thomas_malenich
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Re: Weight Distribution (WD) Hitch --- How it Works
Tom, If I saw a topic with this title, I would assume it pertained to why a tow vehicle is limited to carrying a certain amount. However, from your writeup, I assume you are talking about the contribution of tongue weight, hitch head weight, and weight distribution to load on the TV. Rather than going through all the percentage calculations, it might suffice to say that, for estimatimg purposes, one can assume that a properly installed WD system can decrease the vertical load on the receiver by an amount equal to 1/3 of the hitch weight. However, one should always measure the actual weights for comparison with the TV and TT ratings. Thanks Ron, ____________________________________________________________________ I did want to make a point of how much (in percentage) a WD hitch relieves the rear axle, hitch, and payload capacity. I was not going to go through the percentage calculations - just use some of the results. I am still not sure about the weight of the WD hitch itself - would any of the 100#s be noticed in the rear axle load (after engagement)? Would the full 100#s be used to reduce the hitch capacity in my example from 300#s to 200#s removed? I know that a Hensley would be added to the tongue weight, but not sure about an Equal-i-zer or Dual Cam hitch. Seems like they would not become a part of tongue weight, but rather would be primarily supported by the TV hitch.4.7KViews0likes0CommentsRe: Weight Distribution (WD) Hitch --- How it Works
I am thinking of starting a new thread and calling it "Understanding payload and GVWR limits". A part of what I would discuss would incorporate some of what I have learned in this thread. I need everyones help to make sure that I use accurate percentages. I have used Ron's example to figure and extract the rough percentages that I would use. Ron's initial example of: TV wheelbase = 130” TV rear axle to ball coupler = 65” Ball coupler to TT axles = 200” WD spring bar length = 30” WD spring bar rear end load = 1000 lbs/bar = 2000 lbs total I would like to now introduce a tongue weight(TW) of 900#s. Before a WD hitch is engaged: 1. What is the increased load on the rear axle? Approx 1350#s or 150% of TW. The added weight is a combination of tongue weight and front end weight transferred to the rear. 2. What is the decreased load on the front axle? 450#s or 50% of TW. After a WD hitch is engaged as per example above with a total of 2000#s of tension: Summary of axle load changes from Ron : TV front axle 611.54 lbs ADDED TV rear axle 911.54 lbs REMOVED TT axles 300.00 lbs ADDED The WD hitch distributes 300#s or 33% to the TT axles, so the LOAD introduced to the TV is 600#s or 67%. Of this 600#s, 162#s is now on the front axle and 438#s remains on the rear axle. The front axle lost 450#s originally but now it is only increased by 162#s. The load on the receiver has been reduced by 300#s. The load on the rear axle was increased by 150% of TW before the WD hitch was engaged. Now the load on the rear axle is only about 50% of the TW. Conclusion regarding payload: The TV needs 600#s of available payload (not 900#s), after it is loaded with passengers, gear, and fuel. On edit: I did not consider the weight of the hitch itself. Lets say the weight of the WD hitch is 100#s.4.7KViews0likes0CommentsRe: Weight Distribution (WD) Hitch --- How it Works
Tim, You are right. Most sources have published 10% to 15%. Sherline recommends 12% to 15% - not sure if that is the same source that you were thinking of. That said, most of the research that I have done suggests that it is better to be closer to 15% than to 10%. And I support that based on personal experience. Having a range that starts at 10% suggests that 10% is OK, but I think having that asks for a bit of trouble. I have been recommending 13% to 15%, but I would also agree with the 12% to 15% range.572Views0likes0CommentsRe: Weight Distribution (WD) Hitch --- How it Works
