air bags

[heavyhaulerss]

is there a good way to keep my trailer air bags from stretching when unloading? I haul heavy single steel coils & I just noticed that I have 3 air bags leaking right at the bottom seam. I noticed this cause of all the rain water bubbling. the 3 that were leaking all all new.( installed within the last 6 months -3 years. the one original bag has no leaks yet. before buying all new bags. AGAIN... what can I do to keep the new ones from stretching until they rip also?

[chris1]

Chains between the frame and axle. You can also hook them shorter to use as a "lift" axle when MT.

[trucktool]

is there a good way to keep my trailer air bags from stretching when unloading? I haul heavy single steel coils & I just noticed that I have 3 air bags leaking right at the bottom seam. I noticed this cause of all the rain water bubbling. the 3 that were leaking all all new.( installed within the last 6 months -3 years. the one original bag has no leaks yet. before buying all new bags. AGAIN... what can I do to keep the new ones from stretching until they rip also?


Dump your suspension before unloading.

Proper shock absorbers should NOT allow the bags to over-extend.

[Kranky]

Are the new bags the proper ones for that application?

It seems strange that the ancient "original" bag is still OK, but the 3 replacements are leaking.

I agree that you should dump the air suspension before unloading.

[heavyhaulerss]

yes the bags are the correct replacement. I took the old one off & truckpro ran the numbers & gave me the original hendrickson bag. I relate the one not leaking to the same ole. (they dont make em like they used to). I have seen recently a lot of flat bedders with chains that appeared to be hooked in such a way. i dump my suspension valve. it is hooked up to my front axle. it does no good for the back. it would take too long to dump most of the air. I know I have wore out shocks. I guess i could chain the alxle to the frame, since it wont cost me anything & get new shocks on trailer & see if that is the problem. the chains I have seen recently are on newer trailer though & I would not think the shocks would be wore on newer equip. I also have noticed lately that my bags strech so much , that I wonder what has kept them in tact this long. maybe my shocks have worn completely out & that explains more stretching now than in the past. on chaining...I dont want to weld anything. would looping a chain around the axle to directly above around frame & leave limited slack work ?

[Bandit102]

My Wilson flat has nylon straps around the shocks to prevent over extension.

[Kranky]

yes the bags are the correct replacement. I took the old one off & truckpro ran the numbers & gave me the original hendrickson bag. I relate the one not leaking to the same ole. (they dont make em like they used to). I have seen recently a lot of flat bedders with chains that appeared to be hooked in such a way. i dump my suspension valve. it is hooked up to my front axle. it does no good for the back. it would take too long to dump most of the air. I know I have wore out shocks. I guess i could chain the alxle to the frame, since it wont cost me anything & get new shocks on trailer & see if that is the problem. the chains I have seen recently are on newer trailer though & I would not think the shocks would be wore on newer equip. I also have noticed lately that my bags strech so much , that I wonder what has kept them in tact this long. maybe my shocks have worn completely out & that explains more stretching now than in the past. on chaining...I dont want to weld anything. would looping a chain around the axle to directly above around frame & leave limited slack work ?

Check your ride height adjustment, sounds like it may be set too high.

[chris1]

The shocks should "top out" before the airbags over-extend. If they don't they are the wrong shocks. Chains/straps prevent the shock from breaking when the axle suddenly drops down.

[heavyhaulerss]

I set the height myself shen I replaced the leveling valve a while back. comapared to all others I have noticed, mine are not too high. mine are lower than most all I see. I have just put 1 chain on each axle to the frame, with just enough slack to the maximun height I want allowed. will be gettting new shocks & put them on this week. the shocks are original equip. thanks for all the advice.

[heavyhaulerss]

so far the chains I installed are working very well containing the air bags to an acceptable level. thanks 4 all the advice

[GMAN]

I was just wondering if you were able to get your shocks changed out and if that solved your problem, heavyhaulerss?

