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Air Hitch leveling valve?


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https://www.ebay.com/itm/Genuine-Volvo-Truck-20724370-Cab-Suspension-Leveling-Valve/123123921350?epid=1840391510&hash=item1caac1f1c6:g:7bYAAOSw7Kta8w8a&vxp=mtr is the valve.  Google it for cheaper prices.  Their usually $35 or so.

20 minutes ago, Pete Kildow said:

Will look into those, and the best way to hook it up.

 

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Colour me curious.  How much easier can it get than the oem valve that came with the hitch?  I just get out of the truck and hit the switch to dump the air to unhitch or hit the switch after hooking up to raise to ride height.  With the ride height valve mechanically connected to the bags how would you dump air to unhitch?  Just askin, not arguing!

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57 minutes ago, orca said:

Colour me curious.  How much easier can it get than the oem valve that came with the hitch?  I just get out of the truck and hit the switch to dump the air to unhitch or hit the switch after hooking up to raise to ride height.  With the ride height valve mechanically connected to the bags how would you dump air to unhitch?  Just askin, not arguing!

Orca- Right now with your hitch, Have you ever not lowered the air bags and pulled out from under the pin?  There is a really LOUD BANG when the back piece of the Trailersaver rapidly rises and smacks the pin....

I also have been known to hook up and be on the highway when I realize that I didn't/Haven't aired the hitch.

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2 hours ago, Alie&Jim's Carrilite said:

Orca- Right now with your hitch, Have you ever not lowered the air bags and pulled out from under the pin?  There is a really LOUD BANG when the back piece of the Trailersaver rapidly rises and smacks the pin....

I also have been known to hook up and be on the highway when I realize that I didn't/Haven't aired the hitch.

No, but not sayin it won't ever happen.  How would you drop the bags with a mechanical ride height valve? (just so's i unnerstand)

As for forgetting to air the bags on departure....been there done that.  If i opted for the fill valve to be incab i could have aired up on the fly by watching the guage but i opted for it to be in one of the storage boxes where there was already an air supply.

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21 minutes ago, orca said:

No, but not sayin it won't ever happen.  How would you drop the bags with a mechanical ride height valve? (just so's i unnerstand)

As for forgetting to air the bags on departure....been there done that.  If i opted for the fill valve to be incab i could have aired up on the fly by watching the guage but i opted for it to be in one of the storage boxes where there was already an air supply.

On my Volvo, I have 2 air switch dump valves that I can use. 

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19 hours ago, orca said:

Colour me curious.  How much easier can it get than the oem valve that came with the hitch?  I just get out of the truck and hit the switch to dump the air to unhitch or hit the switch after hooking up to raise to ride height.  With the ride height valve mechanically connected to the bags how would you dump air to unhitch?  Just askin, not arguing!

Orca, good question and fair question.

Jk2eT0Wl.jpg

ET hitches have leveling valve and were designed with one from day one (10 years ago). This has created two classes of people, "dumpers" and "non-dumpers", the non-dumpers being the ET owners. I have to spend considerable time with new ET owners to undo the dumper instincts, they are "powerful". Unfortunately there is no patch to deal with that addiction.

The non-dumper technique is pretty simple and "gentle" on the truck and trailer.

When positioned and ready to unhitch lower the fifth's jacks until they come in firm contact with the ground. 

Lower the jacks (raise the fifth) a little more (1/4 inch or so) and listen to air hissing. The sources of that high pressurized air are twofold, the hitch suspension (air bags) and the truck suspension (air bags),  after a minute or two the hissing will stop.

Raise the fifth another 1/4 inch and listen to the hissing air again, you might have to do it 2-3 times until the last time you raise the fifth you will hear no hissing and you will observe the the king plate has slightly separated itself from the top of the hitch head (there is a slight gap).

Open the jaws on the head and drive off☺️

You have just joined the ranks of "non-dumpers"

The whole concept involved here is this. By slightly raising the fifth you are removing the weight from both, the hitch and the truck, therefore both dump the air (automatically) to reach the "new" equilibrium (in the hitch and on the truck). By repeating this you eventually reach the point where there is no weight (from the fifth) on both the hitch and the truck. At that point there still will pressurized air in the hitch and in the truck but only enough to keep the truck and hitch level and not supporting the fifth any more. Therefore nothing will "jump up"  when you drive off.

In my earlier post I mentioned the design of the bracket which you need to hold and position the valve, you see one holding the air valve in the above picture. Its height and location is not arbitrary for the system to work properly, quite a bit of thought went into this simple bracket.

Edited by phoenix2013
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Hi Henry -  I'm a "non-dumper" but with a twist.   I would like to dump the sled so it clears the Mini Cooper (with margin) when I get it down off the truck.  With the sled aired up, I need a spotter to make sure the head doesn't snag on something under the car.   With the sled dumped, no spotter required.  I while back I sent you a cut sheet for a three way ball valve that would allow for said dumpage and undumpage by venting the bags while blocking the signal from the leveling valve.  Have you designed a dumpage system with a ball valve?

thx

Rich

 

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Henry;      thanks for the explanation that i can understand.  The routine i follow is close to yours but i manualy dump my hitch bags but as i drop my landing legs i wait for the truck suspention to adjust for the reduced weight. Same but different! 

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Rich, I have the info and I've modified few ETs so that its airbags can be dumped and thus provide additional 3 inches of clearance for anything that needs to go over the hitch. But such as yours it is not a common requirement, most things are loaded from the side.

Orca, your approach is the correct way to unhitch an air hitch without a leveling valve. When I designed an ET I thought that the hitch could work  simultaneously and in the same manner as the truck suspension and require no adjustments regardless of the pin weight or cargo loading. After all, truckers don't have to fool around with the suspension, they hitch up whatever they have to hitch up to and go.

An air hitch will have several thousands pounds of pressure in the air bags while operating (the pin weight), bad things happen if you drive off with all that pressure still in the air bags.

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6 hours ago, phoenix2013 said:

An air hitch will have several thousands pounds of pressure in the air bags while operating (the pin weight), bad things happen if you drive off with all that pressure still in the air bags.

Dang Henry, I had to read that three times before I realized you really meant what you wrote, but my eyes were reading "several thousand psi".  Duh......

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As an engineer I should have known to be more precise and should have said "several thousands pounds of FORCE"

It's a fact that the air molecules, oxygen, nitrogen and their lesser cousins are an unfriendly bunch that hate confinement, sort of like folks who hate cities and have to move out to their acre size house lots in suburbs. If you force more of them to live together into a confined space (an air bag), they get very bitchy and start elbowing each other big times, hence the force proportional to the pressure.

That's my best description without getting into Boyle's law, Charles' law, etc.

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What can I say, Just lazy. And  would rather not have to air up the hitch each time. When I can mount a valve, let it do its job. And will tie it into the airbag dump valve on the truck. One dump valve switch for both.

Some days I may swap out my trailers 2 or 3 times. And that is the main reason for looking into a leveling valve.

 

Thanks for the links guys.

Edited by Pete Kildow
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