RE: WDH sticky diagram is missing - geocities closed
Bryan and Barney,
Thanks for letting me know about the missing link.
I've located a backup copy of the WD diagram image file and, with Barney's help, we'll see if we can get a new link placed in the closed thread.
Ron
RE: A lesson in Torque
Horsepower, by its very definition, defines how fast you move how much weight. Period. That is actually the basic definition of horsepower. No way around that, without redefining some pretty major, basic definitions that have been around a looooooong time.
Will, help me to understand the physics here.
Let's assume a TV/TT combination weighs 15,000 lbs and it is propelled along a level highway at 60 mph (88 ft/sec). If we multiply the weight times the speed, we get 15,000*88 = 1,320,000 lb-ft/sec.
By definition, one horsepower is equal to 550 lb-ft/sec. Does this mean moving the 15,000 lb TV/TT at 60 mph requires 2400 hp?
Ron
RE: Newbie question about towing with Ford Explorer
Wheelbase is ACCOUNTED for when the set the tow ratings for EVERY TOW VEHICLE on the market. Longer wheel base vehicles have higher tow ratings.---
If you look at the GM Online Order / Reference Guide, you'll find that just the opposite is true for GM trucks.
For the Silverado 1500 with 5.3L V8 and 3.73 rear end:
Model Wheelbase MaxTowCapacity
CC10703 119.0" 8200#
CC10903 133.0" 8000#
CC10753 143.5" 7700#
CC10953 157.5" 7600#
Longer wheelbase does not give you a higher tow capacity. Given the same engine and rear end ratio, longer wheelbase results in a lower tow capacity -- probably because the longer wheelbase means the truck is heavier.
If you want a higher tow rating, you need to increase the horsepower and/or rear end ratio.
Ron
RE: Husky TT Hitch with sway control and wt distribution
As far as I know, Husky does not make a "duel cam" sway control which is the same as the Reese Dual Cam sway control.
However, Husky does sell the Center Line Sway Control (click on "Centerline Brochure").
Ron
RE: This doesn't look right.
Perhaps you are focusing too much on the rear end squat.
A better way of determining when the WD system is properly adjusted is to measure the front wheelwell height "before" (loaded TV only - no TT attached) and "after" (loaded TV plus loaded TT with WD adjusted). Better yet -- measure the load on the front axle before and after.
When the front of the TV is returned to the "before" height or weight, then you have the correct amount of weight distribution. The TV does not need to be level.
Ron
RE: Wind while towing
Missing the point IMO, everyone jumped the TV to TT length and skewed the post as it was the only calculation of any importance.Not everyone was claiming that TV wheelbase and TT length was the only calculation of importance. The OP asked about TT weight. The wheelbase/length debate began with this statement in the fifth post:
Wheelbase ratio to trailer length first critical decision. Look online for this ratio but in a simplified form "if your TV has a wheel base of 110" you can tow a 20' trailer and you can safely tow one additional foot for every 4" of wheelbase".
The point is -- "wheelbase ratio to trailer length" is not the first critical decision. The first critical decision should be selecting a TT which is within the TV's towing weight limits.
We can argue forever about origin, old school, but totally ignoring this ratio is a big mistake. New construction of todays TT are making them longer and lighter, which allows smaller and lighter TV to keep within their GVW while allowing the TV to TT length ratio to rapidly increase. Alarming actually, even with new technologies in the hitch, aerodynamics, suspension, and other aspects of the TT design, bad decisions could easily be made which impact the safety if the TT length is totally ignored as suggested.I don't think anyone is suggesting TT length should be totally ignored. People are just questioning the validity of the "old formula". There are many people who exceed the formula by 5-7' or more and appear to be doing it safely.
The bottom line, using the existing formula is a very good starting point (until a new one is calculated), then factor in, new technology hitches, paying attention to TV sizes, matching the TT to TV aerodynamics, and a good deal of common sense, a safe towing environment is sure to be the out come.IMO, the proper starting point, which seems to be missing from your list, is making sure the TT weight is within the TV's ratings. Unfortunately, when people cite the wheelbase/length formula, they usually don't mention the other factors which should be considered.
Ron
RE: Wind while towing
Those old formula are still valid.
Nobody seems to know how or by whom the old "formula" was derived; so it's pretty hard to know if it was ever valid. Perhaps it has some merit if you want to tow a 1950s/60s TT with a 1950s/60s sedan.
The physics of towing travel trailers has not changed.
I agree. Physics has not changed. However, tow vehicles and travel trailers have changed.
The formula says that a 130" WB 3/4 ton Suburban cannot safely tow a TT longer than 25'. And, we must assume the 25' is ball-to-bumper since the formula does not state otherwise.
