Weigh results...

[SuiteWheels]

Would someone be so kind as to figure these weigh results out....we honestly don't know how. I know there has to be a post somewhere that tells us the steps but I'm on my way out and just too lazy to try and find it. Appreciate it....I'm sure we were overweight on our trip.

First weigh was 4360 lb GROSS (front of dully)

Second weigh was 11900 lb GROSS (complete dully)

Third weigh was 13500 lb GROSS (trailer)

[billr]

Ok, I'm Assuming the wts you gave are the truck with the trailer connected and those are the front truck axle, rear truck axle and both trailer axles combined?

To completely figure out your wts, you need to go and have the truck weighed without the trailer.

Once you get the rear axle wt of the truck without the trailer, then subtract that from the first wt of the rear truck axle (with trailer) and that will give you the Pin wt of the trailer.

Then you can add the trailer Pin wt and the trailer (combined) axle wt you got on the first weigh, and that is the trailer total wt.

Easy eh?? :shock:

Cheers,
Bill

[golf_bears]

As pointed out by billr, you did not give us enough information but we may be able to make a few assumptions.

I will make the same assumtions as billr and a few more, here goes.

Total combined weight of trailer and TV = ( 11,900 + 13500) = 25,400
Rear axle weight = (11,900 - 4,360) = 7,540

Now I will assume your truck's weight independent of the pin weight = 8,000.

If your TV weight = 8,000 your pin weight weight = (11,900 - 8,000) = 3,900.

If your pin weght = 3,900 then your trailer = (13,500 + 3,900) = 17,400

If your TV weight is more/less than 8000, adjust the numbers accordingly.

Hope this helps, have a great day.

[SuiteWheels]

OK thanks guys....maybe now he can figure this out! LOL

[Motor31]

First some questions, What kind of scale did you weigh at? Did each truck axle have it's own scale pad? Did you weigh the rig hooked up on all the readings? Did the trailer axles both sit on one scale pad?

The system I used was the truck stop scales. I weighed hooked up and ready to go on the road. Each truck axle was on a scale pad, the rears in my case both on the same pad. The trailer axles also on one pad. This gave a weight for front axle, loaded rear axles and trailer axles. I then took the trailer and dropped it off in the lot then weighed the truck alone, again with axles on their own pads so that I had a weight on the rear axles unloaded now.

Subtracting the unloaded rear tow vehicle axle weight from the loaded rear axle weight gave me the pin weight.

The only draw back to the truck scales is that it does not give side to side weights or each tire position weights. It is possible to be under the axle loading limit but be overweight on a tire.

[RodeWorthy]

I'm confused. A couple of posters have stated to determine the pin weight they subtract the unloaded tow vehicle rear axle weight from the loaded weight of the same axle. Isn't a portion of the pin weight resting on the tv front axle? If this were the case, would it not be more accurate to use the whole tow vehicle weight (loaded and unloaded) to determine pin weight?

[billr]

Don,

It does make sense to use the total wt change when loaded to determine pin wt, but in most cases the front axle wt is less when the trailer is on the truck. Mine is acutally 100lbs lighter on the front when hooked up.

Now, that should mean that 100lbs is transfered to the rear when loaded, so then is my pin wt actually 100lbs less than what I think?? The difference between my rear axle loaded and unloaded is 3450lbs but since the front is 100lbs less then it should be 3350?

When Stacey wieghed our rig the sheet shows the pin wt to be the diff between the rear truck axle wt loaded and unloaded, not the diff between the total truck wts.

I maybe shouldn't try to do this after a night shift!! :shock: :shock:

Cheers,
Bill

[golf_bears]

billr,

The fact that your front axle shifts 100 lbs to the rear axle when trailer is hitched up, does this suggest that your hitch may be slightly behind the rear axle? Or perhaps the rear suspension is sagging and changing the angle of the truck from level to slightly lower in the back and therefore shifting the center of gravity towards the rear axle?

What do think? I’m curious?

[Motor31]

With a tow vehicle you are going to get a shift in the CG by hitching up as long as the hitch is far closer to the rear axle than the front. Being a few inches forward of the rear axle isn't going to change the shift all that much since the load is still several feet behind the center of the vehicle. In the case of an MS and other heavy rigs, it's a significant load.

[Stripit]

The true pin weight is based on what a truck weighs without a trailer attached, and what it weights with the trailer attached. Perfect world front axle remains the same weight. Have seen as much as a 400lb swing in front axles loaded or unloaded. Some people believe that it is only a rear axle thing, but that is inaccurate.

[Stripit]

darn gremlins

[golf_bears]

Stacy,

You are correct with your comments about “the true pin weight”. In my example above that is exactly how I calculated the pin weight making the assumption about the truck weight (If your TV weight = 8,000 your pin weight = (11,900 - 8,000) = 3,900). Had the true truck weight been given, we would have been able to calculate the true pin weight.

Take care and drive safely

[billr]

I agree with what Mike said about CG shift.

My hitch is located ctr on rear axle and have little sag, truck above level in rear.

Also the True pin wt calc is also accurate but even if the True pin wt ends up being less than calculated using the total truck wt diff, you still have the actual load applied to the trucks rear axle whether that is actual pin wt or some of the front wt transfered back.

We need to take that into account when loading rear axles and tires.

So in theory, the total truck wt method is valid for actual True pin wt, but for application purposes, we should use the rear axle calculation method for applied wt to the axle.

Stacey, that must be why you do the calculations on your weigh sheets the way you do??

Does that make sense? Now I'm just wakening up!! :lol:

Cheers,
Bill

[RodeWorthy]

Bill and Mike I respectfully suggest we are talking about two different things here. If one is interested in the trailer pin weight, which is a dead weight not subject to dynamic forces such as CG, then the entire vehicle weight differences should be used to determine that weight. The total weight applied to the truck when hitched is the pin weight and it doesn't matter where that weight is distributed on the tow vehicle.

If we are discussing dynamic loading on the tow vehicle axles then weight transfer comes into play and CG can be a factor. So can pot holes in the road. This would not be an easy calculation to make.

Both sets of information are important but they are different.

[billr]

Actually Don, we may have side tracked a bit here, but the CG shift we are discussing is static, no dynamic loading, that would be indeed a difficult task to determine.

The bottom line is the load applied to the rear axle is the difference of the loaded and unloaded rear axle, and that is what the trailer is putting on the trucks rear axle. I suppose that the true pin wt could be calculated a few ways but not very helpful in regards to what loads we have on the truck.

Ok, now my head hurts!! :lol: :lol:

Gotta go fix my broken slideout!

Cheers,
Bill

[Stripit]

Bill; What I was trying to say, is many times the front axle is gaining hundreds of pounds when attached to the trailer. Just using the rear axle will not show the entire picture of what 'might' be happening.

[Motor31]

Rodeworthy,

A "dynamic" weight shift is going to be rather difficult to calculate. I am assuming you mean the weight shift that happens particularly upon brake application. At least that's what I think you were referring to.

That is going to depend on a number of variables such as speed of the rig, condition of the brakes, actual amount of application of brake power for each vehicle, pavement condition, coefficient of friction of the pavement, weight of each of the vehicles in question and tire condition to include temperature and pressure. The amount of weight shift would change each time any of those variables would change.