Fabricating air suspension to trailer
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  1. #1
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    Default Fabricating air suspension to trailer

    Hi,

    First of all sorry, not about machining this topic. Every now and then I need to transfer delicate goods and my current trailer has leaf springs so depending on load it could give quite harsh ride. So what I was planning is to convert it to use air suspension. I see there are affordable air bags so it wouldnít break a bank. I was planning to have very minimalistic design (read cheap). Bags, tank and valve. No fancy electronics or pump. So having fairly big tank with Schrader valve Iíd just fill it with as much as the compressor at home can produce (< 10bar / 145 psi) before the trip. When trailer is loaded, manually from valve adjust the pressure for correct drive height. That tank should be plenty for few adjustments and in emergency can fill it from gas station. Iím assuming if no leaks and load is static, pressure can maintain static as well. Am I right?

    Iíve tried to google how these systems work with little luck. My hesitation is on the air volume for suspension. So I was thinking that is the air volume inside the bags enough for super smooth ride? It gets progressive but does it get too progressive with small bags? So I was planning to have two tanks. One which is at max pressure and another which is at the same atmosphere as the bags. This way the progressivity would be reduced drastically as the air volume under load is considerable larger. However air line diameter restricts the airflow somewhat and that brings progressivity, but is it considerable amount? Or would this second tank idea just ruin it and have the suspension bottom out? Thoughts?

    Thanks for help.

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    These are dead simple but you are doing it wrong.

    Irv2 is an rv site and much about air ride can be learned there.

    You will need an air compressor, little one is all you need, like ones for filling tires.

    Many pick up truck upfitters have many fo install.

    Next is ride height valve, it is simple lever activated that attacks to frame and lever to axle.

    As load changes the height changes resulting in lever moving to either add or release air.

    Make sure good and correct shocks to reduce air assisted oscillation.

    Properly setup it is dead simple and no touching

    Sent from my SM-G781V using Tapatalk

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    Timbren or some one else makes an air ride trailer axle assembly (actually there is no axle, just a stub on each side)

    They would be the best to advise you on your question.

    FWIW, air ride semi trailers have height adjust (automatic) valves on the axle, someone here might chime in shortly to further
    the information.

    6.5x12 Air Ride Utility Trailer | Pirate 4x4

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    Air by itself will not provide a smooth ride on a light trailer, it's too compressible and when combined with the soft rubber bags, squishy and bouncy. IMO you'd do better to invest in high quality shocks. Ideally ones that you can tune the compression and rebound valving. Infact quality shocks will be even more critical in an air suspension than a leaf or coil spring system.

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    You may well be on the right track. I've certainly seen trucks advertised with air bag suspension for better ride.
    Attached is Firestone air bag design manual. This should help you with your design.
    Good Luck
    Bob
    https://www.firestoneip.com/content/...sign-Guide.pdf

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    We had a similar issue. Was picking up and delivering parts on a trailor and didn't like the rough ride. We instead got rid of the trailor and bought a flatbed truck for transporting.

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    Same issue...our solution was to remove leaves from the springs( yes this reduces the load capacity...duh) but, our application did not need the rated load. Obviously that trailer became specific for that use.

    Then we added pickup truck HD shocks , made some brackets and installed.

    Totally changed the way the trailer pulled....everything just smoothed right out.

    You also MUST balance the wheel assemblies.

    Way to many variables here to tell you how, what to do......it did work for us

    Trailer still in use ,has been now for 15 years

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    Default Fabricating air suspension to trailer

    Most of the problems with rough riding air bags is the ability to transfer air quickly. Look at a greyhound bus (high end rv) they have very large air lines or they are integral with the frame structure. I built a rv on a class 8 truck chassis, 45 ft tandam axle air ride conventional. I experienced harsh ride which made me look at bus suspensions, i added a air storage tank between the air ride height and air bags, helped slightly next step is to add 1.5 inch hose to the air tank, that should improve it. Time will tell. Fully loaded semi trucks ride pretty good but the weight is there. From racing experience shocks are for control, springs, air is for load- with air being more progressive


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    I have a friend that builds trailers he swears by the airstream suspension set up he buys them from wrecked airstreams and puts them in his trailers
    Don


    Sent from my iPhone using Tapatalk Pro

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    Ive worked on plenty of air bag busses and trucks ....and none had bigger than 3/8 black nylon air lines to airbags or valves.....As to ride ,an airbag is no different to a tyre with 100psi in it ...all give a rough ride when carrying 8.5 ton an axle......Airbags are also susceptible to blowouts ,so carry a spare at least......also need shutoff valves on each airbag in case of blowout,so you can stop air loss.