I doubt the formula was based on physics. More likely, it was based on loosely-applied statistics for TV/TT combinations of the day. Physics says TT weight should matter; the formula says it does not. Physics says TV weight should matter; the formula says it does not. Physics says TV rear overhang should matter; the formula says it does not.
There are better ways of determining how much a TV can tow.
Ron
RE: Wind while towing
---Regarding sway stability, here are is my prioritized list that is backed up by a theoretical understanding and some instrumented testing:
1. Yaw inertia of the trailer - lower is better (see http://www.towingstabilitystudies.co.uk/measuring_stability.htm) for more information. This is very important, but hard to measure. In my pop up, the cargo weight is a much more significant part of the total weight and when I loaded for low yaw inertia, the sway was much better. I have also done experiments where the tongue load is always 10%, but we varied the yaw inertia and it had a huge effect on the sway stability.
2. Longer axle to ball distance, this tends get longer with longer trailers, so it is rarely something that distinguishes TT's from each other. However boat trailers tend to have this distance be longer than TT's and also have lower tongue weights and you generally see much fewer anti-sway devices on boat trailers.
3. Tongue weight - more is better
4. Trailer tires (cornering stiffness which is influenced by inflation pressure and tire type)
5. Tow vehicle rear overhang to wheelbase ratio (less overhang is better, longer wheelbase is better, consider shortening your ball mount)
6. Tow vehicle wheelbase - longer is better
7. Tow vehicle cornering stiffness - higher is better (this is a function of the tires and suspension. Also heavier vehicles tend to have higher cornering stiffness)I note that neither TV weight nor TV yaw inertia is included in your list. Do you think they should be? If so, where would you rank them? The University of Bath towing studies which you referenced are a good source of towing "sensitivity" information. For example: THE DYNAMICS OF TOWED VEHICLES.
I have never used or tested a Hensley (or ProPride), but I can see that it does 2 things:
1. It makes the trailer better behaved because the pivot point is further away from the trailer axle(s) which reduces the tendency for the trailer to sway.
2. It makes the tow vehicle much stiffer laterally since the lateral loads go in something like 55 inches forward of the hitch, so the overhang is around zero.The virtual pivot point is projected about 54" forward from the ball coupler. For many TVs, this places the VPP about 24" behind the center of the rear axle.
Ron
RE: Wind while towing
If folks paid more attention to balance, aerodynamics, suspension, centre of gravity, brake controller quality/setup, and hitches they wouldn't have to be so concerned about weight and length.
Some of the best handling combinations that have ever graced this earth have....
A. A tow vehicle that weighs 1/2 as much as the trailer and
B. A 30' plus trailer that is being towed by a TV that has a wheel base less than 120"
Perhaps we could limit this discussion to the more "conventional" TV/TT combinations -- i.e. the vast majority which are not an Airstream trailer towed by a Dodge Intrepid (or something similar). Also, it would help to limit the discussion to yaw stability which was the basis for my initial comments.
Balance - what balance are you referring to and why do you feel that balance is much more important than the weight of TV and TT as regards yaw stability?
Aerodynamics - TV and TT aerodynamic characteristics primarily affect towing power requirements. Lateral aerodynamic forces acting on the TT are primarily resisted by TT weight and yaw inertia (which is dependent on TT weight). How can aerodynamics be much more important than weight?
Suspension - the suspension characteristics help to determine lateral stability, yaw stability, and roll stability. So does TV weight. How can suspension be much more important than weight?
Centre of Gravity - given the typical variations in location and height of TV and TT COGs, how much influence do you believe COG has on yaw stability and how much influence do you believe TV and TT weight have on yaw stability?
Brake Controller - how does quality/setup enter into yaw stability and why is it much more important than TV and TT weight?
Hitches - In your opinion, are there hitches which will allow a user to safely disregard TV/TT weight relationships?
Ron
RE: Sway
So back to our OP's question;
can a premium WD and sway system eliminate sway from happening assuming the TV is more then capable and set up properly?
Here we go, and I'll say it again for all the peanut gallery who have never owned one and yet comment more than most.......everyone listening......???????
YES (in my experience)
Once again, we are 6 pages into a discussion of "sway control" without having defined "sway". In addition to the above question, the OP also stated,
"I know sway can still happen with a 5er but you do not seem to hear about it as much if all is set up properly."
This begs the question -- If "sway" can happen with a 5er, how is it that "sway" cannot happen with a TT being towed by a "premium" hitch?
I think BurbMan gave the best assessment regarding "control" versus "eliminate":
"The Hensley, ProPride and PullRite are 3 hitches that do not rely on friction to control sway, they use geometry to "project" the pivot point between trailer and tow vehicle to a point close to the rear axle. See the sticky at the top of the forum about "Hensley Arrow: How it Really Works". Whether they can control sway 100% of the time is academic, but their designs are far superior to friction-based sway control, and at a minimum they offer a level of sway prevention that is waaaaay beyond anything else on the market."