Without a WD system, the TV's rear axle load could increase by as much as 150% of the TT's tongue weight depending on overhang and wheelbase. The front axle load could be decreased by as much as 50% of tongue weight. For most TV/TT combos, these axle load changes will make the TV unlevel. The decreased load on the front axle can cause a loss of steering control and braking difficulties. The increased rear axle load might exceed that axle's rating, and the load on the receiver might exceed its rating. A weight distribution system enables a tow vehicle to more effectively handle the tongue weight of a trailer by removing some of the load from the tow vehicle's rear axle and distributing it to the tow vehicle's front axle and the trailer's axle(s). Note - When the WD system is engaged the actual tongue weight does not change. _____________________________________________________________________ Critique of the above statement: I would say the first two sentences are confusing. I understand what you are saying, but the percentages will be confusing to someone who knows little about WD hitches. I would be thinking to myself "How could my rear axle load increase by more than the tongue weight I am adding to it??" I also think the percentages are unnecessary. I think it needs to be simplified. We are not writing this statement for ourselves but for the new members benefit. I still like the second paragraph if you want to go back to that definition of what a WD system does. However I would simplify your first paragraph to read like this: Without a WD system, the tow vehicle's rear axle load could significantly increase from the added tongue weight. Conversely the front axle load will be decreased. These axle load changes will make most tow vehicles unlevel. The decreased load on the front axle can cause a loss of steering control and braking difficulties. The increased rear axle load might exceed that axle's rating, and the load on the receiver might exceed its rating. I would consider adding the recommended tongue weight percentage range to the end of the second paragraph. Those percentages are very important. So the whole thing would look like this: Without a WD system, the tow vehicle's rear axle load could significantly increase from the added tongue weight. Conversely the front axle load will be decreased. These axle load changes will make most tow vehicles unlevel. The decreased load on the front axle can cause a loss of steering control and braking difficulties. The increased rear axle load might exceed that axle's rating, and the load on the receiver might exceed its rating. A weight distribution system enables a tow vehicle to more effectively handle the tongue weight of a trailer by removing some of the load from the tow vehicle's rear axle and distributing it to the tow vehicle's front axle and the trailer's axle(s). Note - When the WD system is engaged the actual tongue weight does not change. Recommended tongue weight is from 13% to 15%.572Views0likes0CommentsRe: Weight Distribution (WD) Hitch --- How it Works
WD hitch forces are not involved directly in TT sway dynamics because they are vertical forces. However, changes in TV axle loads can have a significant effect on TV/TT sway dynamics primarily due to changes in steering response. The vertical load on the tires determines how much horizontal force the tires can generate. ___________________________________________________________________ We can conclude that the WD hitch can be "indirectly" involved in TT sway dynamics, since the WD hitch is responsible for changes in TV axle loads.572Views0likes0CommentsRe: Weight Distribution (WD) Hitch --- How it Works
Such confusion about loads resulting from mass versus loads resulting from other effects is the reason I am trying to avoid the use of the term "weight distribution" and its counterparts. ____________________________________________________________________ Ron, I hear you. We all went through that a while back. I once suggested that we should consider not using the term "tongue weight" once the tongue is hooked to a TV and no longer supported by the tongue jack. Unfortunately the manufacturers use words such as "weight distribution", and "distributes tongue weight", and "the rear axle bears much of the tongue weight". We can not fight them. I feel that we can provide the best service to the new members using the ORF search, by providing a definition/summary consistent with the manufacturers, yet enlightening. That is why I wrote my summary using a blend of manufacturers wording and our/my wording.573Views0likes0CommentsRe: Weight Distribution (WD) Hitch --- How it Works
Ron, I would like to take this opportunity to thank you for this thread. Your work, insight, and knowledge are greatly appreciated. I have thoroughly enjoyed the debates and light-hearted jabs. I have learned alot from you and as much from the other members who participated in this thread. I know that I flipped and flopped, but I was only trying to argue my points at a given time and my perspective changed vastly throughout. I re-read the entire thread yesterday and it was like watching a good movie a second time. You know - you always miss something the first time. Thanks again Ron, and a special thanks to Barney for tolerating us and allowing the thread to run its course. Tom393Views0likes0Comments
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