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    Must not been this kind of bus, this is a mc9 rear suspension or 8 your looking at the air beam which is rusted out , common problem the round flanges is where the bags bolt to. You can buy a plate with a fitting for the air line and bolt on for a repair but if you donít use the right bag it will ride like a dump truck. Experience is the best teacher they say! There is a different larger airbag that works , the air frame acts as a reserve for the better ride. Found by modifying the airbag with a 1 inch airline going to a large tank does the same thing.


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    I used to take busses for the yearly Govt inspection......Inspector would get in the bins under the floor and probe with a long screwdriver.....and get covered in showers of rust....Before the inspection ,I used check for cracks etc in the frames (all light gauge fabrication) and cover the cracks in grease like the unis had thrown it off.....One bus had a cracked axle housing under the spring seat.....the maxis used to blow crud there too,and the inspectors never spotted the cracked housing.....Busses have got 20 years,then mobile homes or scrap,so that takes care of faulty busses before anything drastic happens.

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    A little stainless in the right places and that wouldnt have been a problem, still would crack though I guess


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    Quote Originally Posted by john.k View Post
    I used to take busses for the yearly Govt inspection......Inspector would get in the bins under the floor and probe with a long screwdriver.....and get covered in showers of rust....Before the inspection ,I used check for cracks etc in the frames (all light gauge fabrication) and cover the cracks in grease like the unis had thrown it off.....One bus had a cracked axle housing under the spring seat.....the maxis used to blow crud there too,and the inspectors never spotted the cracked housing.....Busses have got 20 years,then mobile homes or scrap,so that takes care of faulty busses before anything drastic happens.
    I see all kinds of rust on vehicles around here ..... but Ozzland ?????

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    Nothin different here...steel rusts like everywhere else.....industrial fallout accelerates rust ...as does water .....most busses are washed out inside and out once a day,tour coaches anyway.

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    Quote Originally Posted by john.k View Post
    Nothin different here...steel rusts like everywhere else.....industrial fallout accelerates rust ...as does water .....most busses are washed out inside and out once a day,tour coaches anyway.
    There are used car dealers around here that specialize in bringing up cars from the "Rust free south" as they don't get any salt damage.

    I'm not doubting you, but I can't fathom how Ozzland vehicles would get much rust, just from rain, and frequent washings.

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    I got a callout once to a coach that was leaning over at about 30deg ......It was a school tour,and one of the little monsters had shut off all the airbags on one side of the coach overnight ....When the air pressure got up ,the other side bags filled ,and tipped the bus over at a crazy angle......Driver tried to keep going ,but the cops pulled him over .......All the dummy needed to do was turn on three valves in plain sight on tops of the airbag mounts....the bosses pretty quick got me to remove the handles from the valves,so a wrench had to be used on the squares to turn the valves .......anyway,even though every coach had spare airbags in the bin,none of the drivers would get their hands dirty changing one.

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    They do make progressive leaf springs that give a softer ride unloaded yet can accommodate heavy loads when necessary. A good spring shop could help you with that or possible re-purpose truck springs.

    One of the old hot rodder tricks was to grease between the leaves and then wrap them with electrical tape to retain the grease and keep them clean. Made the springs work more smoothly.

    I would be cautious of using air bags at max pressure unless they are commercial truck components. The ones sold to DIYers can blow out suddenly with nasty results. years ago I bought a used muscle car with bags inside the rear coils. On advice of the old timers I swapped them out fro progressive rate coils..

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    Quote Originally Posted by digger doug View Post
    There are used car dealers around here that specialize in bringing up cars from the "Rust free south" as they don't get any salt damage.

    I'm not doubting you, but I can't fathom how Ozzland vehicles would get much rust, just from rain, and frequent washings.
    Rust free is a relative term. Up here it's road salt in winter that causes premature rusting. The southern cars aren't as exposed to salt unless they are from coastal areas where salt spray from the ocean gets at them.

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    Quote Originally Posted by Scottl View Post
    Rust free is a relative term. Up here it's road salt in winter that causes premature rusting. The southern cars aren't as exposed to salt unless they are from coastal areas where salt spray from the ocean gets at them.
    Where did I go wrong in my post sir ?


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