Tongue Weight Rating

Ron Gratz wrote:

LarryJM wrote:
I look at this a a fairly straight comparison with the tongue wt. being the weight of the bikes and the WDH system and bars being the same as the bike rack.

I don't see any comparison at all. A bike rack is not a weigh distribution hitch. It does not have the ability to remove load from a receiver the way a WDH does. This thread is about tongue weight rating when using a WDH.

I have also read that once you get things hooked up any wt. you add to the TV behind the axle should be considered as "additional" tongue wt.

I've read a lot of stuff on the internet which I consider to be nonsense. If weight behind the rear axle is considered to be "tongue weight", does that mean it also must be subtracted from the receiver's tongue weight rating? I think not.

I guess the way I look at it is that the receiver is designed to support a certain dead wt in direct load bearing or WDH bearing which is the actual load on the receiver.---

The actual vertical load on the receiver is weight of WDH plus tongue weight minus load transferred to TT's axles. In most cases the load transferred to the TT is greater than the weight of the WDH. That means the actual vertical load on the receiver would be less than the tongue weight.

---You could hook up your WDH system and not engage the WDH portion and I guess the question is do you ignore the 100lbs approx of the WDH and bars against the receiver weight carrying capacity and if so why or where does it go.

If you use a WDH as a "weight carrying" hitch, the question is -- how much weight of hitch already is included in the "weight carrying" tongue weight rating?
I'm guessing that the people who establish receiver ratings are aware that, when used in WC mode or WD mode, there will be a WC or WD hitch installed in the receiver. And, I'm guessing that the weight of a typical WC or WD hitch already is included in the receiver's rating.

Ron

Ron, I read through this post (http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/14265335.cfm) and I can’t say I understand the physics or where the formulas come from, but I get the gist of how the WD hitch distribute weight between the TT and TV axles. What I didn’t realize (fully) is, when installed, WD hitches do not change tongue weight. This was mentioned a couple times throughout this thread and it took a bit for that to sink in. I’m still not sure I understand why that is, but I can accept it.

The reason I didn’t catch on to that at first (and this goes to the OP’s original question) is on my old truck (1/2 ton Silverado) the sticker on the receiver read something like 600 lb. TW and 1,200 TW with a WD hitch. (The class V hitch on my new TV doesn’t say that—it just says 1,500 lb. TW) So somehow (through the magic of physics) adding a WD hitch increases the amount of tongue weight you can apply to the receiver.

So my question is, if a given hitch is rated for a tongue weight of (for instance) 600 lbs. and WD hitches do not change tongue weight, how does adding a WD hitch increase the allowable TW to (for instance) 1,200 lbs.? I’m sure there’s something I’m not seeing here.

Ron,

All I can say is in my basic premise that one could reasonably consider having all the WDH including the drawbar attached to the trailer tongue and similar to a HA insert that into the receiver and in my view all that wt. would be then considered "TRAILER TONGUE" and "RECEIVER TONGUE" weight. The end effect is the same ... it's temporary wt. in the leverage area of the tow vehicle that is and will be redistributed by the WDH just like the "dead tongue wt. of the trailer itself". I see do difference in the two wts. with respect to the WDH system used. Sort of like this cargo behind the axles. Any non fixed temporary weight that is added behind the rear axle on a TV is subject to being redistributed by the WDH system when used and really no different than the "temporary" tongue wt. from just the trailer. One caveat is that this cargo wt. doesn't translate one to one to additional "TONGUE WT" since that is a function of the distance of the wt. from the rear axle of the TV and the it's distance from the ball or more accurately the fixed end of the WDH bars on the hitch head which are basically at the position of the ball. Your point about bringing the vehicle back or close to the same heights IMO still has to account for the weight of the WDH and the cargo behind the axle and in general those two won't change the measurable heights like the much higher tongue wt. from the actual trailer, but are still weights that have the same class of leverage as the trailer tongue wt. on the vehicle at the receiver. The one, two, three hundred pounds that we are talking about in general and insignificant by them selves, but are still there and will be acted on and redistributed by the WDH just as the much heigher "TRAILER TONGUE WT" will.

All I can say is you asked for some outside information and that is what I provided and I guess you can disagree, but I put the same challenge to you and for you to provide some verifiable independent information from you source to counter what e-trailer has provided. I'm not saying you are wrong, but I don't feel you have proven what e-trailer is saying wrong or incorrect either.

BTW I'm not going to look for it, but I remember seeing similar opinions on this cargo topic behind the axle from other sources, but have never seen a source saying cargo added behind the axle has no effect on the tongue wt. seen by the receiver and can be ignored.

Larry

myredracer wrote:
etrailer's explanation in that link is wrong, and on more than one point.