There is an important safety concern which has been overlooked in this thread -- the "bump". Every hitch which must rely on a 4-bar linkage for sway control has an undesirable, and potentially unsafe, feature. This feature, which is fondly known as the "bump", can arise when the TT is allowed to push forward against the linkage. The "bump" can result from TT brakes which malfunction or are not properly adjusted, and it can result from a brake controller which malfunctions or is not properly adjusted.
A 5er does not have the "bump"; and, IMO, a 5er is inherently more safe than a TT connected to a 4-bar hitch. A PullRite does not have the "bump"; and, IMO, a PullRite is inherently more safe than a TT connected to 4-bar hitch.
If I were ranking TT hitches as "good", "better", and "best", I would put the PullRite alone in the "best" category.
Ron
(one of the "peanut gallery who have never owned one" -- but, I do know of a couple ORF members who have owned both a 4-bar hitch and a PullRite; and I think they might agree with me)
RE: 2 way vs 3 way refrigerator
We have an 8 cu ft Norcold with the 3-way feature. The unit cools equally well in all modes.
With the DC operation, you can have the propane shut off while travelling and still run the refrigerator.
Ron
RE: Wind while towing
Also include about another 45 factors. When optimally connected weight and a long wheelbase can be way down on the list.
I assume by, "way down the list", you are implying that weight and wheelbase are much less important than other factors.
Can you please list some factors which you consider to be much more important than TV and TT weight and explain why?
Ron
RE: Wind while towing
---Where did this formula come from.....honestly? It's been kicked around on the internet for years as if it's gospel.
My thoughts on the subject can be found here. The following is an excerpt from that post:
IMO, we have no clear understanding as to how TT length affects TV/TT yaw stability. However, IMO, it is pretty clear that there are four primary factors which do affect stability. These are:
Tow Vehicle Weight
Tow Vehicle Wheelbase
Hitch Overhang (distance from TV rear axle to ball coupler)
TT Weight
The "guideline" attributed to RV.ORG ignores three of these four factors. My guess is that the "data" which were used to formulate the "guideline" might have contained some correleation between TV weight (which might be correlated to TV wheelbase) and TT weight (which might be correlated to TT length).
One could then take an "average" wheelbase for a range of TV weights and take an "average" length for a range of TT weights and come up with a wheelbase-length relationship for "safe" and "unsafe" TV/TT combinations. However, correlations that might have been appropriate for TV/TT combinations which existed in the 1950/60s (or whenever the unknown data were collected) might not be appropriate for combinations in use today.
Bluwtr49 suggested that the "guideline" is ultra-conservative. I agree. IMO, staying within all the TV manufacturer's weight ratings is the primary consideration. If you do that, then the TT length probably will be acceptable also.
Ron
RE: Weighing in.
The 40# difference most likely is due to scales' error. Cat scales readings, for example, are said to be accurate to within 80#.
Scales usually read out in 20# increments. If the non-WD reading were off 20# in one direction and the WD reading were off 20# in the other direction, the difference would be off by 40#.
Ron
RE: Sway
So I guess my question is, can a premium WD and sway system eliminate sway from happening assuming the TV is more then capable and set up properly?
It depends on how you define "sway".
I know sway can still happen with a 5er but you do not seem to hear about it as much if all is set up properly.
Given that sway can happen with a 5er, then one must conculde that a premium sway control cannot eliminate TT sway since the primary purpose of a premium sway control is to emulate the action of a 5er connection.
Ron
RE: Weighing in.
Jim, you seem to be in good shape. Your TT and TV were loaded as if you were going for a real trip. The TV GVW with WD applied is 8740# which is below the 9000# GVWR. And the GAWs are well below the axle ratings.
You might want to consider increasing the load on the WD bars. With the WD applied, you transferred only 100# to the TT axles. With your 900# tongue weight and 1000# WD bars, you should be able to transfer at least 200#.
If you transfer an additional 100# to the TT axles, that will cause about an additonal 200# to be added to the TV's front axle and will cause about an additional 300# to be removed from the rear axle.
Then the front axle load would be about 4480# versus 4420# for TV only and the rear axle load would be about 4160# versus 3560# for TV only. And, if you increase the load on the WD bars, your Equal-i-zer will provide better sway control.
Ron
RE: Weighing TV and TT
1. Pull front tv axle onto scale for front GAW.
2. Pull just tv onto scale for GVW.
3. Pull tv & tt onto scale for combined GCW.
4. Pull tv front axle off scale for rear axle GAW.
5. Pull tv off scale for tt weight.
6. Pull front tt axle off scale and subtract weight from 5 above for front tt axle weight - difference would be rear tt axle weight.
