Load Equalizing hitches

[PJohnson]

Originally Posted by dznf0g

SEC,
Just looked it up for a Silverado, just as an example:
Max payload:
"1/2 ton" 1980#
"3/4 ton" 4192#
"1 ton" 6635#

Wow! More than 2 tons for a "3/4 ton" pickup. Maybe I should have gotten a Silverado. My 2008 Dodge Ram 2500 HD is supposed to be a heavy duty 3/4 ton pickup and it's payload capacity is only 1850 lbs.

As for a "soft" ride, with the trailer (790 lbs tongue weight) the dogs, canopy, generator, etc., if I do not use weight distrubution the "load" causes the truck to be very close to riding on the overload springs and it is definitely not a "soft" ride.

[dznf0g]

Originally Posted by PJohnson

Wow! More than 2 tons for a "3/4 ton" pickup. Maybe I should have gotten a Silverado. My 2008 Dodge Ram 2500 HD is supposed to be a heavy duty 3/4 ton pickup and it's payload capacity is only 1850 lbs.

As for a "soft" ride, with the trailer (790 lbs tongue weight) the dogs, canopy, generator, etc., if I do not use weight distrubution the "load" causes the truck to be very close to riding on the overload springs and it is definitely not a "soft" ride.

Not sure why...Dodge lists 2010 specs on website???

MAX payloads

1/2 ton 1900#
3/4 ton 3160#
1 ton 5130#

[dznf0g]

Andy,

I am certainly not being negative at all, and as I expressed above, I am very appreciative of your efforts. I have read through ALL the prior "stuff" and have a very technical background, but I'm still stuck.

I understand the uniqueness of the AS construction and it's strengths and weaknesses.

I will be in the market for a TV sometime (OK when funds become available).

I am really interested in your findings because I like the ride and behavior of a half ton suspension with a "stiff" bar. Equal-i-zer with 1000# bars (Per scales I'm at 900# tongue weight)
I know I am good relative to GAWRs, GVWR, but am over on GCWR. That means powertrain and braking are underspec'ed for my trailer.

With a softer truck suspension and "stiffer" bars, the truck front suspension will take quite a bit of the stress off the trailer frame tongue when entering a sharp drive, etc. How much? I don't know. Same scenerio with a 3/4 or one ton...not as much compression of front suspension and more stress on the tongue. In this scenerio....softer equalizing bars are in order????

This is the reason I was asking about spring bar deflection rates with various truck configurations. No negtivity meant at all.

What I really want is a truck with a 1/2 ton suspension and 3/4 ton brakes and powertrain. (NO! I'm not going to start modifying suspensions to this degree! Not safe without the level of OEM testing)

The Yukon XL I picked up for my new company car comes close on the powertrain side, but brakes are 1/2 ton components. I'll still be over on GCWR.

[PJohnson]

Originally Posted by dznf0g

Not sure why...Dodge lists 2010 specs on website???

MAX payloads

1/2 ton 1900#
3/4 ton 3160#
1 ton 5130#

The problem with these numnbers is that they are for a 2WD short bed with a regular cab and a gasoline engine. If you have a long bed, the numbers go down. If you have a quad cab the numbers go down. If you have a diesel, the numbers go down. If you have 4WD, the numbers go down. If you have all of these options, the numbers go way down. The only reliable number concerning payload capacity is the number on the door post of the truck you own or are buying.

Then there is the problem of the trailer hitch weight. Weight behind the rear axle adds more weight to the rear axle than just the absolute weight. The reason for this is that the lever action of the weight behind the rear axle takes weight off the front axle and this weight is then added to the weight on the rear axle. The result is that the truck has even less payload capacity because loading it to the payload capacity will overload the rear axle.

The function of weight distrubution is, at a minimum, to transfer the weight removed from the front axle (resulting from weight behind the rear axle) back to the front axle. As others have stated, payload capacity assumes that the weight will be distributed BETWEEN the axles.

Therefore, we really need to know what the weight capacity of the axles are and to make sure that we are not overloading the axles!