Well I tried to provide some outside independent information which no one else including you have done to counter what I provided. You have a right to say whatever you want, just I have a right to consider it with the proper weight which based on just your post and the lack of information as basically zero weight.

Larry

I read every one of the postings and didn't understand most of it. But need help. We have been without a rig of any kind for about a year - and hating it. Previously owned pop-up, travel trailer, motorhomes. We're going back to a travel trailer and having to purchase a TV and TT. I want a Ford Expedition, can't buy a 2014 unless we win the lottery. Probably going to buy a 2010-2012. I'm sure it's going to have a standard tow package and not the heavy duty tow package. We liked the TT we owned previously - R-Vision Trail Sport 27QBSS. We would like to be able to pull with the Expedition (hopefully EL). Need to be able to determine if we can do that (we previously pulled with 2001 Dodge Ram Pickup, 2500). What do we need to do to be sure we purchase the right vehicle for the job?

I have looked at specs for Expedition, took the low weight of 6000 tow weight. Subtracted 1000 lbs for cargo on trailer; also subtracted 1000 lbs for people and other TV load. So, that means a trailer 4000 lbs or lighter. I have no idea what else I need in order to pull the trailer (hubby is an accountant, I'm an engineer...surely we an figure this out).

Do we need to purchase an add-on tow package? I don't understand the weight distribution hitch. All I remember about towing is the sway bar.

Help!

etrailer's explanation in that link is wrong, and on more than one point.

lbrjet wrote:
This is my point. The hitch weight needs to be added to the TW against the receiver rating. I have never seen any literature saying that weight removed by the WDH should be subtracted from what should be applied against the receiver rating: hitch weight + tongue weight.

I've never seen any literature saying that load can be added to a receiver, but cannot be subtracted from a receiver.

You are considering only the loads which are added by tongue weight and WDH weight.
I am considering those loads and the load which is removed from the receiver via application of WD.

Application of WD does not reduce the tongue weight but, as far as vertical load on the receiver is concerned, it has the same effect as reducing the tongue weight.
If you want to say that "tongue weight" (as opposed to actual tongue weight) is equal to actual tongue weight plus the weight of the WDH minus load transferred to the TT, that's a matter of definition.
However, your "tongue weight", for any practical application of WD, still is going to be less than the actual tongue weight.

Ron

LarryJM wrote:
Well as far as cargo behind the axle the "experts" at e-trailer seem to have a different opinion ....
tongue wt. added to receiver rating

Larry, the "expert" failed to explain that allowing for weight of cargo behind rear axle only is necessary if you are going to use the WDH to compensate for the effect of that weight on the TV. Others, who also might be considered to be experts, disagree with this approach.

The majority of TV and WDH manufacturers agree that, if a WDH is used, it should be adjusted to restore the front of the TV to its unhitched height or somewhere above the unhitched height.
I've never seen anyone specify that the unhitched height should be measured with no cargo behind the rear axle, and you then should add that cargo to the TV and connect the trailer.
Since the behind-the-axle cargo already is in the TV when the unhitched height (or load) is measured, the WDH does not compensate for the weight of that cargo.

Even if one did go to the trouble of unloading the behind-the-axle cargo prior to measuring the reference height or load and then reloading that cargo, the effect of that cargo on the TV only would not be the same as an equal amount of tongue weight.

Again I was careful to keep my comments about the receiver ratings as they are listed as tongue wt. I can't do the analysis you can, but I can appreciate that cargo wt. behind the axle is part of the wt. that the WDH leverages and transfers since the pivot point is basically the rear axle so any wt. behind that might have to be handled by the WDH system. Thus I would count the WDH wt. as cargo basically added behind the rear axle.

IMO, the WDH should be in the receiver and the bars (along with all of the TV's cargo) should be on/in the TV when the unhitched heights or loads are measured. If you choose not to do that, then a portion of any weight which is added to the TV after the reference measurements are made can be considered to be redistributed by the WDH.
However, we should consider that receiver tongue weight ratings probably are based on the assumption that the WDH will be adjusted to give "equal squat". Since that approach seldom is used these days, the actual loading of a receiver by a WDH probably is significantly less than the receiver's design assumptions.

While you don't consider the bike rack like the WDH wt., but again neither do the TW ratings of the receiver spell out that the wt. of the WDH is tongue wt in a weight carrying mode (i.e. the draw bar and even the spring bars if not engaged), but are a free wt. when the WDH is engages.---

Sorry, you lost me there.

---Also, do you advocate subtracting the parts of the WDH like the spring bar brackets that generally stay on the tongue from the actual tongue wt. somehow?.---

I would consider the weight of the spring bar brackets to be part of the weight of a typical WDH which probably is allowed for when the receiver's TW rating is established.

