Hydrostatic quirk or total nonsense?

[jeff9366]

Now to clarify a bit: the FEL (or anything else driven via the hydraulic pump) will have more lift capacity at higher rpm.

This is incorrect. Increasing engine RPMs increases speed of FEL movement in feet-per-second but does not increase lift capacity in pounds.

 

[Egon]

The original article was total nonsense.

 

[Jims1025R]

4) I found the lift capacity at height X, and cheated it just a tad with the curl function.

Bear in mind that the "capacity" and lift ability are not always the same for a loader (bucket or forks). The geometry of the various angles of loader arms, bucket/forks position, and hydraulic cylinders means that there will be different lift ability based upon all of these angles, where the "capacity" will be the most conservative of the lift ability. This is not a suggestion that the capacity should ever be exceeded, and a well set up system will bypass hydraulic pressure, before capacity is exceeded (so the lift seems to stall). So you may feel that you have a little more power to load or lift a little with the loader/bucket/forks in certain positions, but the lift cannot be continued (at all, or safely). When you're operating in this range, you're pushing your luck - particularly when fork lifting something out of a truck and down to the ground. At least loading up can warn you and you can return the load to the ground.

Increasing engine RPMs increases speed of FEL movement in feet-per-second but does not increase lift capacity in pounds.

Correct. Increasing engine speed will increase hydraulic pump speed, and thus hydraulic speed. The maximum hydraulic pressure is limited by pump efficiency and hydraulic relief setting. If you are driving at any speed, particularly in high range, that is consuming some engine power, and may reduce hydraulic lift ability. If you are driving at anything other than a slow approach speed while operating hydraulics to their lift capacity, you're pushing your luck - drive or lift, avoid doing both at once!

I built a three point hydraulic log splitter for my JD tractor decades back. I plumbed in a log splitter valve to the tractor to power it. (The first valve had a kick out return, which made the tractor loader unsafe - separate story). The splitter worked, but not great. I used it - fine.... The I bought a dump trailer from the JD dealer for the tractor, with the agreement that it would "dump anything!". No, it wouldn't lift and dump a load. I investigated... There was an un marked pressure relief bypass in the splitter valve. I put a hydraulic pressure gauge on the valve output ('should have done that at installation!) and reset the relief pressure to that of the tractor system (it had been less than half). Well, the dump trailer became a near catapult, and the splitter would split the big maple after all!

If in doubt, ask your dealer to check the hydraulic system pressure and relief setting, and give you a little more review of how the hydraulic attachments work...

 

[mikester]

NOTE TO OP

Your SCUT is NOT a skidsteer. Your SCUT is NOT a forklift.

Rated lift capacity for your machine is at the pins without bucket or forks. Your lift capacity changes based on the height of your lift. Your max lift is near the ground, is lower at 4 feet, is lowest at max height.

Put on forks, deduct the fork weight from your lift capacity. Same for the bucket. The further your load is from the pins, the less you can lift.

Digging from the ground or a pile is hard work. Digging from the bottom of the pile is even harder work for any machine. Your machine wasn't designed for this work.

Bottom line is if your machine can't lift or push something then you are using the wrong machine and/or you have wrong expectations.

 

[Diggin It]

So . . . I have a B2601 with pallet forks. I have sometimes run into problems lifting "stuff" which I know weighs less than the FEL rating. The engine doesn't bog, but the FEL won't lift. I was unloading freight on pallets out of a tractor-trailer, and the FEL wouldn't lift, but it would curl, and that gave me enough clearance to get the pallet out of the trailer, back away, and lower the pallet to the ground.

What do the forks weigh? Rated lift capacity might be without either bucket or forks.

How far forward of the pins was the load? Closer in, more lift. Farther out, less lift.

Digging from the ground or a pile is hard work. Digging from the bottom of the pile is even harder work for any machine.

I've also found I can curl more than I can lift. That helps when 'breaking out' of a pile of gravel. Move in, curl to break, then lift. Something about using the heel of the bucket for leverage I guess.

 

[jeff9366]

Bottom line is if your machine can't lift or push something then you are using the wrong machine and/or you have wrong expectations.

BUY ENOUGH TRACTOR​

 

[sunandsand]

I was unloading freight on pallets out of a tractor-trailer, and the FEL wouldn't lift, but it would curl, and that gave me enough clearance to get the pallet out of the trailer, back away, and lower the pallet to the ground. The truck bed is 4' off the ground, maybe a little more.

It is much safer in max lift unloading situations to raise the load an inch, then have the someone drive the truck out from under the load, then lower the load with the tractor stationary.

That initial 60" of tractor movement at max lift is the most dangerous time, when tractor rollovers occur.

Absolutely agree.

Tractor-trailer guy arrived, opened the roll-up door at the back, went to the cab and went to sleep. He's done until we're done. (Standard trucking company policy). I was and I am very, very careful to back STRAIGHT out, on a firm and level surface, and then get the load down as expeditiously as possible. Then, once the load is safely down, a few inches off the ground, I'll start driving it around into the warehouse.

I have a bigger problem with "helpers". Dear Bride likes to take photos of this in progress. I tell her to back up, and she does - about two feet. I tell her to back up again, she gets mad. (Better mad than hurt or dead.) I had someone walk between the tractor and the trailer, I yelled at him not to do that, you wanna get hurt? and five minutes later he did it again. I have to "control" the work space, and sometimes people just. don't. listen.

Best regards,

Mike/Florida

 

[sunandsand]

The pallet forks weigh about 100 pounds - they're from Everything Attachments. The pallets are "euro" pallets, which are slightly smaller than standard US pallets.

I don't anticipate this occurring again. I get two containers a year from overseas. Usually, the contents are fabric and wood items and are light. This time, he decided to also send some pottery items, which is basically rocks. His consideration is to fill the container, he needs to "cube it out" to minimize his per-item freight costs. What he did this time was "grossed it out", he filled the container with heavy stuff right to the weight limit of the container (and to the weight limit of the lift capacity of my tractor). Normally, I have no problems unloading the usual lighter pallets, but with the much heavier pallets this time . . . well, I did.

(An example of this shipping scrap metal overseas. The container is at max weight (grossed out) with about two feet of scrap metal, above that is only air. If you filled the container to the top, it couldn't be lifted.)

Further, the ocean freight people, the trucking company, the rail connection, UPS, the ultimate consignee, and UPS/FedEx were NOT kind to the pottery. Something like 60% of the items were broken in transit (know anyone who needs a PILE of busted pottery shards?) so he's going back to the much less fragile fabric and wood items for the next shipments.

He also told his packers to put the heavier boxes (with the pottery) on the bottom of each pallet, evidently they didn't listen and some of the pallets were very top-heavy and toppled over when customs opened the container for inspection. They weren't happy either, and just shoved everything back into the box and closed the doors.

(The railroad also took three weeks to move the container 210 miles from Savannah (port of entry) to Jacksonville, which calculates to four tenths of a mile per hour, and then lost it in the rail yard for another two weeks. But that's a different tale of woe . . . )

Best Regards,

Mike/Florida

 

[GeneV]

This is incorrect. Increasing engine RPMs increases speed of FEL movement in feet-per-second but does not increase lift capacity in pounds.

It shouldn't, but yet it does, at least on mine. Most noticeable on the backhoe, lifting up a big log with the thumb.

 

[KWentling]

It shouldn't, but yet it does, at least on mine. Most noticeable on the backhoe, lifting up a big log with the thumb.

That is my experience too with my BX22. At idle I get no movement with either the loader or backhoe. I believe the newer than my BXs were much better in that regard.