7. Disconnect tt and weigh tv separately for GVW and subtract this weight from 3 above for tt GVW.
Step 5 will give the TT (hitched) GAW. The TT axle weight is not the same as the TT GVW. Step 7 will give the TT (unhitched) GVW.
I think you can omit step 4. The rear axle GAW should be equal (within the accuracy of the scales) to the TV GVW (2) minus the front GAW (1).
Your multiple weighings should give the desired results as long as the approach to the scales and the departure from the scales are level with the scales platform.
Ron
RE: Weight Good To Go?
NO matter how high or low the rear shocks get, either way I would connect the WD, the Auto Leveling will set the rear wheel well to about 36" when it's all said and done. These are auto leveling air shocks. There is a compressor with a sensor that will raise the rear end if it is below 36" and will let air out if it is above 36" for a period of time. Therefore I don't really see the need to have the fuse in when I am adjusting the WD. My brain is spinning so what the heck do I know anyway. Ha Ha
My previous "scenario" was based on the apparently incorrect assumption that your Suburban has the "self-adjusting rear suspension" which employs a hydraulic pump inside each rear shock.
Based on your description, it appears you actually have the "automatic level control rear suspension" (Automatic Level Control) which adjusts the height at the rear axle only. This system does not require that the TV be driven a couple miles to activate the "leveling". This system would result in a different scenario if the manufacturer's recommemded procedure is followed:
1) With the TT unhitched, the TV sits "level" and at the original ride height.
2) The TT is attached without WD being applied. Load on the rear axle increases and the rear of the TV drops below original height. Load on the front axle decreases and the front rises above original.
3) The ignition is turned to the RUN position and the air shocks raise the rear back to the original height. The front of the TV remains above original height.
4) The WD system is then adjusted to return the front to its original height. During this process the ALC will keep the rear of the TV at the original height. If the front of the TV is above the original height, you need to increase the load on the WD bars (have fewer links under tension). If the front is below original height, you need to decrease the load on the bars. When the front is at the original height, the TV will be "level"
If you do not have the fuse in when adjusting the WD system, I think the following would happen:
1) With the TT unhitched, the TV sits "level" and at the original ride height.
2) The ALC is disabled.
3) The TT is attached without WD being applied. Load on the rear axle increases and the rear of the TV drops below original height. Load on the front axle decreases and the front rises above original.
4) The WD system is then adjusted to return the front to its original height. The rear of the TV will rise, but will remain below the original height. The TV will not be "level".
5) If the ALC is subsequently enabled, it will raise the rear of the TV back to the original height. This will cause the load on the WD bars to be reduced. That, in turn, will decrease the amount of load transfer to the front axle. You will end up with too much load on the rear and too little on the front.
Ron
RE: Weight Good To Go?
-he only honest safe way to setup a WD hitch is WITHOUT the aid of ANY suspension aids, helpers, air shocks...etc. interfering. Once the proper adjustments have been made and the rig is correctly setup, then what ever small amounts of further suspension adjustment are needed can be handled by the leveling system down the road, without interfering with the optimum setup of your WD hitch,
I don't think so.
If you turn off the leveling system and apply WD to bring the front end of the TV back down to the original height (as recommended by the TV manufacturer), you will end up with about 75% of the tongue weight on the rear axle. Let's assume this value is 750#. This load, plus whatever gear is in the rear of the TV, will cause the rear end to drop.
If you then turn the Load Control back on and head down the road, the Load Control will raise the rear of the TV to make it level with the front. Raising the rear will decrease the load on the WD bars. This will cause the front of the TV to rise and the rear to drop.
Now the Load Control will raise the rear of the TV to the make it level with the too-high front. Raising the rear, relative to the front, will further reduce the load on the WD bars, causing the front to rise even more.
It looks to me as though this might be a diverging process which will reach its limit when the front of the TV gets as high as it can go and/or the rear shocks are at maximum "lift". If the process does converge, you will end up with both the front and rear of the TV higher than the original height -- not a good thing.
At least, that's how I see it.
Ron
RE: Weight Good To Go?
Additionally, in order to comply with those instructions, you would likely have to exceed the Weight Carrying tongue weight limit on your receiver for a period of time, on public roads and with traffic around you. Under the right circumstances, it would be possible to damage or fatigue your GM hitch---.
I think it very unlikely there would be damage or fatigue. I'm guessing the receiver design is controlled by the pitch-axis torque imposed by the tongue weight and the WD system. A 1000# tongue weight acting about 12" behind the receiver's cross tube would impose a torque of about 1000 lb-ft in the WC mode. In the WD mode, the torque would be increased to about 4000 lb-ft.
Ron