[dznf0g]

Originally Posted by PJohnson

The problem with these numnbers is that they are for a 2WD short bed with a regular cab and a gasoline engine. If you have a long bed, the numbers go down. If you have a quad cab the numbers go down. If you have a diesel, the numbers go down. If you have 4WD, the numbers go down. If you have all of these options, the numbers go way down. The only reliable number concerning payload capacity is the number on the door post of the truck you own or are buying.

Then there is the problem of the trailer hitch weight. Weight behind the rear axle adds more weight to the rear axle than just the absolute weight. The reason for this is that the lever action of the weight behind the rear axle takes weight off the front axle and this weight is then added to the weight on the rear axle. The result is that the truck has even less payload capacity because loading it to the payload capacity will overload the rear axle.


The function of weight distrubution is, at a minimum, to transfer the weight removed from the front axle (resulting from weight behind the rear axle) back to the front axle. As others have stated, payload capacity assumes that the weight will be distributed BETWEEN the axles.

Therefore, we really need to know what the weight capacity of the axles are and to make sure that we are not overloading the axles!

I understand. As I stated in both posts, these are MAX figures from both MFRs. (you know with all the little footnotes relative to engines, transmissions, axle ratios, options, suspension options, etc.) Apples to apples, they are MAX figures.

[PJohnson]

Originally Posted by dznf0g

I understand. As I stated in both posts, these are MAX figures from both MFRs. (you know with all the little footnotes relative to engines, transmissions, axle ratios, options, suspension options, etc.) Apples to apples, they are MAX figures.

The point that I was trying to make is the "MAX" weight carrying capacity(advertised by the manufacturer) doesn't have much relavence to the real world.

[Topshelf]

Originally Posted by dznf0g

Andy,

I am certainly not being negative at all, and as I expressed above, I am very appreciative of your efforts. I have read through ALL the prior "stuff" and have a very technical background, but I'm still stuck.

I understand the uniqueness of the AS construction and it's strengths and weaknesses.

I will be in the market for a TV sometime (OK when funds become available).

I am really interested in your findings because I like the ride and behavior of a half ton suspension with a "stiff" bar. Equal-i-zer with 1000# bars (Per scales I'm at 900# tongue weight)
I know I am good relative to GAWRs, GVWR, but am over on GCWR. That means powertrain and braking are underspec'ed for my trailer.

With a softer truck suspension and "stiffer" bars, the truck front suspension will take quite a bit of the stress off the trailer frame tongue when entering a sharp drive, etc. How much? I don't know. Same scenerio with a 3/4 or one ton...not as much compression of front suspension and more stress on the tongue. In this scenerio....softer equalizing bars are in order????

This is the reason I was asking about spring bar deflection rates with various truck configurations. No negtivity meant at all.

What I really want is a truck with a 1/2 ton suspension and 3/4 ton brakes and powertrain. (NO! I'm not going to start modifying suspensions to this degree! Not safe without the level of OEM testing)

The Yukon XL I picked up for my new company car comes close on the powertrain side, but brakes are 1/2 ton components. I'll still be over on GCWR.

Have you checked the Chevy or GMC 1/2 ton with the max-tow package? It comes with 6.2L engine, 403 hp. speed auto trans with real nice low 1st gear, 4 wheel disc brakes, (not on regular 1/2 ton), larger diameter ring gear with stronger housing, all cooling upgrades (eng and trans oil), plus a lot more. Also recommend factory brake controller.

[dznf0g]

Originally Posted by Topshelf

Have you checked the Chevy or GMC 1/2 ton with the max-tow package? It comes with 6.2L engine, 403 hp. speed auto trans with real nice low 1st gear, 4 wheel disc brakes, (not on regular 1/2 ton), larger diameter ring gear with stronger housing, all cooling upgrades (eng and trans oil), plus a lot more. Also recommend factory brake controller.

Yes, I believe I'd still be about 1000# over GCWR. We should probably take these posts out of Andy's hitch trial thread. I think we have hijacked enough. Moderator: what think you?

[Gene]

I am curious how these tests are being conducted and by whom. To insure accurate and unbiased results, it would be best done by a research lab. No doubt no matter who does what, the results will be questioned and criticized, but by having an independent lab do it, the criticism may be less noisy. After that, what will it mean?

