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Author Topic: One fill point or two fill points?  (Read 502 times)

Bigmau

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One fill point or two fill points?
« on: February 10, 2019, 10:07:52 AM »
Recently, I had both air bags and associated lines replaced. One had a leak and the tech suggesting replacing both, under warranty. I asked if I could have one fill point for both. The tech did not recommend saying that if there is a leak, they will both go down. So, two fill points.
I though about that and if one leaks, then you'll driving down the road at a slight angle and surely it will affect the handling of the RV. Having one fill point and there is a leak, they will both leak equally and keep your vehicle straight although no as smooth as it should be.
What are the pro/con of one vs two fill points?/

Kevin Means

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Re: One fill point or two fill points?
« Reply #1 on: February 10, 2019, 11:04:37 AM »
I am going to assume that you're talking about Firestone Ride-Rite air bags, or a similar product. We had them on the rear of our previous coach, and they worked well. The air pressure in each bag could be individually adjusted with a dual-switch setup under the dash that controlled a 12 volt air pump. Our coach had a slight lean to one side, and raising the air pressure slightly on the low side helped... a little, but it also made the ride stiffer on that side.

Kev
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Bigmau

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Re: One fill point or two fill points?
« Reply #2 on: February 10, 2019, 11:17:58 AM »
Kevin, you may had a sophisticated system with built in pump and gauges so you can monitor at a glance. I don't have that. Just a fill point for each bag located on opposite storage compartment, so not as convenient.

nibroc

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Re: One fill point or two fill points?
« Reply #3 on: February 10, 2019, 12:29:53 PM »
my air bags have separate fittings on each side----no problem

lynnmor

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Re: One fill point or two fill points?
« Reply #4 on: February 10, 2019, 03:49:13 PM »
One fill point is more convenient.  There is a minor downside to having the bags linked together in that air will travel from the one becoming more loaded, such as a tilted road or sharp curve, causing more lean.

Old_Crow

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Re: One fill point or two fill points?
« Reply #5 on: February 11, 2019, 06:42:21 AM »
One fill point is more convenient.  There is a minor downside to having the bags linked together in that air will travel from the one becoming more loaded, such as a tilted road or sharp curve, causing more lean.

This makes sense.  This is similar to the front leveling jacks on my coach that are tied together with one hydraulic line.  You put them down first and then the coach rocks one way or another on those jacks as you level the coach with the rear jacks.  Not uncommon for me to see one front jack extended 2 or 3 inches more than the other., even though they extended together initially.

If part of the purpose of the air bags is to control lean, you're better off with separate fill points so the compressed air can't transfer from one bag to the other during a turn.
Wally Crow
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Bigmau

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Re: One fill point or two fill points?
« Reply #6 on: February 11, 2019, 07:07:58 AM »
I’ve been reading all the above replies. With any vehicle, isn’t true that when engaging a turn at highway speed, your vehicle will put more pressure on the outside of the turn? Highway being constructed as they are, turns are always slightly leaning toward the inside as to help keep your vehicle somewhat leveled during the turn. So, by having air bags connected, you will put more pressure on the outside thus adding pressure to the opposite bag and help keeping your vehicle somewhat straight and having the suspension the do the flexing. Or may be, this doesn’t apply to large vehicles like an RV?
Just wondering…

SargeW

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Re: One fill point or two fill points?
« Reply #7 on: February 11, 2019, 09:31:15 AM »
What you are describing is the way that most MH builders set up the air bag systems on RV's.  IE the air bag system is designed to allow air to flow back and forth at a controlled rate between the air bags to assist with lean when a coach encounters an off camber turn or angled drive way.  In my coach the builder has a 12 volt air system that monitors the lean and the air pump will add or subtract air automatically if a lean is detected while moving or parked.

There are such devices called "Motion Control Units" that is an after market device. They are installed by cutting the air line between air bags and installing them in line. They allow a faster transfer of air between the bags and thus claiming to keep the coach "more level" when encountering a significantly sloped driveway or road. 

They can however degrade overall ride of the rig by allowing the rig to react to regular roadway seams and potholes. So it's a trade off on what the driver prefers.  (like most things).
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Joezeppy

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Re: One fill point or two fill points?
« Reply #8 on: February 11, 2019, 09:44:22 AM »
Not motorhome related but when I had airbags on my Silverado 1500 I routed the hoses both to one side for convenient filling.
Joe & Kim
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Broke Boater

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Re: One fill point or two fill points?
« Reply #9 on: February 11, 2019, 12:21:07 PM »
I installed air bags before I installed the sway bar on my 1 ton dually to level rear to front with a 5k lb camper on it. Love the air bags, so much smother ride getting the truck of its over loads. I have one fill spot for both bags. The sway bar did a great job controlling sway traveling on the road, the bags really didn't help at all for sway. I would not want one corner off the overloads and one side still under assist of the bag on a trip. I would rather have both sides even, especially if I was on a curvy road/hwy. Side to side sway is better handled by a sway bar vs air bags. Off point is the ideal is a elec. over hyd. system designed for handling. Pneumatic with bags would be to slow to effectively react to a vehicle traveling at speed and changing road conditions. If your two points of fill are next to each other, then it not that big of a deal other then having to check two points for pressure and leveling it out,,,gregg
2012 Dodge Ram 3500 4x4 Dually crew cab 6.7 cummins
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Bigmau

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Re: One fill point or two fill points?
« Reply #10 on: February 11, 2019, 01:28:30 PM »
Thanks all. Leaving for a short camping trip tomorrow and on my return, I will re-route the air lines to one filling point using a T connector. I will post any finding after that. If feasible, I'm also thinking of installing a permanently mounted pressure gauge near the fill valve if that is possible. Any idea what type I can install?

Broke Boater

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Re: One fill point or two fill points?
« Reply #11 on: February 11, 2019, 02:19:30 PM »
Short of having one mounted inside the truck to check pressure, I just have a hand held in the console. The pressure holds for weeks and then its only a small loss. Less connections=less loss.  A complete onboard system is on the bucket list
2012 Dodge Ram 3500 4x4 Dually crew cab 6.7 cummins
2011 Artic Fox 992
24' Skipjack custom Pilothouse,, F/V Valhalla


early bird gets the worm, second mouse gets the cheese