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Old 05-20-2019, 12:59 PM   #1
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Air bags, adjusting for variable TV bed loads

I have read many of the threads and watched the convincing video on why weight distribution is a far superior solution to airbags when towing:

The issue is presented as WD or Airbags whereas this post is about WD and Airbags to maintain the AS level.

When we leave for short trips, the towing vehicle is generally lightly loaded (config 1). When we leave for multi-month trips where we must be prepared for varying (sometimes extreme) weather conditions, for long boondocking periods, for kayaking (inflatable), biking (folding), etc., the TV is more heavily loaded (config 2).

Even if we make sure that with the TT hitched and weight distributed we never exceed the manufacturer’s weight specs (gross, axel, etc.), with different TV bed loads, the hitch head ground height will invariably change, whereas the tongue weight of the AS is pretty much stable. The result is that the level of the AS will change.

I have an Equalizer WD hitch with 1200# bars, and have never had any sway of any kind in all kinds of conditions (high winds, highways, mountains, etc.). Beyond changing the height of the L brackets on the TT and the position of the hitch head/ball on the TV, weight distribution is adjusted by the angle of the hitch head to which the WD bars are attached. The lower the angle, the more pressure the WD bars will apply to the L brackets thereby transferring more weight to the TV and increasing the friction between the bars and the L brackets, resulting in more sway control. The angle of the hitch head is adjusted by adding or removing washers within the head; which is not something you do without the heavy duty tools for unbolting, bolting, torquing, etc.

If I adjust my weight distribution hitch setup with a lightly loaded TV (config 1) for a proper distribution of TT weight to the front axle of my truck and maintain the AS level, is there a problem of using rear airbags to maintain the hitch head/TV in that exact same position (same ground height) when the TV truck bed is more heavily loaded (config 2)?

Since the airbags will maintain the height of the hitch head from the ground, my WD bars will be applying the same pressure from the AS onto the L brackets, and will be transferring the same amount of TT weight to the front axle. It is the rear axle which will have more weight to carry, but if it is well within manufacturer’s specs, is there a problem?

Re-adjusting the WD setup every time the load in the TV changes in order to maintain the AS level, is not an option, at least not with the hitch I have.

Is anybody applying proper weight distribution as well as using airbags to compensate for varying TV bed loads to maintain the AS level?
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Old 05-20-2019, 04:58 PM   #2
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I have always used WD to level for varying loads...👍
IMO aftermarket AB's contribute nothing to improve towing.

Bob
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Old 05-22-2019, 07:45 AM   #3
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While air bags won't do anything to distribute weight they can be useful to level your trailer after you have adjusted your hitch to give you the weight distribution you want across the tow vehicle's axles. It is important to tow a level trailer if you trailer has tandem axles. If you are too low in the front then your front trailer tires will get too much load and your rear tires not enough. If you are too high in the front then vice versa. If after adjusting the weight distribution hitch your trailer is not level then you can level it in two ways: Adjust the hitch shank (not easy) or adjust the air bag leveling system (easy).
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Old 05-22-2019, 08:58 AM   #4
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I called the customer support folks at Equalizer in Provo Utah and they confirmed that the hitch's effectiveness (WD and sway control) is affected by the variation in the vertical displacement of the hitch/ball from the ground (due to a variation of the TV load for example) and the by TT tongue weight (which shouldn't vary all that much, except for the changing weight of the propane tanks).

If airbags are used to keep the hitch head/ball at a constant distance from the ground (thereby keeping the AS level), no matter the TV load, then the hitch will operate as intended and as dialed in. They said that many of their customers use airbags for this purpose without any problems.
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Old 05-22-2019, 04:16 PM   #5
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So, explain how that works...do you level with WD and then level more with bags? Exactly what condition are you correcting with the AB's?

We use the proper drop stinger...ie, un-hitched AS level and the ball height matches the AS coupler.
Drop the AS on the ball, the rear of the TV drops, and WD is used to raise the TV rear and restore front axle weight, the rig is level again.

No bags necessary...could it be the design of your hitch? That could be why the CS folks see no problem.

Bob
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Old 05-23-2019, 05:50 PM   #6
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In a nutshell, the airbags are used to make a height adjustment of the tongue/ball once the AS is hitched with WD applied.

The reason is that WD bars may not be able to maintain the AS level from one trip to the next, depending on the load in the TV. And with an Equalizer hitch (and others based on the same system combining WD and sway control) you don't have chain links to play with.

The procedure then is set up the hitch so that the AS is level and WD properly dialed in (which can be validated with a visit to the CAT scale), then measure the vertical height of the hitched tongue/ball from the ground. This becomes the "reference" height which will be kept constant, no matter the TV bed load.

Thereafter, whenever you hitch up the trailer, you check the height of the tongue/ball and, if necessary, use the airbags to adjust to the reference height, thereby ensuring that the AS is always perfectly level and WD is properly applied (but make sure you don't exceed the rear axle max load specs -- airbags don't increase the load capacity of the TV).