[heavyhaulerss]

No I have not had a chance to get the shocks on. it has rained for almost 2 weeks straight. & now that this week has been dry, I have more loads than I can handle. I am going to try & get it in my shop this wknd. I put 1 chain around each axle to the frame above it, with enough slack for the air ride, but will prevent the bags from stretching over their limit. the chains seem to work well so far. as easy as the shocks appear to replace, if I do it during the week I would have to give up a load & I dont want to lose any $$. been doing a lot of 120-150 mile runs & the time it would take me to install shocks, I would have to give up a load. if freight stays like it has for me this mon & tues, I'll just have to run 18 loads a week for 1 year to make up for what I have not earned in the past 14 months. last week I had 3 loads all week. so far this week I have 5 loads done & its only tues night. sooo maybe fri or sat I will do some work on equip.

[Les2]

Put two quick release valves on the trailer, one for each axle.

The only thing your doing with the chains is stopping the trailer from raising up real high giving you the impression your bags aren't getting over inflated, when in fact they still are!

[Kranky]

Put two quick release valves on the trailer, one for each axle.

The only thing your doing with the chains is stopping the trailer from raising up real high giving you the impression your bags aren't getting over inflated, when in fact they still are!

If the chains he installed are preventing the air bags from physically extending past their maximum rated height, then it would be physically impossible for the air bags to "Hyper extend".

As for being over inflated, the term "over inflated" means that the pressure is in excess of the air bag's rated P.S.I. capacity.

.

[Les2]

If the chains he installed are preventing the air bags from physically extending past their maximum rated height, then it would be physically impossible for the air bags to "Hyper extend".

As for being over inflated, the term "over inflated" means that the pressure is in excess of the air bag's rated P.S.I. capacity.

.

Guess you didn't get the point. Oh well not my bags or crossmembers getting beat up.

Although I do have one question...does anyone have an air gauge on their trailer? If so,, watch it when they pull a big coil off and let me know what the air pressure goes up to. I'm just curious as to if it goes up alot?

[Kranky]

Guess you didn't get the point. Oh well not my bags or crossmembers getting beat up.

Although I do have one question...does anyone have an air gauge on their trailer? If so,, watch it when they pull a big coil off and let me know what the air pressure goes up to. I'm just curious as to if it goes up alot?

When you suddenly take weight off an air suspension the air pressure in the air bags will drop, not rise, because the bags will extend further as the weight is removed, increasing the inside volume of the bags, and no more air is being introduced into the bags. At this point the ride height control valve has sensed an increase past the normal ride height and is actually exhausting air from the bags to bring the ride height back to normal.

But if the air suspension is "dumped" before unloading, hyper extension of air bags is a non issue.

[Les2]

When you suddenly take weight off an air suspension the air pressure in the air bags will drop, not rise, because the bags will extend further as the weight is removed, increasing the inside volume of the bags, and no more air is being introduced into the bags. At this point the ride height control valve has sensed an increase past the normal ride height and is actually exhausting air from the bags to bring the ride height back to normal.

But if the air suspension is "dumped" before unloading, hyper extension of air bags is a non issue.

Exactly! The airbag is rated to handle the air pressure thats in it even if its extended all the way. Now none of us like this to happen but the bag should still handle it.

Where I see people make mistakes is putting the bags on crooked or twisted and this can cause problems and a shortened life of the bag.

Like you said a dump valve is the best option. Or if you have a good leveling valve (not the cheap crappy plastic slow ones)and two quick release valves with 1/2" air lines, you can go without the dump valve and the airbags will last a long time.

[heavyhaulerss]

But if the air suspension is "dumped" before unloading, hyper extension of air bags is a non issue.

I have used the air dump. it does nothing for the axle that has no air dump. the axle with no air dump still raises the trailer & then lifts both axles up, stretching the all the air bags.

[heavyhaulerss]

I do have new, but cheap plastic leveling valve on trailer. it is what truckpro sold. if I can get a better one, that I knew for sure would work better I would. maybe for some reason the air is not being dumped quick enough. though I know this is not a prob that I just discovered, as I notice more & more flats, with the chains attatched.

[Kranky]

But if the air suspension is "dumped" before unloading, hyper extension of air bags is a non issue.

I have used the air dump. it does nothing for the axle that has no air dump. the axle with no air dump still raises the trailer & then lifts both axles up, stretching the all the air bags.

