Hydraulic Pump, no load power use

[cmaas]

I am fitting a 3 cu. in. pump to a custom vehicle. The pump is used intermittently and is powered by the vehicle's motor. Rather than disengage it using an electric clutch I am wondering if I can just leave it engaged full time. Can anyone tell me approximately how much torque it takes to spin a 3cu. in. 30gpm pump when it's not under load?

 

[oldnslo]

Many years ago I was working for a gear pump manufacturer and they dd not publish any data but a pump producing 28 GPM at 1750 RPM required approximately 3 HP just to circulate that flow at 30 PSI. I do not know how much the HP requirement would vary with a smaller displacement at a higher RPM.

 

[cmaas]

Many years ago I was working for a gear pump manufacturer and they dd not publish any data but a pump producing 28 GPM at 1750 RPM required approximately 3 HP just to circulate that flow at 30 PSI. I do not know how much the HP requirement would vary with a smaller displacement at a higher RPM.

Thanks. I think I will try without the clutch but make provision for it to be installed later.

 

[SPYDERLK]

Good idea - especially if the pump is being run fast a lot of the time w/o using its considerable output. > If it spins slowly due to low engine speed most of the time you use the vehicle it wouldnt be so attractive to clutch it to save the lower parasitic power use.