How to gauge your trailer's tongue weight on an ongoing basis

[zzvyb6]

Get two bathroom scales from Salvation Army or Goodwill. Garage or Estate sales often have them for a buck. Place a 4x4 between them and park the tongue jack or coupler on the beam. Then add up the two weights. They don't have to be equal weights/position, just not maxed out readings.

Modern scales have to accommodate all the latest trends in body weight, so you won't be getting any more messages about "Please, Just ONE person at a Time ! " Use 3 or 4 scales if necessary by means of a small table with a scale under each leg.

 

[texasjohn]

Zing, exactly so.

Now, for extra credit, compute dynamic forces looking down vertically on the rig while going around a corner at speed and apply brakes hard because a deer runs out into the road. can you say "jacknife"

Not a pretty "sum of forces" picture...and why I MUCH PREFER a gooseneck trailer. All those forces are much better contained.

 

[thirdroc17]

Well... in the spirit of adding uselessly technical confusion to the thread... :laughing:

You guys are just talking about static force, when the trailer is sitting still. I have always wondered what is the difference when we look at the trailer in motion. How much force does the tongue experience when you hit a bump or worse when you hit the brakes? I took a random picture from the internet and put some arrows on it. When you are driving the force on the tongue would be steady, but when you hit the brakes (red arrow) the slowing force from trailer and truck braking is very low to the ground relative to the center of the trailer load. This would mean the boat inertia which is located much higher up (black arrow) is going to continue forward and try to pivot over the axle, putting a lot of extra downward force (downward arrow) on the tongue. Isn't it? As well, when you add the forces on the truck the truck braking will drive the front of the truck down and the back of the truck upward (green arrows).

I am not an expert, but it seems to me that the higher the load weight and the load center of gravity, the more force you would experience in a downward direction from the trailer tongue and at the same time upwards from the back of the truck due to braking, dramatically increasing the "tongue weight" at that moment in time.

Anyone actually know anything about this? Am I wrong about how the force is applied?

Just to add to the useless technical confusion, what about when towing an enclosed trailer? Wind resistance is pushing back on the top front of the box, thus unloading the ball weight......

 

[check]

Just to add to the useless technical confusion, what about when towing an enclosed trailer? Wind resistance is pushing back on the top front of the box, thus unloading the ball weight......

Do you guys lay awake at night thinking about all this stuff? Or is it the nightmares?

 

[CobyRupert]

A post placed horizontally off the ground between a bathroom scale and a block. The trailer tongue weight set on the post at measured percentage of the post length (e.g. 1/2, 2/3, 3/4, etc). Then use math

 

[tcartwri]

A post placed horizontally off the ground between a bathroom scale and a block. The trailer tongue weight set on the post at measured percentage of the post length (e.g. 1/2, 2/3, 3/4, etc). Then use math

Have you ever tried this? It is surprisingly inaccurate.

 

[CobyRupert]

Get two bathroom scales from Salvation Army or Goodwill. Garage or Estate sales often have them for a buck. Place a 4x4 between them and park the tongue jack or coupler on the beam. Then add up the two weights. They don't have to be equal weights/position, just not maxed out readings. Modern scales have to accommodate all the latest trends in body weight, so you won't be getting any more messages about "Please, Just ONE person at a Time ! " Use 3 or 4 scales if necessary by means of a small table with a scale under each leg.

Or just with one scale
Use a post placed horizontally off the ground between a bathroom scale and a block. The trailer tongue weight set on the post at a measured percentage of the post length (e.g. 1/2, 2/3, 3/4, etc). Then use math

 

[s219]

Have you ever tried this? It is surprisingly inaccurate.

I tried it once for weighing some steel, and it seemed accurate for me -- got my weight right and combined weight of me and my wife. As long as the scale is accurate and you do the math right, it should be pretty good.

 

[tcartwri]

I tried it once for weighing some steel, and it seemed accurate for me -- got my weight right and combined weight of me and my wife. As long as the scale is accurate and you do the math right, it should be pretty good.

I have experimented with it, and it was not accurate at all. Could not repeat the measurements no matter how carefully I set up the apparatus. So I bought one of the commercial grade scales and my best measurements with the bathroom scale were off by almost 200 lbs.. A 30% error.

 

[radioman]

I just eyeball the trailer levelness in relation to the ground after being loaded. If the front and back looks good and the rear is not sagging more then 10-20 percent in relations to front - I feel confident to go on the road and test the load.