Low » April 7th, 2015, 9:34 am

Well seeing Easters over- Cruisemaster Suspension in Qld were good enough to get back to me with all the details I requested about their suspension!
That's photos, brochures, specifications, etc for the trailer plans guy, & even how to fit them etc!
Can't complain about their customer focus - first rate!.
They are a complex system with a lot of components including things like a on board compressor and receiver tank hoses etc.
With a set of 12 inch disc brake rotors, hubs that suit the Mitsubishi Triton. dual shocks etc..
$8000+ for the suspension!
$3000+ for the hubs & brake calipers!.
Yikes! :crazy:
I guess if you have a $100K caravan - you might spend that on a suspension - but for a offroad camper / firewood trailer? :confused:
I am not saying "no" - it may end up this is exactly what we go for.... just suffering a little "sticker shock"... I wasn't planning to spend that on building the whole trailer!.
There's no question they are a great suspensions design & setup and I am sure it cost the company a bomb to get them certified / tested as ADR complaint etc.
I will make the effort today to get over to Martins trailer parts & see what they have in the way of details / price on their independent suspension.
Bit of an 'eye opener' - when you get right into the nitty gritty of this stuff!. :o

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Peter Aawen » April 7th, 2015, 11:54 am

If you still want to go down the Airbag route, check out the firestone airbags offered by people like the Airbag Man http://www.airbagman.com.au - they are the same bags that are used on heavy vehicles and many of the recreational vehicles, muscle cars, show cars etc and can often be fairly cheaply supplied to replace most coil springs in existing set-ups; the Airbag Man mob is well worth having a chat to. They provided a lot of help to me when I was setting up a full air suspension for one of our Patrols which worked very well altho due to the way I use it there are a few minor niggles that I'm working on sorting - great for an off road vehicle suspension tho!!

Buuut, taking this outside your 'initial thoughts' box just a little, how about looking further into alternatives. Briefly summarising what you've told us so far, I take that: you aren't uncomfortable with building the trailer itself; you want the trailer to have 4 wheels not just 2; you want to be able to raise/lower the trailer for the reasons identified in your earlier posts; you would like to avoid a beam type axle; and you don't want the set-up to be super expensive - does that cover the major points?? So, the way you see it so far, your options are to buy something like the stuff you've found above & set it all up under the trailer, but that gear is costly; or you could bite the bullet & revert to beam axles... Not much else seems to fit the bill so far, right?? That might be the case if all you are considering basically covers the types of trailer axle/suspension arrangements you are familiar with/outlined above, but there are more!!

Check out the suspension under Track Trailers - independent, load carrying, not a beam axle, and already proven in the Military & recreational on/off road fields; here's some reading http://tracktrailer.com.au/company-hist ... uspension/ This set-up works fantastically well on and off road, and if you look at using airbags in there instead of the coils, may well satisfy your needs/wants, but if you hafta buy it from Track Trailers it probably won't be cheap... still, worth an ask & looking at.

Then there's the 'other' Independent suspension types available out there that you might be able to adapt. What about sourcing a couple of IFS front ends from a wrecker, say a system with an upper torsion bar & twin wishbones each side carrying a spindle that holds the brakes & stub axle for the road wheel?! They are already ADR compliant, and you only need to adapting how you fit the to the trailer chassis. You could face the torsion bars from each pair of wheels away from the other pair, having one set running forwards and the other running backwards so they don't hafta interfere with each other. Fitting longer wishbones can give you more suspension travel than the limited travel these things usually have, but that will make for issues with the total usable trailer load bed width vs the wheel track; and there's even the possibility of replacing the hard chassis point on the end of the torsion bars with an airbag mounted point to give you the raise/lower feature you want. This all has been done before, my effort worked quite well for what it was & what it was designed for, altho it wasn't ever envisaged to support a tipping trailer or such a large range of travel - still, that's just details for you to work out suitably.

