using a pressure guage as a scale.

[SPYDERLK]

I was curious about this because my experience at gut level indicated a much less pronounced effect on my ML275 loader. Im dealing with some stumps right now so I had good opportunity to test it yesterday.

I managed to get a ~ 1T stump in my bucket and raised it from ground to full height. 1100psi was good for a few feet, and then I had to use escalating pressure up to 1400psi to attain the 11' max height.​

On the surface this indicates an 11/14 force maintenance in contrast to ~1/2 in the graphs.

In conjunction with this real world scenario it has to be noted that the load point relative to the pins had to be changed a bit with height to prevent the stump from tipping back out of the bucket and killing me. This rotation uncurl of the bucket and rotation upward of the arms factor to change the lift point a little​

I think not a significant factor, but of course the best test would be to suspend the load or use a force gauge on a vertical tensile line. One loses test range and the other requires a nice force gauge and a good anchor point.

LD1, I would be interested in what your loader shows in a similar real world test. I know youll counterweight and be careful to watch bucket orientation while multitasking. Thats what makes it especially dangerous - the extra task. Im used to raising stumps to full height and dropping them to dislodge dirt. Watching a gauge concurrently is a distraction that is and should be scary.​

A set of forks with a log on would be ideal.

Different loader. But I assume you have a gauge tee'd into the lift circuit similar to how I had the one on my old L3400?

Because if this is the case, you are overlooking a very critical part of the calculation....

The pressure required to lift the dead weight of the loader itself.

On my old L3400, it was 600psi just to carry the arms and empty bucket.

So in your scenerio....if a similar 600psi is just the dead weight of the loader.....taking that out.....it took you ~500psi to lift the stump down low, and 800psi to full height.

5/8ths is a lot closer to what a typical graph indicates as opposed to the 11/14ths you observed on the surface of things.

Ah-h. Good catch!
​

I saw your reply last evening and waited 'til today so I could go out and experimentally establish the offset range

Were going to have to suspend disbelief on this for a little bit -- but mine lifts off at 250psi and tops out at 325. ... Repeated 3 times.​

Note the extreme similarity between 250/325 and 11/14!! Note also that this is a 5000PSI gauge so 250 - 325 is just off the peg. No trust there. Also this gauge has been in the pump output circuit for years and lost its glycerine fill about a year ago.

Since then Ive noticed lower indicated free flow pressures [vs RPM] in the hyd circuit.​

So the "trust" range is all over the place on this gauge. I will redo the test using an identical new 2000PSI gauge that I have and report back. It may not be soon. Have to get a replacement for the original and wait for a play day.

 

[dfkrug]

Shop around for a crane scale for your weight range.

Wow, those scales have sure come down since I built my hydraulic dangle-scale. I looked
at the time and there was nothing acceptable for under $100 as you have shown now.

Anyway, I bought a small new hyd tierod cylinder, and filled only the rod side with oil. A 600psi
glycerin-filled gauge and a grabber hook were the only other items purchased. I spent about
$40 total.

I welded up a connector to dangle from my FEL's chain hook. The grabber hook works with
all my chains. To calibrate it, I suspended a known weight, and figured the scale factor I
needed.

Works great.

As others have pointed out, using the FEL's boom cyl pressure as a scale is impractical as
the weight you are measuring has to be at the same point fore-aft and the loader at the
same height, on level ground. And the FEL's bucket curl has to be in the same position. There
are a lot of conditions!

 

[pmsmechanic]

As others have pointed out, using the FEL's boom cyl pressure as a scale is impractical as
the weight you are measuring has to be at the same point fore-aft and the loader at the
same height, on level ground. And the FEL's bucket curl has to be in the same position. There
are a lot of conditions!

I hope I'm not being to harsh here but have you not read anything on this forum? There are companies that make kits to put on fel's to weigh goods. It's not 100% accurate but if you go to post #1 all the op wanted was a "rough guide". Seems to me a "T" and a gauge would do that. You just need to lift to the same position for "rough guide" accuracy.

 

[dfkrug]

I hope I'm not being to harsh here but have you not read anything on this forum? There
are companies that make kits to put on fel's to weigh goods.

Then why don't you link to such a product to help out the OP, rather than being "harsh"?

 

[pmsmechanic]

Then why don't you link to such a product to help out the OP, rather than being "harsh"?

Post #17

 

[dfkrug]

Post #17

Sorry I missed your link. Nothing wrong with having a pressure gauge in the lift
circuit.

At $95, the digital scale posted by BCP seems to be the way to go. You can't escape geometry.

 

[pmsmechanic]

I wonder how the electronic scales that are made for fel's do it. They must have a position sensor that lets the computer calculate the geometry.

 

[LD1]

I wonder how the electronic scales that are made for fel's do it. They must have a position sensor that lets the computer calculate the geometry.

Maybe. Anything is possible.....how much money do you want to spend and how accurate do you need it to be.

The one you linked in post #17 clearly states

HIS SCALE IS A GOOD WEIGHT ESTIMATOR AND IS NOT “Legal for Trade”

That sums it up very well. Any type of gauge that references hydraulic pressure in the FEL circuit is good for an estimator and nothing more.

The most frequent uses I see for FEL scales like that are at the quarries where they load stone.

Big loaders used to loading 20t dumptrucks and in rolls someone like me in a pickup of dump trailer and only wants a couple of tons.....they can get close. Because they are always loading loose raw material, IN the bucket (not varying load positions like grapple, pallet on clamp on forks, boom pole load, load in bucket). And they also take their scoops low and are probably trained to take their reading at a similar height everytime.

Once calibrated these scales can be VERY accurate but ONLY if used consistently.

The variability of how we tractor operators like to use our front loaders is a big crutch for any type of weighing system that references hydraulic pressure. IF you are consistent, the readings will be accurate and consistent. The more you deviate, the more the accuracy deviates.

 

[pmsmechanic]

Read post #1! All the op wants is a "rough guide" as to the weight of a feed bag. So if he hangs the bag off the bucket and curls it right up and lifts the loader arms to the same point he should have a "rough guide" with a pressure gauge as to how much the bag weighs. It's quick, simple and easy and gives the results he's looking for. $15 -20 should tell him everything he wants to know.

I know it's not accurate enough for trade but that's not what the op is asking for. If you want more accuracy then just install a lower pressure guage with a valve in the circuit and only use the gauge when weighing feed bags. The rest of the time the gauge can be isolated from the work by closing off the valve.