max tongue load / position of axle

[Sumner]

You can get close to the tongue weight at home....



....using a bathroom scale....

http://www.curtmfg.com/index.cfm?event= ... eceid=1347

I've used this, but never checked it against commercial scale,

Sum

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

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[kitcat]

Perhaps I'm being a bit slow here, but it seems to me that weighing the tongue on a 4 wheel trailer isn't quite as easy as it seems. Let me explain.

If you have your loaded trailer, placed on level ground and unhitched. With a 200-300lb load on the front it should drop down to the ground, but it won't because the front axle is taking the weight, similarly if the tongue is lifted and scales placed under the tongue [using a small peice of wood] the weight again will be inconsistant because of the resistance from the rear axle. So neither will give a true weight.

The only way is to lift the trailer between the axles, so all the wheels are clear of the ground and then weigh the tongue.

Does this make sense or am I just spouting rubbish?

Paul

[Tomfoolery]

Perhaps I'm being a bit slow here, but it seems to me that weighing the tongue on a 4 wheel trailer isn't quite as easy as it seems. Let me explain.

If you have your loaded trailer, placed on level ground and unhitched. With a 200-300lb load on the front it should drop down to the ground, but it won't because the front axle is taking the weight, similarly if the tongue is lifted and scales placed under the tongue [using a small peice of wood] the weight again will be inconsistant because of the resistance from the rear axle. So neither will give a true weight.

The only way is to lift the trailer between the axles, so all the wheels are clear of the ground and then weigh the tongue.

Leaf springs with equalizers will not significantly change the load on either axle as the tongue is raised and lowered. The equalizer simply rotates, allowing the axles to traverse uneven ground while still carrying load, virtually unchanged. As long as you haven't run out of range of motion, the load is shared.

Torsion spring axles are different, though, as each one is completely independent of any others, other than attachment to the frame. With those, as you could climb over a bump, the axle on the bump takes more load, and the other takes less, regardless of how small the bump is.

Does this make sense or am I just spouting rubbish?

As far as torsion spring axles go, or any other independent suspension system for that matter, you're spot on. For equalized suspension systems, I'm afraid you're spouting rubbish.

Pic is of a powerboat on a trailer with the bow cranked up a little high. Equalizer is tilted a little, but the axles will carry the same load.



Second is of my trailer with the front axle on a jackstand (or bow low), while I was retrofitting disc brakes. An extreme example, but it demonstrates the principle.



Torsion spring axles, on the other hand, have no such interconnection, and have to be clocked so that they both carry the same load for a given frame orientation (level, presumably), and changing hitch height would mess that up, as you suggested.

http://www.dexteraxle.com/torflex_axles

[Sumner]

Perhaps I'm being a bit slow here, but it seems to me that weighing the tongue on a 4 wheel trailer isn't quite as easy as it seems. Let me explain. ....Does this make sense or am I just spouting rubbish? Paul

My experience is that tongue weight isn't quite as sensitive on a 2 axle trailer vs. a single axle trailer. Now saying that I once had this...



...U-haul loaded to the ceiling front to back and was towing about 500 miles with it. In the first 20 miles it was a real handful with easily induced sway. The last thing I had loaded was about 75 lbs. of some large decorative rocks right inside the back door of the trailer. I took those out after the 20 miles and put them in the bed of the pickup and the trailer towed fine after that. Sometimes it isn't much between having a trailer that tows well or doesn't,

Sum

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Our MacGregor S Pages

Mac-Venture Links

[kitcat]

Yes, my trailer has independant rubber torsion sprung axles called 'Indespension' units, not sure if you have them in the States, most double axles trailers over here tend to use them as they are easy to install and take up very little room.

So, if I jack up the trailer at exactly the halfway point between the axles, put the tongue onto a pair of scales, then I should get an accurate readout of my tongue weight? I use a Toyota Hilux pickup truck, with a towing limit of 2,750kgs thats about 2.75 tons, but the ball hitch is only rated at 75kgs, as are most ball hitches/towbars on the average small truck or big car/SUV, so unless necesary it doesn't seem a good idea to put too much weight on it, just enough to stop the dreaded snaking

Paul.

[Hamin' X]

If you can find a truck/commercial scale that you can use, weigh the tow beast with the boat hooked on, but do not have the trailer axles on the scale. Then drop the trailer and weigh only the tow beast. The difference in the weights is your tongue weight.

~Rich

[kitcat]

Of course it's so easy when you know how. Thanks Rich.

[Tomfoolery]

So, if I jack up the trailer at exactly the halfway point between the axles, put the tongue onto a pair of scales, then I should get an accurate readout of my tongue weight?

I would put the truck and trailer on flat ground, connected, then measure the height to some point on or near the hitch that's easy to measure to. Then, take the truck away, and put a 2x4 under the hitch ball area, with the other end on a scale (or use a scale and a 2:1 or 3:1 balance, if the tongue load exceeds the scale's capacity), and adjust the 2x4 on the scale by cutting or shimming (or clamping - you're not talking about much force here) so the height measurement when it's on the truck is the same.

This will duplicate the actual towing conditions with the truck suspension somewhat squatted, including any trailer axle imbalance, and give you an accurate tongue weight. Try a few different heights to see how much of an effect the axle imbalance has on tongue weight.

[ROAD Soldier]

Hello
I have an new incl. original aluminium trailor.

Now I guess that tha tongue load is too havy. Here in switzerland I should not have more than 75kg (165lbs).

So can anyone tell me, how far from the tongue the axle is fixed? I will bring the axle more in the directon to the tongue. But I have no idea how to define the right position (maybe I just have to check out by testing different positions, but this takes more time .

Thank you for any help kurz

by the way: a 60hp mercury is mounted

OMG now I know why my grandfather left Switzerland and immigrated to the USA. Use the KISS (Keep-IT-Simple-Stupid) concept just move what ever you have inside the boat aft until you can just lift the trailer tongue. If unless you are really old, a 150 pound weakling, or disabled this should put you in that 165 lbs range. Remember to use the 10% rule at all times. Which is in order to operate equipment of any kind you must be 10% smarter than the equipment you are operating. Also don't forget that metric system to American standard system conversion, for I would not want you to try and lift 165 kilos. Now if you can lift 165 kilos with no effort I sincerely apologize for any thing I just wrote that offended you, and please don't hurt me.