Weighing Utility Trailer

[l008com]

I have a small 5' x 8' utility trailer with a 3500 lb trailer. It's been SUPER useful. I've used to to move more thing than I can count. And usually you just fill it up and go. But sometimes you're loading it with really heavy stuff, like old asphalt, old concrete, dirt, gravel etc. Stuff that could potentially overload the trailer. So I need a way to weigh the trailer.

I was thinking a lot about this and I realized that if you can measure the distance between the axle and the bed of the trailer, so basically how much the suspension is compressing, you'd be able to calibrate that with some known weight (probably just water), and you'd be able to use that system to know pretty accurately how much weight you've put in there!

It sounds simple but implementing it is a little tricky. The best idea I can come up with is a small steel cable, like a bicycle shifter cable, that would connect to the axle, then run up to a pulley connected to the deck, then it would move laterally to the front of the trailer, go up the front and connect to a spring that would hold it right. Then put a mark or indicator on it and as the suspension compresses, the indicator would move.

I could use small threaded stainless steel eye bolts as the guides for the cable and a stainless steel cable and it should do pretty well and not bind up. I would need to welt a little tab onto the axle.

Another option would be an electronic device that could measure the distance, then I could calibrate it the same way and use my phone to read it. Although I like the fully mechanical solution better, it's so simple.


Has anyone ever made a system like this? Or some other simple system to measure how much cargo you are loading on to your trailer? I'll attach an image. The yellow arrow should move up as the trailer's suspension compresses - as you add weight to it. And it should go down as you remove the weight. And the amount should be consistent. I have plywood sides I put on there if I'm carrying loose material. I could put them on there, throw a blue tarp inside, and fill it up with water. If I used some kind of accurate flow meter on the hose, I'd know exactly how much weight I was adding. I could make marks every 250 lbs and I'd have a scale that would work great for telling when I'm approaching or over or way over the ideal 2000 lb payload limit.

 

[Mooseman]

That is an idea. Don't know how accurate it would be though. For the initial weight measuring, you could go to a Cat Scale. They do allow a free re-weigh.

There is a device and app that may also work but because it's a smaller trailer, I don't know if it would work. I think it was designed for bigger trailers and reviews are mixed.

https://www.amazon.ca/gp/product/B081FTQCYN/?tag=gmtnation-20

https://www.amazon.com/dp/B081FTQCYN/?tag=gmtnation-20

 

[azswiss]

A simpler option would be to measure the distance between the spring eye bolt centers. As the load increases the spring will compress and the distance between the eyes will increase. Since you are really only concerned about being at or below the max limit you could determine what the max measurement is and then check as you load. Even simpler, establish the measurement between the back of the spring at the movable shackle end and a fixed point on the frame (e.g. a small piece of steel welded to the bottom of the frame).

 

[l008com]

The problem with doing it that way is that you're measuring a much smaller movement so it would tend to be harder to get an accurate measurement of it. Also I'm not really sure that's a simpler solution, it's essentially the same solution. Measuring suspension compression just at a different point.

 

[azswiss]

The problem with doing it that way is that you're measuring a much smaller movement so it would tend to be harder to get an accurate measurement of it. Also I'm not really sure that's a simpler solution, it's essentially the same solution. Measuring suspension compression just at a different point.

Agreed. That said, the objective is not so much accuracy as whether or not the load is approaching/exceeding the limit.

 

[Reprise]

You could try a trailer tongue weight scale. Yes, it's measuring the tongue, but if you figure that the tongue has roughly 15% of the weight, you can figure out how much the 'other' 85% is, and compare that to your 2000lb max. Here's one at etrailer that runs $95 Link
That one can weigh up to 2000lb (on the tongue), so it should be stout enough.

The better way is a set of portable scales. But they're expensive (like $1000 for cheap ones; most running about $2500 or so).

 

[6716]

Dig holes, pour footings, drop in tongue weight scales the same distance apart as your trailer wheels, drive up on it, and boom! You're in business. Prolly able to charge the neighbors while you're at it.

 

[gmcman]

Do you have a scale house near you on the highway? If so, give them a call and tell them you want to get weighed. Generally there's a position on the scale where you might get all 3 axles on a different scale and you can split the weight.

That's what I did with my Yukon and a dump trailer....no charge. I just went around 9 PM and it wasn't busy.

 

[l008com]

The closest highway scale I know of is the one on Rt 93 in Southern NH, and that's not very close and way out of my way and driving up there overloaded just to find out I'm overloaded kind of defeats the purpose.

There used to be a recycling company in town that had a truck scale, and I have emailed them before asking if I can drive on their scale at night, and they said sure. That's how I got the weights of all my vehicles and my boat/trailer. But they're gone now and even they are halfway to the recycling center anyway.

I like my suspension compression scale, I'm going to try to build that. And if/when I ever get new springs for the trailer, I'll just have to re-calibrate it.

 

[budwich]

you might consider your own "scale" using a bathroom scale and length of wood / pipe. Basically, you would set up the scale "pad" where the wheel rolls on it between two sections of cement (blocks / sidewalk stones, etc). The "wheel pad" would be wide enough to accommodate the wheel readily, width and length wise. The "pad" would sit upon the "lever" (ie. 2X8, or otherwise). The "fulcrum" point would be a piece of steel / angle iron at the "near end" (closest to the tire) while the scale and "measuring detent" (sitting on top the scale) would be out some "mathematical distance" to allow a proper reading on the scale.... 10 / 15 / 20 to 1. So if the fulcrum was 6 inches from the tire, then the "measuring detent" would need to be 60 inches ... you get the idea... I hope.

For "scale loading" (running onto the "scale", your "lever design" would be longer to allow a similar piece of angle iron to be used temporarily to take the "roll on / roll off" weight so that your bathroom scale in not physically "compromised" (ie. exceeding its weight limits).

Of course, your measurement results would be "doubled" since you are only weighing one wheel (the other is not on the scale, just on regular ground)... hence the 2X there after.

It might not be really accurate but that depends somewhat on the design.

I have used this technique to get an idea of the tongue weight on my travel trailer. It worked reasonably well. Of course, I was looking at weights in the 500-600 range so I only needed a 2-3 times ration and used plain 2X4 as my lever along with some cement stones along with a scale that was lying around.

It was an interesting science experiment that worked out well. I guess it depends on how much driveway room you have available to make the on / off "ramp".

I do like your "axle compression idea / setup" but thought I would throw out another technique.