Made a "Forklift Scale" for the working poor

Yes, it does, I just checked. It varies by 20 PSI. Not that big of a deal, and it is very consistent.

i
Reply to
Ignoramus32392
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Mine is like that, also. Just a little bit more work to make a conversion table.

i
Reply to
Ignoramus32392

The gauge is NOT oil filled.

i
Reply to
Ignoramus32392

OK, I changed the non-liquid-filled 3,000 PSI valve, for a liquid filled, stainless 5,000 PSI valve. I think that it will "do it".

Reply to
Ignoramus32392

That may work for you but be very careful if it needs to be very accurate, Forklift manufactures don't do it because of liability worries of a forklift tipping over. You need to know your weight before it goes on the forks.

Reply to
jeff

Paul, the name for that would be the Free Lift

Reply to
jeff

Actually, pretty sure most telescopic forklift cylnders are of the constant thrust/ constant speed variety; with each piston section having the same surface area.

If they were not, the mast lift speed would abruptly change as each cylinder section arrived at the end of it's respective stroke making it fairly difficult to accomplish a controlled lift.

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Reply to
PrecisionmachinisT

It does not need to be very accurate. Plus or minus 200 lbs, or 3%, whichever is greater, is fine.

OK, you got me. If I do scrap metal, how exactly do I know the weight before it goes on the forks?

The scale is the way to find out the weight.

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Reply to
Ignoramus32392

Hey Paul,

Yeah, but for "weighing" purposes, it will only be when "picking" the load and not when the mast is reaching extension..

Brian Lawson

Reply to
Brian Lawson

Brian Lawson fired this volley in news: snipped-for-privacy@4ax.com:

That's not the case with all lifts, even those with double and triple- section masts.

If the cylinder is not the telescoping variety, and if (as is often the case), the cylinder is lifting one or a pair of sprockets that lift chains that lift the mast (for obtaining multiplication of travel), then the cylinder is picking up the same weight from one end of travel to the other.

Only if the mechanical advantage or effective cylinder size changes does the pressure vs. travel change.

The telescoping of the mast itself is just to make it all fit in a more compact space when lowered (so it can go through doors).

LLoyd

Reply to
Lloyd E. Sponenburgh

The weight of each section of mast is added to the lift as each section comes into play and is no longer resting on the stops.

Reply to
Pete C.

Brian, it is actually both, as sometimes we need to lift something from the top with a chain, it happens often. I will just have two tables (or one table in two columns).

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Reply to
Ignoramus24728

My mast has three cylinders. One in the middle, and two on sides. Those two start extending only after the main cylinder has extended, and at that point the pressure rises something like 1.5 times.

i
Reply to
Ignoramus24728

I also pick up loads from the second level of the rack system. And I have added to the pallet box-by-box, over time, from a step ladder. I would not know how much it weighs until the fork lift picks up the pallet.

Paul

Reply to
Paul Drahn

Now you need to replace the gauge with a pressure sensor, some encoders to monitor mast height and a microcontroller that will display the load weight, lift height and mast clearance height along with programmable alarms so you can set the doorway/ceiling headroom and get alarms when you are about to hit the ceiling with the mast while you are busy watching the load...

Reply to
Pete C.

"Pete C." fired this volley in news:5162b879$0$6388 $ snipped-for-privacy@ngroups.net:

No doubt, but trivial compared to the sort of weights one would be concerned about. It's not a 'non-linearity', but a step function. (If you're on mast section 2, add 410lb, etc...

Lloyd

Reply to
Lloyd E. Sponenburgh

Not so trivial if it leads you to leave 1,000# of stuff for another trip when you could have finished the job and loaded the semi to rated capacity if you had accurate weights. That extra trip could cost hundreds of dollars in time and fuel, cutting into your profits. Iggy also needs to make a trailer load calc application for a laptop or tablet so he can enter the weight and load position on the trailer and see the calculated axle weights.

Reply to
Pete C.

I am in no way saying that it can't work, being in the industry forbids me to try because of liability issues. I do know that there is stuff out in the field to measure weight but its not cheap. If you can come up with something reliable then you may strike it rich, that is untill someone tips a forklift onto its face. I don't know what your data plate says about your forklifts capacity but would a portable scale work? Not trying to be negative but the fine for being over weight may be the least of your worries.

Reply to
jeff

There are forklift scales being sold by various outfits. Some are based on pressure sensors and some are built into carriages. Mettler Toledo makes them, and it is a respectable, well established company.

My own version is inferior in some ways, such as less convenient to use and less repeatable, but it cost me almost nothing. I had a pressure gauge that I removed from a big machine I scrapped recently, and a hose, I only had to pay for a tee fitting and size reducer.

I personally do not buy the story that forklift scales somehow make a forklift less safe. I also feel that the operator of the forklift should feel if he is overloaded or close to tipping over, by how the forklift behaves. And in that case, just keep the load close to the ground.

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Reply to
Ignoramus24728

I spent some more time on it today. I consider it to be finished.

  1. The pressure gauge is now mounted nicely and firmly in a place that is unlikely to be affected by load, chains and other forklift use.

  1. I figured out how to deal with errors caused by friction. It is very simple. I just need to take two readings, one after creeping the load up, and the other after creeping the load down. The average cancels friction out. Problem solved.

  2. I lifted another forklift on the forks of this forklift, took down pressures, and I now have a nice and easy conversion table, PSI to lbs.

  1. I realized that maximum pressure in the system is always well under

2,000 PSI (20,000 PSI would occur only if this 15k forklift tried to lift a 20k load). So, my oil filled 5,000 PSI gauge would have a great cushion against pressure spikes.

  1. Everything is neat and tidy, the pressure lines do not rub against anything, the gauge is easily visible, yet protected, etc.

I will probably put similar gauges on all my forklifts.

i
Reply to
Ignoramus26995

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