Torque vs PSI vs GPM

[woodlandfarms]

I have a hydraulic post hole digger. I was watching a how to video with a skid steer and the operator suggested running at idle for the best results.

Began to think about this and wanted to get smarter on Hydraulic theory.

In a hydraulic system, PSI is a contant for the most part (?). GPM is variable to the speed of the pump (?). So do I have basically the same torque at a low GPM and a high GPM?

So when drilling a hole, my system is no stronger at a higher RPM than a lower RPM? Or the difference in between low and high GPM insignificant? GPM is just an equation for speed in Hydrualics, not force?

And finally, looking for a response in Laymens terms. I realize that while I did college level math, I have forgotten all of it when helping my 10 year old nephew with basic fractions.


Carl

 

[J_J]

I have a hydraulic post hole digger. I was watching a how to video with a skid steer and the operator suggested running at idle for the best results.

Began to think about this and wanted to get smarter on Hydraulic theory.

In a hydraulic system, PSI is a contant for the most part (?). GPM is variable to the speed of the pump (?). So do I have basically the same torque at a low GPM and a high GPM?

So when drilling a hole, my system is no stronger at a higher RPM than a lower RPM? Or the difference in between low and high GPM insignificant? GPM is just an equation for speed in Hydrualics, not force?

And finally, looking for a response in Laymens terms. I realize that while I did college level math, I have forgotten all of it when helping my 10 year old nephew with basic fractions.


Carl

Torque should be about the same if the pressure is constant.

Torque is based on displacement in cuin, and pressure.

Rpm is based on the pump flow and cuin..

Pressure is based on the resistance the motor has to overcome. The load.

To check out some figures, go to

Surplus Center - Tech Help

Go to calculators, then select motor speed and torque, and plug in some figures.

Actually, psi is not there until you encounter some resistance, so pressure is not constant. If you have the same load the pressure is constant