BIGGER loader cylinders.

[Reg]

Yes, clearly the overhead of lifting the loader's arms is already in the base case and any percentage increase in force at the cylinder returns a greater percentage increase in PAYLOAD.

Not as much as one might think, since although the loader (with 67 inch bucket) has a spec weight of 1320 lbs very little of that is actually lifted.
MOST of the loader's weight is in the frame, not the arms.

PART of the reason that I bought a narrow grapple was to save overhead weight, i.e. every additional pound of grapple weight is a pound less of payload.

For brush a wide grapple is probably better, it can grab more and the load is less dense, for logs it is important to center the load as much as possible anyway and that is as easy with a narrow grapple as with a wide one - plus the benefit of the higher payload.

 

[LD1]

Actually, it takes more than you would think to lift just the empty loader. Them buckets are heavy, and dangling way out in front of the cylinders so they have alot of leverage.

On both my old L3400 and my new mx5100, it takes about 600 psi just to lift it empty.

So thinking in terms of 2400psi spec for operating pressure, it takes 25% just to lift empty. Or in other words, you only have about 75% of the cylinders power to be used for lifting whatever you put in the bucket.

 

[Reg]

The end run around figuring all the geometry would be to put a pressure gauge in a lift cylinder and read it when it just gets off the ground - I guess that would also be the pressure to hold it too.
Hmmm, that may be a good way to actually WEIGH logs - - ...probably not.

In real world terms I'll just turn up the relief pressure and (subjectively) see how much bigger tree trunks I can lift.
If that doesn't impress me (again, a subjective measure) I'll start spec'ing out fatter cylinders

None of this before I get a gauge to at least measure the current relief pressure.
I want to be able to reverse this with some accuracy, just in case some other problem crops up.
"Set to spec" can be a useful troubleshooting technique.

 

[LincTex]

I'd be worried about the hydraulic pump & drive gears.

Two Examples:
1) The Farmall M, Super M must use the distributor gear from a 400/450 when going with a "live" pump (goes between distributor and accssy case). The hydraulic pump adds that much load.

2) My 1980 John Deere 850 (Yanmar) sheared a pump shaft key, doing loader work. It spalled the shaft pretty bad. When I had the pump off to change the key, I noticed the steel gears were carving a "new" travel path into the aluminum housing.... VERY bad.

I'm Jus' Sayin' - - be cautious!!!
No one ever "gains" anything for free.

 

[art]

I don't get into this to often but have you looked at the load capacity of the front end? You might want to look at that first although a little bump on pressure might be all you can handle. I have seen tractors with to big of loaders and lifting to full capacity breaking the front axles.

 

[Turbys_1700]

Most all manufacturers set the relief a little below the max. I would adjust the relief first as many here have suggested. I would also as art suggest double check the capacity of your front axle. Factory specifications typically allow users to maximize pressure and still stay under their front axle capacity if using factory loaders. Ensure that any modifications to increase lift capacity were within the specifications of the front axle to carry the load.

 

[SPYDERLK]

Actually, it takes more than you would think to lift just the empty loader. Them buckets are heavy, and dangling way out in front of the cylinders so they have alot of leverage.

On both my old L3400 and my new mx5100, it takes about 600 psi just to lift it empty.

So thinking in terms of 2400psi spec for operating pressure, it takes 25% just to lift empty. Or in other words, you only have about 75% of the cylinders power to be used for lifting whatever you put in the bucket.

Other real life corroborating data:

I have had the opportunity to do measurements at points on a boompole using a Dillon force gage. I used the 7520 as the test platform and turned hyd pressure down to 1000PSI so I wouldnt bend the boompole. I did 2 setups:
1]

Used a chain in place of the toplink to get the lift ratio as close to 1 as possible. Best I could do was 3/4 - - 24" lift at the eyes and 32" at the end loop of pole 108" out from the eyes.​

2]

Used the toplink adjusted to max length. The best lift ratio I could get at the pole end was 0.61​

The lift forces I measured in the 1st case were 1710# at the eyes, 1160 @ 56", and 980 @ 108".

The lift forces in the second case were 1700, 1200, 880 respectively.

,,,I believe the anomalies shown are due to my neglect in assuring that the lift was always done at the same eye height. The force available at the eyes varies some with height.

I did one more experiment in case 2 by successively shortening the toplink 3 turns at a time. Here I did take care to hold eye height pretty close to constant. The force measurements at 108"were 880, 850, 800, 760, 725.

While I had the force gage I took some loader measurements too. I found that it took 700PSI to get the loader to rise with the Tilt-tatch and bucket -- and 800PSI to get it to full height. I then turned the pressure up to 3000 as I normally keep it set. Center bucket force was 5100# at 1 foot lift height. ... Quite a surprise since this is 26" forward of the pins.​

 

[Sawyer Rob]

I say "do it", I'm betting your dealer has some front end parts he'd like to sell you! lol

SR

 

[EddieWalker]

I learned my lesson years ago with trying to out think the engineers who design vehicles and machinery. They do it for a living. They do all the research and factor in all the component. Sometimes the get it wrong, but overall, they know a lot more then I ever will. If it was just a matter of putting on bigger cylinders, that would be pretty simple for them to do at the factory. Then they would sell more units because of the greater lift ability compared to the competition. My guess is that the loader came with the very largest cylinders that they calculated the tractor could handle when considering the pump, the pins, the metal used to build the loader arms, the frame of the tractor and the strength of the axle supporting the weight. It's the same when figuring out the size of the bucket. Just putting a bigger bucket on the loader does not mean your tractor can handle it.

If it's really such a concern as to consider rebuilding or home engineering modifications to it, in my opinion, you would be better off for the long term selling what you have a getting something bigger.