Question re PTO driven hydraulic pump for hydraulic post hole digger

[davehowell]

Good folks, We have a Land Pride hydraulic post hole digger that specs a 5-13 gallon per minute hydraulic pump. Our B7800 is on the low side, a six gpm pump at 2000 psi. The auger stalls, ie, quits rotating,as it drill down through hard rocky soil. Would the post hole digger's performance be improved with a PTO hydraulic pump, separate oil reservoir, larger hydraulic lines and separate valve. Right now, we plug into the loader curl circuit for power. Thanks for any help. We bought it to put in fence posts.

 

[mikehaugen]

I don't think a pto pump is your best answer. 2000 psi should be enough (assuming you are actually producing that, your pump could be getting worn) a lower flow will just make the auger turn slower. All hydrualic motors have some internal leakage, an older worn pump will have more leakage. If you are using the curl function, it is probably pretty restricted and you may not be providing enough flow to overcome that leakage under load. Is there a power beyond port somewhere that you could add a valve?

I think either the auger motor is either worn out, or you should provide more flow by tapping into the hydraulics somewhere else on the tractor. A pto pump may mask that problem, but the cost of a pump, plumbing, tank, and valve will probably put you over $1000 and add complexity. I would start with a gauge and put it right at the end of the line coming from the tractor that you are using, and if you are close to the 2000 psi then try a gauge with a tee inline with the auger attached and see what kind of pressure you have when the auger stalls. If it is a lot less than what you had before, then your auger motor is worn... if it is about the same (close to 2000), then you are just asking too much from the auger.

 

[J_J]

What mikehaugen said plus,

Most PTO units generate about 2250 psi, and if your hyd auger is perfect, you will gain a little torque.

Volume as in GPM's, only increase speed.

Your loader lines might be 1/4 in, so 3/8 or 1/2 in might help somewhat.

Install a 3000 psi hyd gage in a tee at the IN port of the loader valve and you will see any hyd pressure that is developed by any hyd component.

Check and or adjust your loader relief valve for correct pressure.

 

[davehowell]

Mike, Thanks for your notes, your thoughts are similar to mine.

I have the gauge, on a "t", but was unsure if the valve block/curl circuit was the best place to check pressure. The hydraulic lines are pretty small, "3/8"?, and the flow restriction of the quick connects do not help.

Interestly, the hydraulic lines do not get hot when using the hydraulic motor which may be a benefit of the lower flow pump.

I am thinking that I have hard rocky soil that would making any auger/digger ineffective.

Thanks again for your comments. I will do as you say. Dave

 

[davehowell]

J J,

Thanks for your note back. Your comments are very helpful. I believe that I read on this forum that I should have 2000 psi pressure at the pump and cannot find any figure in the Kubota information. Should I adjust/shim to get the 2000 psi at the quick connect output of the valve block, or is there a place closer to the pump where I should measure the pressure?

Thanks again for any help, Dave

 

[J_J]

I would recommend installing a gage and use it to monitor and trouble shoot the hyd system, but

You can plug in a gage at the QD wherever and flip the valve lever momentary and read the pressure.

If the relief valve is adjustable, then turn the screw in a little and flip the lever again and repeat until the relief pressure is at specs.

If the relief has shims, then you have to add shims until the pressure is met.

Your relief setting should be in your manual.

The shims come in packs with different thicknesses.

Engine should be off when adding shims.

 

[Leejohn]

The owner manual has psi at 1920 to 1992.