how many GPM is needed

[DaBear3428]

I lust for power, the more the better. My limit is my wallet.

honest answer lol

 

[Rod in Forfar]

Something also to think about is that your hydraulic pump, whatever its size, will exact a toll in fuel consumption in direct proportion to how much oil it moves at a given pressure. My HST Kubota B7510 uses more than twice the fuel of my Bolens G174 4WD manual when doing the same job. When running a 7.5 kw generator the difference is even more extreme, because the Bolens can loaf along in 2nd gear PTO and still run the house, but the Kubota can only rant along at 2500 rpm.

So the contrarian point of view asks how little hydraulic volume do you have to have for daily jobs with your tractor? My Bolens dumps its trailer and lifts implements just fine with 4 gal/minute, while the Kubota splits 8 g/m among power steering, the transmission, and auxiliary power to dump that same trailer. Mind you, with the pressure turned up to 2500 psi, it will dump a full load of gravel out of the trailer, a feat the other four tractors on my property, regardless of their size, cannot accomplish.

 

[Bentrim]

Many years ago the company I worked for took specifications for a bid for a tractor loader backhoe. The township that wanted to purchase the hoe picked the one they wanted and wrote the specifications for that unit into the bid. Without them allowing for differences in the specifications only one brand dealer could submit bids. When I saw the bid they had specified such trivial things and you would have thought they were experts at designing a tlb.
Why do I bring all this up? Manufacturers build tractors to meet certain requirements yet keep efficiency and cost down. Most manufacturers equip tractor to handle most tasks the tractor is required to do. Some may even offer a larger pump. Most tractors are equipped with pumps large enough to operate a loader at a reasonable speed. Some manufacturers offer different size cylinders on the loader depending on the pump size on the tractor. Even others use a separate pump for the loader.
My thoughts are don't reengineer the tractor. Figure out what you want to do with the tractor and purchase one that meets your requirements. The tractor and any attachments should be engineered to work together, it is when you add third party or specialized equipment your requirements may be different.

 

[5030]

Both my M9's have 2 pumps mated together. One pump for the hydrostatic steering the other larger Pump for the hydraulics. Not sure what the GPM rating is but I've never ran out of hydraulic power.

 

[Cycledude]

Extra hydraulic capacity in my opinion is usually a good thing, yes it will consume a little more fuel but when your short of hydraulic capacity it gets pretty expensive to resolve that issue.

 

[sd455dan]

You make it sound as if there is a real world difference between 8.8gpm and 9.1gpm. so much so that it should be a key factor in picking a tractor brand.

If you need more flow.....get s bigger tractor....get a pto driven implement....or get a pto pump.

With so little difference in GPM among similar sized machines.....it's not even on my radar when comparing tractors.

And if you need 20gpm.....a 50hp tractor with a 20gpm PTO pump is alot cheaper than a 100hp tractor

That similar sized pump total output does seem to be the norm on new under 60 HP machines,

but as an example on older tractors, my 1967 Ford 3000 tractor ~40 HP
had a 16+ GPM crank driven pump (FEL) a 5 GPM power steering pump, a ~5 GPM rockshaft 3point pump and an SOS trans pump only 40 HP and about 26 GPM total not counting the select o speed transmissions pump.
My 55hp rhino tractor has 11 GPM for FEL/ PB remotes, 5 GPM pump for steering , and a scotch yoke 5 GPM pump for the 3 point so 21 GPM total.
I am a fan of individual pumps for function. With them no loss of loader function when steering is worked hard or loss of 3 point either. Seems like all of the under 60HP new tractors have maybe 2 pumps. Jmo, I don't think that is an improvement other than maybe ease of service.

Same for removing FEL bracing to the front and rear axle mounting points... engine access is easier and making a prettier tractor, But not as strong when pushing FEL capabilities.

For the OP yeah why not add a PTO pump if he wants /needs it.

 

[LD1]

That similar sized pump total output does seem to be the norm on new under 60 HP machines,

but as an example on older tractors, my 1967 Ford 3000 tractor ~40 HP
had a 16+ GPM crank driven pump (FEL) a 5 GPM power steering pump, a ~5 GPM rockshaft 3point pump and an SOS trans pump only 40 HP and about 26 GPM total not counting the select o speed transmissions pump.
My 55hp rhino tractor has 11 GPM for FEL/ PB remotes, 5 GPM pump for steering , and a scotch yoke 5 GPM pump for the 3 point so 21 GPM total.
I am a fan of individual pumps for function. With them no loss of loader function when steering is worked hard or loss of 3 point either. Seems like all of the under 60HP new tractors have maybe 2 pumps. Jmo, I don't think that is an improvement other than maybe ease of service.

Same for removing FEL bracing to the front and rear axle mounting points... engine access is easier and making a prettier tractor, But not as strong when pushing FEL capabilities.

For the OP yeah why not add a PTO pump if he wants /needs it.

I am speaking in terms of late model tractors. Things made in the last two decades. Not 1960's and 1970's machines.

Alot of older machines ran alot higher GPM, but at a lower pressure. And to compensate they used alot larger cylinders (or alot longer stroke and had geometry to maximize lift capacity at lower PSI)

Trying to compare a 1970's machine and crank mounted loader pump to a modern tractor of similar HP is apples to oranges comparison.

Speaking of late model 40-50HP machines, like deere 4-series, kubota MX or GrandL series, or similar machines from any make.....you will find real similar specs for available implement flow and pressure. Usually between 8 and 10gpm

 

[Gord Baker]

Decide what you need to run, find out the GPM and PSI required. You will likely only use one at a time.
The 'rule of my thumb' is go big so you can easlily operate a Splitter, mower etc.

 

[sd455dan]

I am speaking in terms of late model tractors. Things made in the last two decades. Not 1960's and 1970's machines.

Alot of older machines ran alot higher GPM, but at a lower pressure. And to compensate they used alot larger cylinders (or alot longer stroke and had geometry to maximize lift capacity at lower PSI)

Trying to compare a 1970's machine and crank mounted loader pump to a modern tractor of similar HP is apples to oranges comparison.

Speaking of late model 40-50HP machines, like deere 4-series, kubota MX or GrandL series, or similar machines from any make.....you will find real similar specs for available implement flow and pressure. Usually between 8 and 10gpm

No argument, I agree more the same than different.

Given a choice though, not sure the new machines with 2 pumps or less is superior or a real "advancement". if I buy a new tractor if given a choice between a single pump for everything, or a tractor with a steering pump, FEL pump and separate 3 point pump... all else being equal I would chose the tractor the multiple pump design.

Looking at some new machines,
The 2850M Massey has a bit better hydraulic flow specs than the average ~36 PTO HP CUT with 7.0 gallons for steering and 12.6 for FEL /implements. so 19.6 GPM total.

 

[Smokeydog]

My Kubota M59 TLB has 16gpm. Like the large and quick aloader for that size machine. Two pumps for the backhoe helps moving large cylinders.
Do use a hydraulic pole chainsaw motor.
While it might run some hydraulic mowers I think it is not really set up to handle the heat load of continuous operations. Tractors built for hydraulic mowing have added front and/or pto pumps, tanks and coolers.
Large Hydraulic motors usually require an always open path back to tank to allow hydraulic motors to coast to a stop and a case drain like on skidsteers.

Usually a significant step up in cost to get high flow in tractors.