Then you should re configure your plumbing so you can dump the air from both axles while unloading.

We have some dump trailers with air ride where I work, and they are set up to dump the bags whenever the air operated tailgate is in the "open" position. Since the tailgate is opened when unloading, the air suspension is "automatically" dumped. (Unless the driver f's up and forgets to open the tailgate, but that's a whole 'nother set of problems if that happens.)
:eek2::whistle:

[allan5oh]

Are you sure the dump valve is just for one axle, or are you just not waiting long enough? Wait a good 30 seconds after dumping the air out and see what happens.

[Les2]

Then you should re configure your plumbing so you can dump the air from both axles while unloading.

We have some dump trailers with air ride where I work, and they are set up to dump the bags whenever the air operated tailgate is in the "open" position. Since the tailgate is opened when unloading, the air suspension is "automatically" dumped. (Unless the driver f's up and forgets to open the tailgate, but that's a whole 'nother set of problems if that happens.)
:eek2::whistle:

Yeah that usually involves a wrecker and some shovels...LOL

The reason I don't like the chain idea, sometimes chains and being your a steelhauler you've seen this, get all bound up and twisted. If that happens your not going to get prober ride height or you'll have the airbags pushing down and the chains holding it back.

[heavyhaulerss]

Are you sure the dump valve is just for one axle, or are you just not waiting long enough? Wait a good 30 seconds after dumping the air out and see what happens.
I am positive. air dumps only the front axle.

[allan5oh]

You could do something like this:

Drive the front axle onto some dunnage at the site where you want to unload. Make sure it is at least 4" high. Dump the front axle.

If the rear axle is still high with the front axle dumped, it will slowly come down. That should pretty much drain all the air.

Or just install a dump valve on the rear axle, or rework your current dump valve to dump both axles.

[Lngtaltxn]

Are you sure the dump valve is just for one axle, or are you just not waiting long enough? Wait a good 30 seconds after dumping the air out and see what happens.

Mine has a single dump valve for the rear, as do a lot of flatbedders I know. It is to reduce wear on the tires when turning

Lngtaltxn

[heavyhaulerss]

Well, I installed the new shocks today. though I was thinking as I bought them... I dont think they will help my over extension of my air bags. I just did not think of it before, but as I was bringing the new shocks home.. I realized that shocks stay extended out & have to be pushed in with some strength. it has been so long since I installed shocks that now I remember when buying them for my car 20 years ago, they would come with a wire attaching both ends to keep shock compressed. so since all the new shocks will be putting pressure upwards, I dont know how my problem will be solved by this install.

though I have no regrets about installing them. my ole ones were completely wore out. you could pull shock apart with ease & it would stay in the out position. or you could push all the way in with ease & it would stay in that position also. I got prices from $34.73 to $55.00 so for the $34.73 a piece it was worth it. & I installed myself. fleet pride had the best price. I am going to try & figure out how to post a pic here of one of the old shocks.

[heavyhaulerss]

thanks to all who chimed in on my behalf.

[heavyhaulerss]

oh and as far as the actual test.. I wont know for sure until I load again maybe tues or wed.

[allan5oh]

It's not that they will prevent outward expansion, but rather they have a limit on outward expansion.

[Kranky]

It's not that they will prevent outward expansion, but rather they have a limit on outward expansion.

Exactly.

The shock absorber should reach the end of it's travel before the air bag hyperextends.

Trouble is, I have seen shocks that snapped off because they couldn't handle the pressure, so the restraining chains are still not a bad idea.

.

[heavyhaulerss]

I.c. T.y.

[heavyhaulerss]

Exactly.

The shock absorber should reach the end of it's travel before the air bag hyperextends.

Trouble is, I have seen shocks that snapped off because they couldn't handle the pressure, so the restraining chains are still not a bad idea.

.

Exactly is right! the shocks were the problem. the new one's did the trick. while unloading, I watched & the chains did not have to hold the air bags from over stretching. the ride is much better too. when hitting dips & uneven pavement going down the hywy, the trailer does not give that ship on the sea's motion as it used to. a noticeable difference there too. thanks for the info.