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RE: Back from the scales
---Ron, curious how you arrived at the TW.---
The net load removed from the front axle is a function of three TV/TT dimensions and two unknowns: 1) the tongue weight, and 2) the load transferred to the TT axles by the WDH.
The net load added to the rear axle is a different function of the same TV/TT dimensions and the two unknowns.
This means we have two simultaneous equations from which the two unknowns can be calculated when we know/assume three TV/TT dimensions and the net load changes for the front and rear axles.
The solution for tongue weight is as follows --
Let: a = TV wheelbase, b = TV ball overhang, c = distance from ball to midpoint between TT axes.
Let: C5 = (b+c)/a, C6 = (a+b+c)/a, C7 = b/a, C8 = net load added to TV's rear axle, and C9 = net load removed from front axle.
I then assumed: a = 130", b = 65", and c = 255".
The measured values for C8 and C9 were 1200# and 200# respectively.
The equation for tongue weight is --
TW = (C8*C5 - C9*C6)/((1+C7)*C5 - C6*C7).
For the assumed and measured values,
TW = (1200*2.46 - 200*3.46)/(1.5*2.46 - 3.46*0.5) = 2260/1.96 = 1153# rounded to 1150#.
The load transferred to the TT axles then is equal to the tongue weight minus the load carried by the TV or,
load transferred to TT = 1150# - 1000# = 150#.
Ron
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Ron Gratz
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05/25/13 07:50pm |
Travel Trailers
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RE: Back from the scales
Travel trailers need 3 passes. Truck alone, truck and trailer with WDH on, and truck and trailer with WDH off (but sitting in the bed of the truck).
Reason you need 3 is because with the WDH engaged, you can see what your true tongue weight is, and can't determine how much is transferred off the rear axles and to the front and trailer axles.If you don't have weights for "truck and trailer with WDH off", you can get a reliable estimate of TW by applying some physics and algebra to the results of the other two passes.
Even if you do have the loads from "truck and trailer with WDH off", you don't necessarily get an accurate measure of tongue weight.
If the hitch is depressed too much by the TW, the TT is in a "nose down" attitude and that can give an indicated TW which is different from the actual TW.
Ron
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Ron Gratz
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05/25/13 07:28pm |
Travel Trailers
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RE: Back from the scales
Your scales numbers indicate
the tongue weight is about 1150#
with approximately 150# transferred to the TT's axles by the WDH.
If you can transfer an additional load of 80# to the TT's axles,
you will transfer approximately 200# more to the steer axle
and will remove approximately 280# more from the drive axle.
Ron
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Ron Gratz
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05/25/13 06:15pm |
Travel Trailers
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RE: WD front end is light
SnGConroy,
I recommend that you start a new thread instead of tacking your questions onto this existing thread.
That way, it will be easier for responders to know which OP they are responding to.
The new thread will have your user name attached and you can give it a title which is appropriate to your particular situation.
Based on your post, it's not clear if you even have a WD (weight distributing) hitch.
Ron
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Ron Gratz
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05/25/13 02:08pm |
Towing
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RE: Thoughts on my scale numbers?
What is "not consistent"? Trailer without WD removed 420 pounds from front axle (3,500-3,080)---The raw data also indicate a tongue weight of 540#.
In this universe and on this planet, there is no way a 540# TW can cause 420# to be removed from the steer axle --
unless the TV's ball overhang is equal to 78% of the TV's wheelbase.
There's more to interpreting scales data than just addition and subtraction.
Ron
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Ron Gratz
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05/24/13 09:30pm |
Towing
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RE: Thoughts on my scale numbers?
Jack,
Here's the problem with the numbers:
The indicated tongue weight using TV only data and TV+TT with no WD is (3080+3700)-(3500+2740) = 540#.
Since the brochure hitch weight is 597#, it's quite unlikely that the loaded TW can be 540#
The initial loss of 420# on the steer axle is consistent with a tongue weight of about 1020#.
The initial gain of 960# on the drive axle is consistent with a tongue weight of about 680#.
Changing the "TV only" steer axle load to 3360# gives:
The indicated loaded TW is (3080+3700)-(3360+2740) = 680#.
This value is more consistent with a brochure TW of 597#.
The adjusted initial loss of 3360-3080 = 280# is consistent with a TW of 680#
A TW of 680# plus the TT axle load of 5080# gives a TT weight of 5760#.
The corresponding TW% is 680/5760 = 11.8%.
For comparison the dry TW divided by the shipping weight is 12.0%.
The adjusted net load reduction on the steer axle would be 3360-3280 = 80#.
Where were you positioned when the three sets of loads were measured?
If you were in/on the truck for some of the weighings and somewhere else for others, that could explain the discrepancy.
Ron
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Ron Gratz
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05/24/13 09:22pm |
Towing
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RE: Thoughts on my scale numbers?
How's it sit and tow? If you have it set up level and it tows smooth I wouldn't worry about.---Prior to 2011, Toyota said to adjust the WDH to "keep your vehicle level with the ground".
IMO, that's a very ambiguous specification.
In 2011, Toyota changed their WDH adjustment specification.
They now say to return the front to the same weight as before hitching.
Ron
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Ron Gratz
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05/24/13 06:10pm |
Towing
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RE: Thoughts on my scale numbers?
Jack,
The "Truck without trailer" steer axle load of 3500# is not consistent with the other scale values.
Were all three sets of axle loads measured with the same loading of the truck?
It appears there was about 150# of additional weight on the steer axle scale when the "Truck without trailer" loads were measured.
Ron
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Ron Gratz
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05/24/13 05:42pm |
Towing
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RE: Help with the math???
Acdcording to these 2013 FORD F-150 TECHNICAL SPECIFICATIONS,
the published payload capacity for a SuperCrew 4x4 157" EcoBoost with Max Trailer Tow Package is 1840#.