With an Airlift onboard compressor there is a remote control which you use to raise or lower the TV bed (ie. increase or decrease pressure in the bags) and automatically maintain that level. So in a few seconds all is set without needing to re-adjust WD (which would be a PIA with an Equalizer type hitch).
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Old 05-23-2019, 06:36 PM   #7
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Count me as an airbag skeptic. WD hitches distribute weight through a torque or bending moment toward the front of the TV. For a given setup, the amount of torque increases as the ball drops further. If you set up the WD hitch for proper weight distribution, then raise the ball with airbags, you’re defeating (at least partly) the function of the WD Hitch.
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Old 05-23-2019, 07:27 PM   #8
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Quote:
Originally Posted by KK4YZ View Post
Count me as an airbag skeptic. WD hitches distribute weight through a torque or bending moment toward the front of the TV. For a given setup, the amount of torque increases as the ball drops further. If you set up the WD hitch for proper weight distribution, then raise the ball with airbags, you’re defeating (at least partly) the function of the WD Hitch.
Exactly...if you must use AB's along with WD there is something wrong with your hitch or set-up.
I lean toward a hitch that is not up to the task'

If you are using the proper drop stinger, along with properly rated WD bars there is no need for add-on bags.
But it is your rig...do as you please.😂

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Old 05-23-2019, 10:29 PM   #9
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I have both. The bags have a remote so I can make adjustments while rolling if needed. I also have a steep transition from my driveway to the road, adjusting the bags makes the difference between scraping or not. Inflating / deflating has kept the trailer from scraping at gas stations and camp sites as well. Others have said it’s overkill, but if I were a skydiver, I’d probably be the one with a second parachute...overkill shmoverkill.



-Sean-
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Old 05-24-2019, 12:02 AM   #10
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Hi, I towed my trailer for over ten years with my Lincoln Navigator and an Equal-I-zer brand hitch. My Lincoln is two wheel drive and only has [self leveling] rear air bags, no metal springs. No problem what so ever.

I now tow my trailer with a 2014 F-150. Same hitch with different shank. Both set ups for the Lincoln and my F-150 worked best with 6 1/2 washers. Loads vary slightly, but no changes are needed or necessary.
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Old 05-24-2019, 06:10 AM   #11
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Quote:
Originally Posted by ROBERTSUNRUS View Post
Hi, I towed my trailer for over ten years with my Lincoln Navigator and an Equal-I-zer brand hitch. My Lincoln is two wheel drive and only has [self leveling] rear air bags, no metal springs. No problem what so ever.

I now tow my trailer with a 2014 F-150. Same hitch with different shank. Both set ups for the Lincoln and my F-150 worked best with 6 1/2 washers. Loads vary slightly, but no changes are needed or necessary.
Bob.

Your Lincoln had factory Air Suspension correct?
Did you set your WD with the self leveling disabled?
Not the quite same as bags added to springs...🥴

Bob
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Old 05-24-2019, 10:38 PM   #12
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Bob.

Your Lincoln had factory Air Suspension correct?
Did you set your WD with the self leveling disabled?
Not the quite same as bags added to springs...��

Bob
����
Hi, Yes, originally. My owner's manual tells you how to set up a WD hitch with factory air suspension.
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Old 05-24-2019, 11:42 PM   #13
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I have both airbags and a Blue Ox EQ hitch with 1,000lb bars adjusted on a CAT scale being towed by a F150. All I know is the rig porpoises a bit with the air bags deflated but that goes away with them at 45lbs. My theory is the F150 stock suspension was tuned to give a nice car-like ride when unloaded but when it’s loaded near payload capacity the airbags help provide some extra support.

All passive suspension systems are a compromise between ride comfort and payload capacity. A higher end WD hitch and better shocks might have solved this but since my truck already had air bags that was the easy solution for me.
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Old 05-25-2019, 07:20 AM   #14
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Quote:
Originally Posted by SeanWasHere View Post
I have both. The bags have a remote so I can make adjustments while rolling if needed. I also have a steep transition from my driveway to the road, adjusting the bags makes the difference between scraping or not. Inflating / deflating has kept the trailer from scraping at gas stations and camp sites as well. Others have said it’s overkill, but if I were a skydiver, I’d probably be the one with a second parachute...overkill shmoverkill.



-Sean-
Yeah, adjusting for steep transitions makes sense. I’m just skeptical about using bags as a partial replacement for WD adjustments.
Thanks for the input.
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Old 05-25-2019, 09:19 AM   #15
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Two different tools.

While airbags may level the rear suspension, in towing, their primary benefit is to increase the spring rate to better manage heavy loads.

Weight distribution can also level the rear suspension. But it's primary task is to distribute weight to the other axles, including returning some weight back to the trailers axles.


There is a critical negative interaction between the two that one has to be aware of when utilizing both.


It is critically important to set the WD tension after setting airbag pressure. And then never inflate the bags to a pressure higher than that calibration.

Doing it the other way around or over-inflating the airbags will effectively reduce and negate WD tension and distribution. Over-inflating has the same effect of jacking the hitch with the tongue jack. We all know that jacking up will relieve WD bar pressure, reducing front axle weight restoration (FALR) and stability benefits of the WD hitch.
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