I recall a series of articles in Airstream Life which included information about deflection in bars. I can't say I understood a lot in the articles.

Gene

[Jammer]

Andy,

I look forward to the publication of results.

Originally Posted by CrawfordGene

I am curious how these tests are being conducted and by whom. To insure accurate and unbiased results, it would be best done by a research lab. No doubt no matter who does what, the results will be questioned and criticized, but by having an independent lab do it, the criticism may be less noisy. After that, what will it mean?

Gene,

The true test of such research is whether the results are repeatable.

Should Andy's results be at odds with our expectations there is always the possibility of re-running the tests. It is not difficult to do, merely time consuming, and requiring access to a platform scale and suitable lifting equipment.

[Topshelf]

Originally Posted by CrawfordGene

I am curious how these tests are being conducted and by whom. To insure accurate and unbiased results, it would be best done by a research lab. No doubt no matter who does what, the results will be questioned and criticized, but by having an independent lab do it, the criticism may be less noisy. After that, what will it mean?

I recall a series of articles in Airstream Life which included information about deflection in bars. I can't say I understood a lot in the articles.

Gene

Everyone is not going to agree with the results of any test regardless of who conducts it. I do believe Andy will give the most unbiased, professional results that will ever be on this site. I am looking forward to seeing the results.

[dznf0g]

Here's what I hope to gleen from Andy's tests (among other things):

I have always been confused what the bar ratings mean. Does 1000# mean the bars a capable of handling 1000#s of tongue weight (max) throughout the operating range (Difference in attitude or angle between the TV and AS, like a steep approach angle)? Whatever that operating range might be...no one can tell me.

Or, does 1000# rating mean that the bars are capable of 1000#s of force on their tip, at max operating range (deflection), before they potentially yield and deform?

I have had this discussion with the folks at Equal-i-zer and we went 'roud and 'round the mulberry bush! (not sure if I'm the monkey or the weesle).

I also wonder at what force 30" rearward of the ball socket (point at thich the "L" brackets mount) would be required before my A-frame yields. Not gonna get that answer, I fear.

[toastie]

Originally Posted by newroswell

It appears that Andy is testing various brands & styles of bars, for their rated spring rate vs actual spring rate. I doubt his test procedure will even include a tow vehicle, which would only cloud the results. It would be up to us to take the actual brand/style WD hitch spring rate into account in tuning our towing setup.

Until now the notion that round bars are softer than square bars has been measured by the seat of pants method, which sometimes can be accurate "enough". I want to thank Andy up front for undertaking this work, and I'm looking forward to the results.

I agree with you, just various brands & styles of bars. Nothing like taken a random new part that just came off the manufacture ass'y line and doing a real test, nothing better. The manufactures of these bars do there analysis, build in a safety factor then test them. If the test numbers agree with the analysis that is what will appear on there detailed drawings, hoping that there detailed drawing never appears in a court room of law. I also want to thank Andy up front for undertaking this work, and I'm looking forward to the results.........You rock Andy.

toastie


toastie

[safari57]

Thank you for doing this Andy, and for being willing to share your results.

What ever they are, they will at least be based on actuall tests versus the wet-thumb in the air/best guess we usually have to rely on.

A little Christmas gift for those of us on the forum is it? Regardless, it is very much appreciated.

[Journalist]

This should be interesting. I'm really interested to see some comparisons with the tow vehicle taken out of the equation. Folks can argue about hitch setups on here until their fingers bleed from typing, but it's all a moot point as long as the nearly infinite combinations of options and tow vehicles are thrown into the mix. It can only be a great addition to the wealth of information archived here. Thanks Andy!
Most of the forum members would have a stroke if I told them I tow my Airstream with nothing but a ball and two safety chains. That is, until you realize the truck weighs twice as much as the trailer, is only a couple of feet shorter than the trailer and still carries considerably more weight on the front axle than the rear while hitched up.

[ROBERTSUNRUS]

Hi, what I would like to see is: How far does a 1,000 lb spring bar have to bend, to have, or hold, 1,000 lbs. And what is the difference in inches, or some other measurement, comparing same rating spring bars from different companies. Also since my set-up has 1,000 lb spring bars, I would assume that, that means each bar is actually 500 lbs.

