Compressed Air Outlet

VerMonsterRV

Gotta Be Nuts
So in my ever so slow learning of our truck I now realize Mercedes included a tire inflation port as standard. Included with the truck when new was an inflation hose, but we didn't get it when we bought our truck. Now looking at the manual this factory original hose screws onto a rubber capped port. If we only had a single rubber capped port this would be obvious, but we have several. One of the ports is after the unloader valve, which seems odd and is where I am currently tapped into. Would anyone know the proper port to use? After the unloader is odd because once the truck compressor reaches 8 bar then no pressure after the unloader. Would have pump to pump the brakes to close the unloader. Which strangely enough the manual mentions doing that to drop the pressure to 6 bar prior to filling tires.
 

VerMonsterRV

Gotta Be Nuts
From our manual

5.7.5 Tire inflation connection The tire inflation connection is on the front of the pressure regulator. Remove the protective cap for the tire seal and connect the tire inflation hose. Lower the supply pressure in the compressed air system to approx. 6 bar, e.g. B. by pressing the service brake several times. Start the motor. Max. Air pressure for tire inflation 10 bar. FG 21 819
 

Sitec

Adventurer
I don't know where the port is, but there's another way of doing it... Put a Tee in one of the main tank outlets and get your supply from there. If you find the right tank, it can be used the other way around in that if the motor is dead, another truck can hook up, charge your air system, and allow your truck to be towed. Recovery guys love this option. We have a Nito male and female connection point on our main air tank with a tap between them so you can feed in, or supply out. You than carry an air line that reaches all corners of the truck. :)
 

Neil

Observer
I always take the air from this union, under the rubber dust cover. You can get a screw on connector that only needs to be hand tight.

Neil

20210127_234755.jpg
 
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Geo.Lander

Well-known member
we have the tire inflation outlet but I cannot at the moment get better pictures of where i is connected (the truck is out of our county line and our lockdown is restricting travel). I do remember it was installed with a brass T junction but do not know anything more than that, below is he outlet for the tire inflation before the firetruck box was removed..
Screenshot 2021-01-02 at 11.22.07.png
 

VerMonsterRV

Gotta Be Nuts
Hey @Geo.Lander (Dimitri), thanks for the picture. It triggered a memory from a couple of years ago that we had the exact same air outlet in the same position on our firebox. Now thinking about it the source for that outlet is now the one I have plumbed to our DC onboard air tank. So, for ours the firebox body builder followed Mercedes instruction (well at least what my manual says to do) and installed the tire inflation air tap after the unloader valve. So in order to use it you need to drop the air pressure in the truck air system below 8 bar in order to get the air to flow to this.

I always take the air from this union, under the rubber dust cover. You can get a screw on connector tgst only needs to be hand tight.
Thanks @Neil, I will look into getting one of these hoses. I have not found any in North America (the fitting with the ears for connecting to the tap) so will have to wait for a shipment from Europe. Will have to wait till we get back from Mexico as with any luck we will get this welding finished and on our way south. Heck, it snowed here Tuesday, yeah snowed in Tuscon!
 

Geo.Lander

Well-known member
Hey @Geo.Lander (Dimitri), thanks for the picture. It triggered a memory from a couple of years ago that we had the exact same air outlet in the same position on our firebox. Now thinking about it the source for that outlet is now the one I have plumbed to our DC onboard air tank. So, for ours the firebox body builder followed Mercedes instruction (well at least what my manual says to do) and installed the tire inflation air tap after the unloader valve. So in order to use it you need to drop the air pressure in the truck air system below 8 bar in order to get the air to flow to this.


Thanks @Neil, I will look into getting one of these hoses. I have not found any in North America (the fitting with the ears for connecting to the tap) so will have to wait for a shipment from Europe. Will have to wait till we get back from Mexico as with any luck we will get this welding finished and on our way south. Heck, it snowed here Tuesday, yeah snowed in Tuscon!

In my quest to design a home brew STIS I have found regulator values readily available, I know you said you had sourced some as well but why not simply plug into the mains so to speak and use a value to regulate pressure output?
Festo in the EU seems to be a main brand name, not too expensive either..
Screenshot 2021-01-28 at 16.50.29.png
 

VerMonsterRV

Gotta Be Nuts
For us, due to the difference in axle weight we are now running lower pressure in the front. So something with a gauge and adjustment would be nice. Also looking into the "auto inflators". Set the desired. Pressure and walk away. Not too expensive and seems like a happy medium.
 

Joe917

Explorer
The time limiting factor is compressor volume/speed. For the number of times we air down pumping each tire one after the other is not a big deal. I have enough trouble keeping one inflator hose from tying everything in the storage together without adding an auto inflator set of hoses.
 

Neil

Observer
Thanks @Neil, I will look into getting one of these hoses. I have not found any in North America (the fitting with the ears for connecting to the tap)

Do you have the outlet like that on your vehicle , is it just the winged connection you need or the whole fitting

Neil
 

VerMonsterRV

Gotta Be Nuts
Do you have the outlet like that on your vehicle , is it just the winged connection you need or the whole fitting

Neil
Hey, on our truck there are at least 4 of those fittings beneath the rubber cap installed. Have read they are air system test ports. I see online there is an air hose with a fitting on the end with "wings" that allows you to screw it on without tools. The wing bit is what I will order, but I will probably wait till we return from Mexico. My current setup will work, just thought it'd be good to get the factory hose/fitting.

Oh, with any luck we will be heading to Mexico on about a week, for a couple of months. Gotta test out the new lights ?.
 

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