Scale system for dump trailers ?

[FredH]

Per the title , anyone know of a on board scale system for dump trailers . I know about onboard systems used on semi's , basically is connected to airbag system thus uses pressure , but with most smaller trailers and dump tailers , they are all leaf spring systems .

If nothing commercialy available , I see a project in my future . Thinking that I could get a set of airbags , make my own brackets to install . and add minimal air to snug up bag or bags . Have a pressure gauge also installed on system . When trailer is empty , bag would be XX psi . Thus dump 4000 pounds in , bag would be compressed and psi would go up . It would take a few loads to get a calibration rate , but after that it , it would be simple to look at pressure gauge while loading and wave the hand to stop when pressure is reached .

I get a lot of my various rock products straight from the quarry . You empty weight going in , then loaded going out . When products like decompsoed granite or sand / gravel cement mix get rained on for a week or 2 , they tend to get a little heavy , thus cannot rely on " Looks " or even bucket size of loader .

Thoughts ???

Fred H.

 

[Looking4new]

I've never heard of a weight system for spring ride trailers, but that doesn't mean they don't exist.

I just look at my tires, when they look like they are half flat I've got enough. I had 1200 lbs (according to the DOT scale that wasn't manned) on my M101CDN2 the other day. Just a tad overweight, but it hauled like a dream.

 

[bcp]

Shouldn't be too hard to make a mechanical device that measures the distance between frame and axle. Then calibrate it with known weights.

Bruce

 

[dannoGT]

How about a 2 dollar harbour freight tape measure? And check the distance from bottom of trailer to the road? That's my quick check on the pickup?

 

[FredH]

Yesterday I got another load of granite from the rock pit . Scaled empty going in with my 2006 ram 2500 quad cab LB ( hemi 4 wheel drive ) and Big tex 12' dump . Empty weight 10,860 . Large loader was having radio issue's , so another guy came over with a smaller skip loader / tractor to load . 2 full bucket loads looked close but ?? Pulled onto the scale and was a tad over 19,000 . Trailer was 30 pounds over for its rating , ( On the other hand , a few months ago same load type , granite , and load looked size wise , the same , gross was over 21,000 :shocked: ) . Trailer handled that overload fine , lifted it without a issue and over all , sitting on level ground , pickup and trailer looked like I was hauling bark instead of granite . Looking at tires is ???? since while in the rock pit , nothing is level .

I'll have to think about this some . Patent pending on My airbag idea , so nobody steal it please :laughing:

Fred H.

 

[David_Kb7uns]

Yeah you gotta watch going to the pit, got 1/2 scoop and was well at the 14k for trailer and load.

As you know the chip trucks in Oregon run air scales. Up around here most of the log trucks do not run air bags and they are using spring suspension so they put Load Cells on the bunks that hold the logs and they just weigh the logs as everything else is the same.

Did quick search and found this site and they have all types of load cells

Vulcan Onboard Scales, Logging Truck Scales - Timber

Hitch with weight gauge.

Weigh-Safe Trailer Hitches - Towing Peace of Mind

Maybe do something on the springs or just the dump bed, I have seen a trailer hitch stinger with a pressure gauge built in so that would do your tongue weight or just weigh the whole box on the trailer.

David

 

[FredH]

Yea , seen the Vulcan site with the load cells . Was not to sure the size , although I read one that was for 4" tube axles ???

My airbag idea would not be a overload or spring assist type , rather I would barely have it contact a upper plate at say 10 to 15 psi . Then as it was compressed , it would increase pressure at a gauge , thus would just have to remember readings . The remembering readings would likely be the hardest part at my age

Fred H.

 

[George2615]

I'm following this as I'd like to see the weight in the dump trailer before hitting the scale. about a month ago I picked up a few loads of bank run. 2016 Chevy 2500 crew cab 4x4 6.0L and 16' dump trailer. Empty weight was 12,040. Gross weight coming out for 4 loads was 21,240, 22,360, 24,440, and24,460. Truck hauled it fine and trailer tires were hardly squatting at all. Last 2 loads exceeded the trailer limit but box wasn't full and didn't look overweight. Luckily I only have a 3 mile trip to get it.

 

[David_Kb7uns]

The load cells I have seen on the bunks are about 1 1/2 inch square range and they are machined out and the sensor is made inside.

Have a couple of the Sherline Tongue scales and they are just a 1 inch piston with a pressure gauge hooked up.

This would be subject to the load distribution in the bed but could you put pressure gauge on the hydraulic pump for the dump cylinder and see what it is when the bed starts to lift.