The published curb weight is 5797#.
I guess it's possible the "shipping weight" of your truck could be 200# below the "curb weight". However, the yellow sticker indicates otherwise.
The only way you can know the actual payload capacity is to weigh your empty truck and subtract that weight from the GVWR.
Ron
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Ron Gratz
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05/23/13 08:05pm |
Towing
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RE: WD front end is light
joshuajim gives excellent advice.
The bars do not need to be parallel to the A-frame,
but they do need to be perpendicular to the L-brackets.
If the bars are parallel to the A-frame,
but are not perpendicular to the L-brackets,
you will not have proper contact between bars and brackets.
Ron
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Ron Gratz
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05/23/13 09:12am |
Towing
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RE: WD front end is light
If the load on the TV's front axle is greater with TT attached and WD applied than when the TV is unhitched --
you have too much ball mount rearward tilt angle which is caused by too many washers.
Ron
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Ron Gratz
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05/20/13 08:30pm |
Towing
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RE: Anybody besides me using old school WD hitch?
---The only difference is that Equal-i-zer uses metal on metal friction while a sway bar uses metal on brake pad material.---That's true -- as far as the mechanism goes.
However, the Equal-i-zer has potential for creating several times as much sway-resisting torque as a friction "sway bar" can.
Ron
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Ron Gratz
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05/20/13 08:23pm |
Travel Trailers
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RE: Looking for better Sway Control
Darren,
It appears your trailer has an empty weight around 5000# and a GVWR of 7000#.
A realistic loaded weight would be around 6000-6500# with a corresponding tongue weight of about 800-850#.
WD bars rated at 800# should be sufficient.
BTW: Does your Armada have the auto-leveling suspension?
Ron
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Ron Gratz
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05/20/13 06:16pm |
Travel Trailers
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RE: new bigger tv, still need WD htich?
What is the maximum tongue weight printed on the receiver's label for "Weight Carrying"?
My 2004 Explorer says 500# -- would think your new F-150 could handle more than that.
Ron
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Ron Gratz
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05/19/13 06:06pm |
Travel Trailers
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RE: Equalizer hitch size, how big is too big?
---I deceided on an Equalizer wd hitch in the end. Customer service at Equalizer was very helpful and recommended their 1,000/10,000lb model.---Did you decide to get the Puma 25RS?
If so, the 1000# bars are a good choice since a tongue weight of 1000# or more is possible with the 25RS.
IMO, it's good that you did not choose Equal-i-zer's highest-rated hitch.
Ron
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Ron Gratz
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05/19/13 05:32pm |
Towing
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RE: CAMCO EAZ-LIFT
"With two links hooked I am down to being level on front end of tow vehicle but a 1/2 inch squat on rear."
IMO, this is better.
Ron
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Ron Gratz
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05/19/13 05:05pm |
Towing
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RE: Measuring grade on hills
---My little gauge indicates my rig is at a 10-degree attitude while climbing my driveway. That's about a 11% grade. Pretty steep for me to walk.A 10-degree slope is close to an 18% grade.
Hope that doesn't make it seem even steeper for you to walk. :)
The percent gradient for slopes from 1 to 10 degrees are given below:
Slope in degrees in column 1
Gradient in percentage in column 2
1 ____ 1.75%
2 ____ 3.49%
3 ____ 5.24%
4 ____ 6.99%
5 ____ 8.75%
6 ____ 10.51%
7 ____ 12.28%
8 ____ 14.05%
9 ____ 15.84%
10 ____ 17.63%
For small slopes, to convert degrees to gradient,
multiply slope, in degrees, by 100 times pi (3.1416) divided by 180
or, approximately 1.75% per degree.
The actual ratio increases as slope increases. At a slope of 45 degrees, which is a gradient of 100%, the ratio is 2.22% per degree.
Ron
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Ron Gratz
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05/17/13 06:56pm |
Towing
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RE: CAMCO EAZ-LIFT
---The tilt of the head assembly is all the way down if I put it in further the ball will rise. I am only down an 1/8 of an inch in the front and even in the rear.If you are an 1/8" down in front and even in the rear, you have transferred a little too much load to the front axle.
It's better to have the front a little above the unhitched height versus being a little below.
And, there is no need to return the rear end to "level".
In fact, since the rear axle should be carrying about 75-80% of the tongue weight, the rear should be below the unhitched height when WD is applied.
I agree with 93Cobra2771 -- you should remove one spacer washer.
Removing one washer will not have a significant effect on ball height, but will reduce the amount of load transfer.
Ron
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Ron Gratz
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05/17/13 01:00pm |
Towing
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RE: 3,500 max tow capacity.
In our pursuit of fine tuning our snowbird lifestyle we're getting down to a tow vehicle. DW has her heart set on a SUV that can tow 3,500 lbs max.What SUV are you considering? Can it actually tow a 3500# trailer, or does the weight of TV occupants and cargo have to be subtracted from the 3500#.
Casita makes a 13' Patriot which has an approximate dry weight of 1880#.
The axle capacity is 3500# which probably means the trailer's GVWR is 3500#.
You can ignore the GVWR unless you actually plan to load the trailer to that value.
Given the approximate dry weight of 1880# and your intended use (no boondocking), you probably can keep the loaded weight to less than 2700#.
Ron
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Ron Gratz
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05/16/13 06:33pm |
Travel Trailers
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RE: CAMCO EAZ-LIFT
Sounds as though you need to lift the TV/TT higher before hooking up the chains.
Are you using the tongue jack to lift the TV/TT?
If so, have you tried putting a block under the tongue jack so you can lift the TV/TT higher?
Ron
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Ron Gratz
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05/16/13 04:10pm |
Towing
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