Tandem Trailer Geometry

[em14]

J_J - That's an interesting site ... thanks ...
Leo

 

[Egon]

How many of you think that a balanced load is when the load is centered over the axles. Raise your hands. Now , put them down.

Yes Sir!

But Sir; is not a a balanced load equal on all sides Sir!

 

[J_J]

Yes Sir!

But Sir; is not a a balanced load equal on all sides Sir!

You probably know all this, but sometimes a balanced load is not equal on all sides. You have to state a reference point. If you don't think so, balance your load equally, and then tell me it is balanced for towing. I know you would like to continue this, but I would rather not.

 

[Reg]

How many of you think that a balanced load is when the load is centered over the axles. Raise your hands. Now , put them down. Sometimes it is very hard to know when the load is situated right to give the proper towing response, and that is a smooth pull, with no fishtailing, etc. No matter what kind of load you have, you have to consider the load on the tongue, and it should not be above the rated load or above what the hitch is designed for. I believe you can cheat a little if you use the equalizing hitch to get the right load on the front tires, which is where you lose proper steering. The sway bar is another accessory that is useful . Too much weight on the tongue will push the rear end down thereby raising the front wheels, causing steering problems. It does take some effort to get the trailer set up right, be it trial and error, or whatever. I have pulled different kinds of trailers, with different vehicles, and that does not make me an expert, but it is just my opinion on things. Don't forget correct air pressure. But also consider an unloaded trailer being pull a long distance will give a better pull if you let out some air to keep the wheels from hopping and bouncing.

Right;
Measure the distance between the axle center lines.
Measure the distance from the front axle center line to the coupler.
Do the arithmetic you learned in lo skool fizix to fiure out where the C of G is for 10, 11, 12,,, up through 15% tongue load.
Even on a very short trailer it will be ahead of the front axle's center line, in my particular case 11% or more - this will be more so the longer the measurement from coupler to front axle.
This arithmetic ASSUMES that the axles are evenly loaded and you might have to play with ball height to make that so.

 

[Egon]

You probably know all this, but sometimes a balanced load is not equal on all sides. You have to state a reference point. If you don't think so, balance your load equally, and then tell me it is balanced for towing. I know you would like to continue this, but I would rather not.

Yes; to continue scientific facts may have to be compromised!

Yes Sir, continuation for the sake of scientific facts may not be in order Sir. Yes sir:

 

[Willl]

If you don't have enough tough weight

How can you tell how much you do have ?

For example, when loading my tractor onto my trailer, how do I tell how much forward to park it ?

Measure the amount of sag on the rear of the truck ?

How many actually drag your tractor/trailer/truck package down to the scale house to get real numbers ?

 

[J_J]

How can you tell how much you do have ?

For example, when loading my tractor onto my trailer, how do I tell how much forward to park it ?

Measure the amount of sag on the rear of the truck ?

How many actually drag your tractor/trailer/truck package down to the scale house to get real numbers ?

This is one way using a bathroom scale.

http://www.curtmfg.com/index.cfm?event=pageview&contentpieceid=1347

Tongue Weight

 

[Diamondpilot]

How can you tell how much you do have ?

For example, when loading my tractor onto my trailer, how do I tell how much forward to park it ?

Measure the amount of sag on the rear of the truck ?

How many actually drag your tractor/trailer/truck package down to the scale house to get real numbers ?

I do. I have a gravel pit 1.5 miles from my house so everything I own has been weighed. I then mark that weight on each item with a label maker. I do all my trucks with just me in it and 3/4 tank of fuel, I figure that is a good average since I never go below 1/4 tank.

As for loading your eye will tell you if its ok. You want the tow vehicle to sag a little so you know it has weight on the hitch but not so much it starts to lighten the front wheels, this is dangerous. I have had to take cars off and back them on to find a happy spot on the trailer. With experience you will get a feel for things. My tractor for example rides much better backed on the trailer.

Chris

 

[J_J]

Looking at the picture of the commercial tongue weight device, could you not make something using a cylinder with oil in the lower part and install a 1500 psi hydraulic gage in the hyd fitting on the lower half, and be able to sit the tongue on the shaft of the cylinder and be able to read the tongue weight. Chock the wheels first.

 

[Willl]

Anybody ever done the bathroom scale trick ?

 

[Skyco]

Looking at the picture of the commercial tongue weight device, could you not make something using a cylinder with oil in the lower part and install a 1500 psi hydraulic gage in the hyd fitting on the lower half, and be able to sit the tongue on the shaft of the cylinder and be able to read the tongue weight. Chock the wheels first.

Yep I did just that. I put a gauge on my HF portopower clone so I could tell how much force I was applying to things. Then I found one of my smaller rams was right close to 1 square inch ram area. Voila! Instant scale. The one square inch makes it easy to read weight directly on the pressure gauge. I put the ram under any trailer coupler and see what it takes to lift, that is the actual weight measured on the gauge. Any size ram will work but then you have to do the math if it isn't 1 sq inch to convert.
I used it to great advantage figuring out how to position my motorcycle, atv and Bx24 all in an enclosed trailer. Turns out, motorcycle and atv go side by side in the front then the tractor is backed in. Due to weight of the backhoe pulling it in forward resulted in too little tongue weight.

 

[Egon]

How many actually drag your tractor/trailer/truck package down to the scale house to get real numbers ?

I have. More than once.

 

[Willl]

Would this be to little tough weight ?

YouTube - Oops!

 

[Oldmax]

You should have 10 % of trailer on tongue. an if trailer is over 3000 LBS should have equlizer hitch to add height back to front of TV .

 

[Willl]

Anybody ever done the bathroom scale trick ?

Well, tried doing just this today. And failed.

Actually, trying to use a electronic bathroom scale is what messed me up.

Between getting the thing to self calibrate, then lowering the tongue on to it before it timed out was to much.

I'll try again later with an mechanical one.

 

[J_J]

Well, tried doing just this today. And failed.

Actually, trying to use a electronic bathroom scale is what messed me up.

Between getting the thing to self calibrate, then lowering the tongue on to it before it timed out was to much.

I'll try again later with an mechanical one.

How heavy is your trailer? Are you trying to set the tongue on the bathroom scale, or you doing the off set method as mentioned in previous post.

I would recommend that you jack up the trailer higher than level, and set up the cement blocks or wood, and then lower the tongue onto the wood timber and multiply accordingly. The trailer should be level when you are measuring for the tongue weight.

 

[Willl]

How heavy is your trailer? Are you trying to set the tongue on the bathroom scale, or you doing the off set method as mentioned in previous post.

It's a 8000# tilt. It's in my photobucket if ya want a peek. (note the JD green pin striping )

I was using the "1foot-2foot times 3" method that I posted a pic of earlier.
See the little circles they call "pipes", they should of called them 'wheels'.

My main problem was the amount of time the electronic scale gave me between 'calibration and read-the-weight time'. Way too short.