You could just go visit your local ODOT motor carrier enforcement person and borrow his "jump scales"


David

 

[TMGT]

The local quarry by me sells by weight, their payloader has a scale built in that is apparently very accurate, I get 10k which is about max for my trailer and out of 2 loads on was dead on and the other was within 20 lbs of the target weight.

I still need to figure out the weight of the dump trailer by its self.

 

[BKBoiss]

Gravel haulers around here use the load cells like us log haulers do. A set at the back of the dump box in place of the hinges and a set at the base of the lift cylinder. They just raise the box 5-6 inches when they are ready to load and presto. Our old jeep and pole set ups had all load cells and were usually within 50-100kg every load. The new hayrack rig ups we all run now have load cells under the fifth wheel and run off the air bags on the trailer. The front is always spot on but those air bags are VERY temperamental. While your plan sounds good in theory my opinion from what I've experienced is that you would end up with more hassle then it's worth. Load cells and all that goes with them are very pricey. I think you have a good start but instead of using bags and a pressure gauge why not just rig up a "gauge" of sorts on the axels that you can look at and shows you the distance that the suspension has squatted. Then of course either way you go what you have for weight on your hitch would still be the wild card. Sorry I got long winded. I'll be watching this to see what works, you have got me curious now.

 

[fried1765]

The local quarry by me sells by weight, their payloader has a scale built in that is apparently very accurate, I get 10k which is about max for my trailer and out of 2 loads on was dead on and the other was within 20 lbs of the target weight.

I still need to figure out the weight of the dump trailer by its self.

Hook your empty trailer to your truck, and go to the scales to get a total empty weight.
Take your empty trailer off, and weigh just the truck.
Subtract truck weight from total truck with trailer weight.
Now you have your trailer weight.

 

[TMGT]

Hook your empty trailer to your truck, and go to the scales to get a total empty weight.
Take your empty trailer off, and weigh just the truck.
Subtract truck weight from total truck with trailer weight.
Now you have your trailer weight.

I know how to scale it, I just need to get around to doing it, I have access to a scale at the refuse transfer site that I work on their equipment at times.

Last scale with the truck/trailer was about 11k empty, trailer should be around 3k empty.

 

[bcp]

Didn't some pickups have a height sensitive load sensor for balancing braking effort?

Bruce

 

[TMGT]

Toyota did I know, can't remember all the others, a handful of other other Japanese trucks did I believe.

 

[bcp]

A Google image search found these.

pickup load sensor brakes - Google Search

Looks like a mechanically operated hydraulic valve. They would have figured out a good mechanical method of actuating the valve. Maybe a similar mechanical method could be used to move a pointer.

Bruce

 

[TMGT]

The only problem I see with using height/squat is that it's very dependent on load distribution, you would need to do a 3pt measurement and, since the springs are progressive, some good data points to calculate the load, plus a solid flate surface to measure on.
Might give you a general idea once you get ebough data points but won't always be easy due to terrain and still won't be very accurate.
I guess it depends on what your trying to achieve but it sounds like it won't do what the OP was trying to accomplish.

 

[FredH]

On my semi , there a 4 air bags . With a empty trailer hooked up , pressure is a given amount . As load weight increases , the pressure gauge also shows a increase in pressure . Having actually scaled a load that ended up being right at the given limit for the drive axles , 34,000 ) , I made a pen mark on the gauge in the dash . Now when ever I hook to a loaded trailer , I can look at that gauge and if below mark , I won't even scale the load unless I feel there may be a problem with the trailer axles .

Thus My idea of using 2 smaller type airbags , similar to the airlifts I have on my pickup . Even if I made my own brackets and centered 1 bag on each axle under trailer , then only applied a minimum amount of air to bag , ( say 10 or 15 psi ) , As load increased , pressure in gauge would also increase , at least that is what my feeble brain is telling me ??????? .

Minimal air in bags would thus not actually be a overload type spring and should not really interfer with leaf spring operation . I know if I do not add any air to the pickup bags , ( their minimum pressure is 15 - 20 psi ) , Pickup acts like it always did under a load .

Fred H.

 

[vsteel]

I would bet that you could do it with a tape measure. I have found that for most of the range that the springs are used they can be considered linear. For example on my pickup when I load the trailer I have found that 300lbs is an inch of movement at the hitch ball.

So what you do is find out what movement you have at the hitch for a certain weight. Then you find out what an inch of movement weights at the trailer axle. You then add them when you load the trailer. It won't be exact but if you are just getting close it will work.