I guess then you stance/opinion is that the wt. of the HA is a freebe on any considerations as far as weight goes which I don't think is a universally help view from my reading.

IMO, the weight of the HA (or any other WDH) should be treated as part of the TV's GVW. If you are going to use the WDH to achieve "equal squat", I would recommend that you consider the weight of the HA, minus 100#, to be added to the trailer's tongue weight.

BTW e-trailer also considers wt. behind the rear axle as going against "tongue wt" CLICKY even in a WDH scenario and I think it's reasonable to consider the WDH wt. as basically cargo or wt. behind the rear axle.

Is this information different from that presented in your first CLICKY?

Ron

Ron,

You said "My logic says that, if you start with zero load on a receiver and insert a 100# WDH, you end up with 100# on the receiver."

This is my point. The hitch weight needs to be added to the TW against the receiver rating. I have never seen any literature saying that weight removed by the WDH should be subtracted from what should be applied against the receiver rating: hitch weight + tongue weight.

Ron Gratz wrote:

lbrjet wrote:
No Ron I have no link, just logic since the hitch and bars are literally hanging on the receiver it makes sense to me that they should be included against the receiver rating. This would be no different than adding a third propane tank and claiming it didn't increase the tongue weight.

Adding a third propane tank would increase the tongue weight.

Attaching a WDH to a receiver does not increase the tongue weight --
but it does increase the vertical load on the receiver.

Applying load to the WD bars reduces the vertical load imposed by the TT on the receiver.

Tongue weight is tongue weight. It doesn't change unless you change the weight of the cargo or relocate the cargo.

My logic says that, if you start with zero load on a receiver and insert a 100# WDH, you end up with 100# on the receiver.
If you then place the coupler of a 1000# tongue weight trailer on the ball, you now have 1100# on the receiver.
If you then adjust the WDH to transfer 200# of load from the receiver to the TT's axles, you now have 900# on the receiver.

The net vertical load on the receiver ends up being 100# less than the tongue weight.
The receiver really doesn't care where the loads come from, it only cares what the net load is.

The stress imposed on a receiver is largely due to the pitch-axis torque generated by the WD bars -- on the order of 4000 lb-ft for a 1000# TW.
An opposing torque of about 1000 lb-ft is generated by the downward load imposed on the hitch head. This opposing torque reduces the torsional stress in the receiver.
The weight of a 100# WDH generates additional opposing torque of about 100 lb-ft -- further reducing the torsional stress by a small amount.

Ron

Well as far as cargo behind the axle the "experts" at e-trailer seem to have a different opinion ....

tongue wt. added to receiver rating

Again I was careful to keep my comments about the receiver ratings as they are listed as tongue wt. I can't do the analysis you can, but I can appreciate that cargo wt. behind the axle is part of the wt. that the WDH leverages and transfers since the pivot point is basically the rear axle so any wt. behind that might have to be handled by the WDH system. Thus I would count the WDH wt. as cargo basically added behind the rear axle.

While you don't consider the bike rack like the WDH wt., but again neither do the TW ratings of the receiver spell out that the wt. of the WDH is tongue wt in a weight carrying mode (i.e. the draw bar and even the spring bars if not engaged), but are a free wt. when the WDH is engages. Also, do you advocate subtracting the parts of the WDH like the spring bar brackets that generally stay on the tongue from the actual tongue wt. somehow?. I admit it's sort of fuzzy, but I'm still in the camp and of the opinion that the WDH does and should count against the "RECEIVER tongue wt." rating.

I guess then you stance/opinion is that the wt. of the HA is a freebe on any considerations as far as weight goes which I don't think is a universally help view from my reading.

BTW e-trailer also considers wt. behind the rear axle as going against "tongue wt" CLICKY even in a WDH scenario and I think it's reasonable to consider the WDH wt. as basically cargo or wt. behind the rear axle.



Larry

One way to conceptualize this is when you separate the tow vehicle from the trailer, all that is left on the trailer is the snap-up brackets (or eqivalent) and the weight of them is all that remains with the trailer. The weight of the hitch shank and spring bars remains with the TV. This is why when you go to a scale, you should put the spring bars in the back of the TV when you make the pass with them disconnected. If spring bars always remained as a fixed part of the trailer tongue, it'd be different.

The measured tongue weight does not change unless you change the loading of the trailer. If it measures 1,000 lbs, it's always 1,000 lbs to the trailer. But the WDH moves this weight between the 3 sets of axles through leverage action and the TV itself sees a somewhat reduced weight - maybe 200 lbs or so less and the TV will "see" 800 lbs.

The best explanation of this on the entire internet is this: Ron Gratz on WDH hitches It's a very good read, especially for mathematical types. Otherwise, just take his word for it. :)