Constant Pumping - Questions about Operation

[TractorFella]

Hi All,

I feel a bit dumb for asking these questions, but my owner's manual isn't helping me much, and this is my first tractor so I am learning a lot (2005 MF 461).
So, Constant Pumping. Move the Position Control Lever up to Constant Pumping and the manual says it "delivers a constant flow at 16.7 l/min" and is "controlled by the Draft Control lever." So where does this 16.7 l/min flow to? I have 2 auxiliary hydraulic levers to the right of my driver's seat that control two sets of outlets at the rear. Does this mean Constant Pumping has to be active to allow flow to these hydraulic outlets? I briefly manipulated the auxiliary levers the other day without Constant Pumping active and it sounded like the engine became loaded, so I would think not. Also, "controlled by the Draft Control lever" <- does that mean once the Position Control Lever is in Constant Pumping the Draft Control Lever changes the overall flow volume? Like I said... lots to learn!

Thanks, and have a great weekend!

 

[CobyRupert]

"Does this mean Constant Pumping has to be active to allow flow to these hydraulic outlets?"
I don't know about MF, but if I had to guess, I say no.

"So where does this 16.7 l/min flow to?" To the attachment connected to the hydraulic outlets (SCV's).

Typically you use the hydraulic outlets to stroke a hydraulic cylinder on an attachment a foot or two in either direction. And when you not moving the lever there is no flow, and the cylinder doesn't move.
Whereas IMHO (I might be wrong, W.A.G. might be a better term) the term "constant pumping" sounds like an option if you are running an attachment with a hydraulic motor (or an attachment that has it's own valves, and relief, etc...) connected to the hydraulic outlets, where the hydraulic system of the attachment wants a constant (supply and return) flow.
Not sure how the draft control lever is involved, other than it changes it's function to something else when in this mode.

I may be all wrong, and someone can better explain M.F.'s, and open-center, or closed-center systems, etc... But good luck.

 

[TractorFella]

"Does this mean Constant Pumping has to be active to allow flow to these hydraulic outlets?"
I don't know about MF, but if I had to guess, I say no.

"So where does this 16.7 l/min flow to?" To the attachment connected to the hydraulic outlets (SCV's).

Typically you use the hydraulic outlets to stroke a hydraulic cylinder on an attachment a foot or two in either direction. And when you not moving the lever there is no flow, and the cylinder doesn't move.
Whereas IMHO (I might be wrong, W.A.G. might be a better term) the term "constant pumping" sounds like an option if you are running an attachment with a hydraulic motor (or an attachment that has it's own valves, and relief, etc...) connected to the hydraulic outlets, where the hydraulic system of the attachment wants a constant (supply and return) flow.
Not sure how the draft control lever is involved, other than it changes it's function to something else when in this mode.

I may be all wrong, and someone can better explain M.F.'s, and open-center, or closed-center systems, etc... But good luck.

Thanks for the info Cody. Appreciate the reply. Not running anything at the moment, so I'll have to do some experimentation in the future.

Have a good one!

 

[Birdhunter1]

I don't know how the 461 differs in the hydraulic system from a 1960's MF 135 but on the old 135 the constant pumping is what fed any hydraulic cylinders you might have hooked up and I believe the way it was setup you couldn't operate your 3 point arms independently from the aux hydraulic system.

On your tractor it could be setup differently, since you have aux hydraulic remotes it is possible they will work independently on the 3 point arms. Attach a cylinder and operate your remote levers and if it works I would forget about the 'constant pumping' setting. If you have an owners manual on it it will probably explain it somewhere.

 

[Bavarian]

Constant hydraulic flow means: your hydraulic pump delivers that volume at rated engine speed. Or any lower volume if RPMs are lower. But as soon as the engine is running, the pump delivers some oil.
Where does it go? The next term comes into the game: Open Center. That means, your hydraulic control valve(s) allow the provided oil to flow free back through the filter to the oil reservoir. If you move one or more levers, the oil doesn't flow back to the reservoir, it's diverted to your implement (cylinder). The oil coming back from the cylinder flows through the valve, through the filter, back to the reservoir.

 

[TractorFella]

Interesting stuff. Thanks Birdhunter1 and Bavarian. I was curious if I needed Constant Pumping to be active for the aux remotes to work. Sounds like it may be so. One of these days I will find out! Thanks again.

 

[Agvg]

Your tractor may have two pumps, one classic MF pump that runs the 3pt and one that feeds aux hydraulic.