Airing tires - air multiplier or compressor

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PancakeBill

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Benson - Tucson, AZ. West Yellowstone,MT
I wanted to add a little air the other day. I don't have a compressor, of course I have the onboard, but it does not do a great job of providing enough air, so what are the choices. My first is to get a Viair automatic, I have researched these and they seem to be a great accessory. I posted on another group and someone mentioned the Air multiplier or doubler. SMC is one of the manufacturers. This could be built in. but, I really don't know much about these. I see it as essentially getting the psi increased, but at what cost? PSI up and CFM down?

Another consideration is the portability of the Viair, can be used in may other areas, such as airing up afer Jeep run. Looks like cost is about the same, so not really a consideration.
 

HueyPilotVN

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I am surprised that you do not have enough pressure from the quick disconnect air supply under your front bumper on the drivers side. I always had plenty of air pressure from the one on my Country Coach.
 

thelazyl

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Molalla, Oregon
Do most Class A's with air brakes have a place to connect an external hose? I'm not I've found one on my 2003 Fleetwood (Freightliner) .. I've got a pancake compressor to carry with me but maybe I don't need it. I assume such a connection would be near my air tank?
 

HueyPilotVN

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Here is where mine were located. Each one had a shutoff valve.

Uses a regular air hose quick disconnect.
 

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Larry N.

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On my Beaver and on my Ventana, the quick connect was inside the generator door on the front (the Beaver had a second one in a storage bay, too), and both are adequate to pump up the tires. I also have the Viair 400 for use with the Jeep on 4WD trips, but it, too, can top off the tires on my rig, though I'd limit that to a top off -- volume is inadequate from very low pressure.
 

Gary RV_Wizard

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A Freightliner chassis definitely has an aux air port, usually located in the front left corner. Access varies by coach builder, either inside the front generator hole or the left-forward-most storage bay (under the driver). I think the Bounders typically placed it for use via the generator access door.
 

NY_Dutch

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Where our wheels take us!
Most air brake equipped vehicles have a quick-connect port somewhere that tow operators use to disengage the brakes for towing. It's a lot easier than crawling around caging the brakes. Especially in nasty weather conditions! Been there... ;)
 

Gary RV_Wizard

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I posted on another group and someone mentioned the Air multiplier or doubler. SMC is one of the manufacturers. This could be built in. but, I really don't know much about these. I see it as essentially getting the psi increased, but at what cost? PSI up and CFM down?
That's basically it, Bill. An air "booster" or "transformer" trades volume for pressure. No free lunch, but it can make the onboard compressor much more convenient for tire fills by getting the tank pressure well above what's in the tires. If you are topping up a tire that is only a few psi low, volume is not too important. If you were filling an empty tire from scratch, the reduction in volume would be a pain.

The operating range for most onboard compressors is roughly 90 psi-125 psi. If your tires need much more than about 100 psi, it can be difficult to add much air because tank pressure falls below 110 fairly quickly and not much air moves when the relative pressures get close like that. And of course, once the tank pressure drops below the tire pressure, air flows the opposite way.

 

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