Trailer Suspension using front radius arms

[UNJUST]

I've had a bit of brain storm for a trailer suspension idea, Not ever content with what you can buy off the shelf and always wanting to be the black sheep in the paddock.

Been wanting to build myself a trailer for work for some time now (roughly 12x7f twin axle) but loath the leaf idea, yes i know its tried and tested but hense my comment above. also really hate a noisy trailer and sometimes the trailer will be near empty, sometimes loaded and hate the way a unloaded trailer rides. Trailer will be for my concreting business.

Thinking of using some Radius arms off the front of what ever, (patrol, 80, rangie) coil springs, shocks and pan hard rod. Now obviously running twin axle i probably wont have room for both sets of arms running in the same direction, for the front axle the arms would have to mount back wards and for the rear axle, the arms would be mounted as it would be in the front of a coiled truck. Pan hards would have to mount on the same side so that wheels stay on the same path. Could also run airbags or polyair inside the coils. Most likely be running 30/31s tyre/wheel.

There is plenty more to this that ive thought of but this is just the basic idea of it, does any one see any fatal problems with this? Good/bad idea? Anyone done somthing similar to this? Had thought of going independant but i think thats a bit extreme for a work trailer. not to mention alot more work.

Any input would be great..

JLowe

[ozy1]

i dont see it being a problem, except you will have to set the panhards up, id be thinkin as close to paralell with the ground as possible, but having a load on it will change them depending on what spring rate you go with,

but it could work well, if built right,

[jet-6]

Its totally do-able, just wont be the cheapest thing out

[265grunter]

this is a constant idea i have but it comes back to size of the completed unit and the weight compared to conventional leaf spring set up.also the clamping of the axle to the arms/rods may be an issue if it were involved in an accident.i have patrol suspension bits lying around so its probably going to happen using these bits but i need an engineer to stamp/certify the finished product.trying to keep a low deck height with the coils is an issue[tandem car trailer].....

[Shadow]

How are you going to handle the load sharing?

I doubt you will get it rated as a load sharing suspension without an engineers report on the design, which will cost alot?

[fester2au]

Ignoring the load sharing issue for the moment would it be easier to package with the radius arms running from the middle out. Obviously they won't be centred as trailer would not be long enough but you get the idea - back to front, front to back rather than back to front x 2.

[UNJUST]

Thanks for all the replys

How are you going to handle the load sharing?

I doubt you will get it rated as a load sharing suspension without an engineers report on the design, which will cost alot?

Can the load sharing thing be explained a bit more for me? isnt that where rocker or slipper style leafs come in to play?

this is a constant idea i have but it comes back to size of the completed unit and the weight compared to conventional leaf spring set up.also the clamping of the axle to the arms/rods may be an issue if it were involved in an accident.i have patrol suspension bits lying around so its probably going to happen using these bits but i need an engineer to stamp/certify the finished product.trying to keep a low deck height with the coils is an issue[tandem car trailer].....

Heavy duty leaf packs couldnt be that light could they? Would there be problem with welding mounts to the axles for the radius arms?

i dont see it being a problem, except you will have to set the panhards up, id be thinkin as close to paralell with the ground as possible, but having a load on it will change them depending on what spring rate you go with,

but it could work well, if built right,

Yes Panhard angle will be one issue, to get the best of both worlds, but im certainly not going for maximum articulation but i know exactly where your coming from. Yeah i feel like it could work well, but as you said "if built right"

Thanks again, keep the ideas coming

JLowe

[ozy1]

With load sharing suspension, if the front axle slimbs a gutter, the rocker setup then forces the rear axle down, to the ground, thats where your load sharing comes into play,

with a standard set up, like slipper springs, or your setup, with radius arms, you will not have the load share advantage, if one axle is on a gutter the other will just be relaxed with no weight on it,

with load sharing trailers can have a GVM from 2T to 4.5T, with the right breaks
non load sharing setups you get upto 2t and thats it,

what capacity are you aiming for?

[Slunnie]

Re the panhardsm they wont need to be parrallel to the ground, there is no steering and its just a trailer. You'll need to confirm tyre to guard clearance, but thats no different to a car.

Re the central pivot for the radius arms and axle seperation, you can run seperate radius arm chassis mounts which are offset and crossed over - in a similar way that the military perentie 6x6 Landrovers have crossed over their leaf spring packs to load share and bring the axle seperation in closer. Obviously this wont load share in your application

Re load share, trucks have been doing this for years with air suspension. I've never looked into how it is done, my assumption is linked air suspension. These springs may also be good for packaging and variable loads. I've never heard of a trailer requiring an engineers report.

[ozy1]

Slunnie, the only reason i mentioned having the panards parallel is with big loads its less likely to push the axles too far off centre, but i suppose it all depends on the stiffness of the springs used, go one better and fit a watts link

[Eddy]

Have built one ... is crap!



With coils or airbags, height becomes an issue. unless you build spring mounts into the suspension arms themselves.
Panhard rods on a dual axle will make the thing squirm on the road, pushing the towbar side to side over undulations.
So you are better with four link.
There is no problem with having both sets trailing; ie; front mounted, as there is no need for really long travel therefore no need for long arms.
Load sharing is a pain to get sorted, but can be done.

All in all IMO a complete waste of time. Far better to stick with the tried and true leaf spring set. A little attention to detail is all that is needed to make the thing tow more comfortably, and if you want it to be quiet, use nylon bushed springs and rubber mount the A frame.

At the joint I worked at, we built a bloke two 4.45 tonne capacity tri-axle trailers, on leaves, with rubber mounted A frames that travelled almost dead silent unloaded. (one for livestock & t'other a while later for machinery) They were magic on the rough station roads he travelled, and it was several years before he needed to have any cracks repaired.

[Gwagensteve]

Have a look at the suspension designed by Trak camper trailers for their camper trailers and T'vans. The guy that runs Trak is a rover nut and uses kinda what you are describing but runs a panhard per side, overlapping, so the result is independent suspension. with very little camber change, and a kind of self centering effect.

It is possible to apply this idea to a dual axle trailer, but it does appear load sharing is an issue, I've seen some of his prototypes dual axle trailers and from memory they were airbag so the bags did the sharing.

It's very elegant. He makes his own arms, but I think he started the idea with Rangie radius arms, coil design and shocks.

Steve.