Then there's all those different suspension types out there that may work, they are most commonly seen on IFS vehicles but increasingly on the rear of independent susp vehicles; a workable trailer suspension could be adapted to your needs utilising things like McPherson Struts or maybe even coil overs & a twin wishbone/spindle arrangement - heck, I've made an Independently Sprung trailer using an HG Holden front end, altho that might be difficult to adapt to airbags or anything else to achieve the raise/lower feature; then there's stuff like the ALKO IRS that many caravans & other specialist trailer types run - again, that might not be easy to do the raise lower stuff, & you'd hafta look at the load capacity but check it out http://www.alko.com.au/vehicle-technolo ... nsion-irs/ I've been running that suspension successfully for many years on our 'off road capable' boat trailer... :)

So don't limit yourself to ONLY the stuff available from places like Martins or any other mainstream 'trailer' suspension, take a walk around a wrecking yard & check out the range of suspension types that are out there, put a bit of thought into how you could adapt any of them (the Airbag Man might help a lot there) to your needs/wants - maybe you could even consider making a trailer that has Independent Suspension that doesn't raise/lower.... have you thought about just raising/lowering the tilting load bed inside a fixed height chassis/frame with the suspension hanging off that?? :frog:

There's more than one way to skin this cat, just so long as you don't get stuck into the box trailer mentality! ;)
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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Shann Low » April 7th, 2015, 3:23 pm

Thanks so much Peter,

That's just the sort of input I am seeking!.

To answer your questions:-
Briefly summarising what you've told us so far, I take that:

1. You aren't uncomfortable with building the trailer itself; = No I am more than happy to build the trailer myself - its what I do - build VMS trailers, just not a 3 tonne tandem off-road tipper with independent suspension (yet).

2. you want the trailer to have 4 wheels not just 2; = Yes indeed, to carry a 2 tonne pay load on a 1 tonne trailer is ~3tonne ATM (GVM), which is all the Triton is legal to tow, and this requires 2 braked axles of 1500 kilo each according to:-
http://www.trailerparts.net.au/pamphlets/VSB1_V5.pdf

3. You want to be able to raise/lower the trailer for the reasons identified in your earlier posts; = In an ideal world - yes!
I was even thinking, maybe just use just 4 pairs of these monroe air height adjustable shocks, http://www.monroe.com/en-US/products/Max-Air with coils rather than actual air bag suspension?
I had a pair similar to these in a Ford Fairlane with on-board air ~30 years ago, and they worked a treat!

4. You would like to avoid a beam type axle; = If possible, yes. A "cranked" beam axle however might be another possible workaround maybe to get the ground clearance in the middle?

5. You don't want the set-up to be super expensive - does that cover the major points?? = Indeed - cost isn't the over riding factor, I figure If I am building it myself then I am saving some labor costs allowing me to spend a bit more on materials, but without going overboard.
I can see $12K suspension under a say $100K offroad luxury off-road caravan making sense.

Under a firewood trailer seems like 'overkill'

I am hoping to get plans drawn is all - so I have something to work too, knowing they will be ADR complaint, and so I can provide everything required to get my vin number, and the brake contribution form to get DOT licensing approval etc.

I could just wing it and build it myself based on what I've built in the past with these VMS trailers, but I am thinking it might be smarter to get plans professionally drawn to work to from Dion at :- http://www.trailerplans.com.au

For Dion to alter this basic 3 tonne tipper design;-

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- to my specific requirements I have to be able to supply him the engineering drawings that I intend to use for my suspension.

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Cruisemaster have done just that - supply me the above specs drawings etc which is great - just that the price is a bit of a concern unless I can't find another more cost effective solution in which case it might have to be that this is what I end up with!.

"Other options" is exactly what I'm now exploring & you have made some beaut suggestions for me to follow up. .

