front loader question

[4570Man]

Yes, but I don't think it's a linear relationship. 1200 to 1600rpm should make a larger gpm increase than going from 2200 to 2600rpm.

I agree. The loader or backhoe is drastically faster going from 1600 to 2200 rpm. The difference is very minor going from 2200 to 2700 rpm. The backhoe actually says optimal engine rpm is 2200 rpm to 2400 rpm even though the pto 540 is at 2700 rpm.

 

[Luke'sScreenName]

That and interesting point that I had not thought of. But I might postulate that resistance to flow is the more important factor. So for that same interval flow rate increase, resistance should have a greater impact at higher absolute rates (especially as viscosity increases and assuming fairly laminar flow). Not positive though.

 

[SPYDERLK]

Yes, but I don't think it's a linear relationship. 1200 to 1600rpm should make a larger gpm increase than going from 2200 to 2600rpm.

I agree. The loader or backhoe is drastically faster going from 1600 to 2200 rpm. The difference is very minor going from 2200 to 2700 rpm. The backhoe actually says optimal engine rpm is 2200 rpm to 2400 rpm even though the pto 540 is at 2700 rpm.

Not straightforwardly true however. It should be the same increase ideally, but -- All pumps have leakage as they pump. Leakage is a function of time and pressure. At the same load pressure but at a lower speed the leakage is greater in proportion to the volume pumped because each revolution takes longer.
... The reason you see a huge difference from 1600 to 2200 is that so much of pump volume goes into leakage at 1600. At 2200 that leakage is almost identical, but is much less in proportion to the increased volume pumped by the higher number of revolutions.

 

[SPYDERLK]

That and interesting point that I had not thought of. But I might postulate that resistance to flow is the more important factor. So for that same interval flow rate increase, resistance should have a greater impact at higher absolute rates (especially as viscosity increases and assuming fairly laminar flow). Not positive though.

Sorry, I deleted and re posted. ... I think you answered the post that is now immediately following yours.

 

[chris1006]

Had a break in the rain this morning and hooked the 4in1 bucket up. Played with it a while and found that holding the button depressed for about 1 to 2 seconds after hearing it clamp shut will prevent it from falling open when dumping. Can even see the hoses "tighten up". I had been releasing button as soon as I heard the CLAMP of it closing. I am sure others may be quicker but seems like it just takes a couple seconds to build to full pressure. Guess I just needed more time playing with it before I assumed something was wrong.

 

[chris1006]

Oh yea, thanks for all the responses.

 

[SPYDERLK]

Had a break in the rain this morning and hooked the 4in1 bucket up. Played with it a while and found that holding the button depressed for about 1 to 2 seconds after hearing it clamp shut will prevent it from falling open when dumping. Can even see the hoses "tighten up". I had been releasing button as soon as I heard the CLAMP of it closing. I am sure others may be quicker but seems like it just takes a couple seconds to build to full pressure. Guess I just needed more time playing with it before I assumed something was wrong.

Great! ... You have some air tho. Be sure you are topped with fluid and cycle all your cyls fully a few times at mid to high rpm, holding briefly against each extreme.

Should help.