[PJohnson]

Originally Posted by Journalist

Most of the forum members would have a stroke if I told them I tow my Airstream with nothing but a ball and two safety chains. That is, until you realize the truck weighs twice as much as the trailer, is only a couple of feet shorter than the trailer and still carries considerably more weight on the front axle than the rear while hitched up.

Since you do not use weight distrubution, approximately 50% of the trailer tongue weight will have been removed from the front axle (Weight addded behind the rear axle creates a lever action that removes weight from the front axle.). If you are not carrying enought weight in the bed of your truck to replace the lost weight on the front axle, would you be so kind as to let us know where and when you will be on the highway so that we can take alternative routes.

[barts]

Originally Posted by PJohnson

Since you do not use weight distrubution, approximately 50% of the trailer tongue weight will have been removed from the front axle (Weight addded behind the rear axle creates a lever action that removes weight from the front axle.). If you are not carrying enought weight in the bed of your truck to replace the lost weight on the front axle, would you be so kind as to let us know where and when you will be on the highway so that we can take alternative routes.

Errr... you need to compensate for the difference in distance between
the ball and rear axle, and the distance from the rear to the front axle.

If we call L1 the distance from the ball to the rear axle, and WB the wheelbase (distance between axles), we can tell that:

L1/WB * TW = weight removed from front axle.

since the torque (force * distance) has to balance around the rear
axle.

In many cases, this means that the actual effect of 500 lbs of tongue weight is perhaps 100 lbs less weight on the front wheels - less than the effect of carrying a passenger in the front seat.

- Bart

[barts]

Originally Posted by dznf0g

I suspect that some of the tapered bars MAY BE a progressive rate setup. We'll see, because this is information that the MFRs have kept close to the vest. I suspect the round bars and square bars which do not taper or change shape along their length out to the tip will be linear in their deflection until the force nears the max. rating of the bar.

This cannot be; deflection of a beam made of a material that obeys Hooke's law is always linear with respect to a defined loading condition. Progressive springs as used in vehicle suspensions typically rely on some of the coils compressing 100% in the case of coil springs in motorcycles, or leaf spring leaves that don't engage until the load reaches a certain point (truck overload springs), or linkages that deflect significantly and change their leverage (mono-shock motorcycle suspensions).

Originally Posted by dznf0g

So much is going to be dependent upon the various alloys used in the spring bars also. I think, in previous discussions we all have a tendency to think all materials used by various MFRs are created equally. Not necessarily so.

All steel alloys have very similar modulus of elasticity, which is what determines deflection per unit of stress.

- Bart

[PJohnson]

Originally Posted by barts

Errr... you need to compensate for the difference in distance between
the ball and rear axle, and the distance from the rear to the front axle.

If we call L1 the distance from the ball to the rear axle, and WB the wheelbase (distance between axles), we can tell that:

L1/WB * TW = weight removed from front axle.

since the torque (force * distance) has to balance around the rear
axle.

In many cases, this means that the actual effect of 500 lbs of tongue weight is perhaps 100 lbs less weight on the front wheels - less than the effect of carrying a passenger in the front seat.

- Bart

So, if we assume that the truck has a 140" wheel base and the ball is 48" behind the rear axle: 48/140*500 = 171 lbs. I think this is a bit more than 100 lbs. What happens if I am not carrying a passenger? If I am carrying a passenger, is the passenger weight distributed between the axles or is it somehow just applied to the front axle?

I suppose that I should have said 30 - 50% depending on the vehicle. I was just trying to make the point that weight distribution provides a safety margin by restoring weight to the front axle, wieght that is lost when weight is added behind the rear axle. Weight lost from the front axle means less reliable steering! I have seen to many trailers off the road or jack-knifed because of severe side winds or slipery conditions and in every case (that I have seen) the tow vehicle did not have a weight distribution hitch. Could the accident have been prevented by using weight distribution? I do not know, but, I do know that my rig is set up with the weight properly distributed between the axles. I like my wife, dogs and trailer to much to take a chance.