The trailer plans is handy to build too - and also allows me to work out my materials quantity & cutting lists - as well as having a design plan to show DOT inspectors at licensing to show compliance with the ADR's. We see each other every few weeks as I complete these 6 VMS trailers and drag them up to the inspection pits to get them licensed so we do this tango dance quite a few times now already. e.g. I put one trailer over a weigh bridge and took the print out to the licensing center to show GVM that matches whats engraved on the compliance plate etc and they wouldn't accept the public weighbridge docket coz the 'gorilla' operating it (with limited command of the english language) didn't have time to write the VIN number on the docket coz I was holding up about 5 b double rubbish trucks waiting behind me at the waste transfer station, so when I got to the licensing pits I had to then go to another weighbridge operated by his mate down the toad with the local tow bar business and pay to have the trailer weighed again and with the Vin number written on the docket & no I couldn't write the vin number on my weighbridge docket etc.

In essence my experience with these licensing peons thus far, has taught me to have all the paper work handy... and I's dotted and Ts crossed.... so an engineers design plans certified to DOT ADR's etc is sometimes worth the couple hundred $ it costs to be able to whip out a copy and slap it on their desk when they inevitably ask.

It's getting tougher and tougher to just build yaself a trailer these days compared to what it once was as I have been finding out in recent months with these darn VMS trailers.

So I am trying to get my ducks in a row before I start is all, - plan it all out - buy the components & build it to plan etc.

This one I'll build at home in my workshop rather than the trailer factory, because I can do this one at my leisure and take a little more time and care etc while the VMS ones are on a schedule for customers and time & cost is an issue, where I don't have the luxury of just putting it aside and talking time to think things thru - fab things to a higher / exacting standard that I will be happy to live with long term.

I have a 3 phase CIG transmig 310 with traveler wire feed on 8 meter lead, and my home workshop is concrete floor lights power etc, so i can leave it sit and work on it of weekends/ nights, when I feel like doing it, take the time to take photos and write a build thread etc.

I just don't get that sort of quality time available to me at the factory during the day...

I will probably build the slide in camper unit myself also again at my leisure and just send out the canvas work.

It could be a lengthy build process when finished.

But I am keen to make a start and need that plan to start buying materials...and stitching it all together.

The suspension can actually be purchased and attached / welded on when I am ready to flip it over.
All I need to get started is the plan and some suitable steel basically - which requires me to do my research and provide the plans guy 'Dion' with the specs of what suspension i will be using.

Least that's how I am thinking at the moment.

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Peter Aawen » April 7th, 2015, 4:01 pm

Unless they've changed massively, those air shocks aren't really meant to carry or lift loads above the vehicle's pre-set static ride height - they are ride levellers, not load lifter/carriers; and over the years I've seen soooo many vehicles with busted chassis components due to inappropriate use of them (&/or the 'coil insert' type ride levelling air bags too - not the black bellows firestone jobbies) and even more with busted shocks that have been asked to lift vehicles; so I wouldn't recommend them for raising/lowering a 3000kg trailer, even if just for loading & unloading purposes.

Hope it all comes together for you! :thumb:
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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by Shann Low » April 7th, 2015, 6:20 pm

Good to know - thanks again.
I am sure it will all come together eventually!
I tend to do a lot of research and approach these things "slowly, slowly, catchee - monkey" style - but I usually get there in the end!.
I've been trawling thru those links...you provided, very useful indeed.
It's amazing what's out there when you start to look, - the military style suspension is very interesting!
I have 2 projects on the go for the triton - a rear canopy and roof rack first then the trailer... so canopy will keep me busy while I research the trailer, and get the plans and materials into stock etc - then start in on the trailer!.
My lad (who all this is for) is capable of much of this... but he drives road trains 16 hours a day 12 days a fortnight and seldom has spare time to scratch himself, so I TRY my best to get stuff ticking along for him as best I can or it would just never happen otherwise!.

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Re: Independent Suspension for tandem 3000 kilo tipping trai

Unread post by CASH476 » April 11th, 2015, 3:51 pm

Trailer Parts do an independent Air suspension that may be worth looking at. You may want to consider the overall travel of the air suspension, is 100 or so mm going to make any real difference to your loading height considering the cost?

Also, unless you intend putting small wheels on your trailer, your tow vehicle is going to be lower in the centre than a solid axle trailer. Just some more things to consider :)

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