KX91-3 - Auxiliary flow rate low compared to overall capacity?

[rmcrae]

I'm looking for a machine to power a drive head, so I'm concerned with flow rate. As I'm comparing specs of what's available locally, I notice flow rates for the Kubota seem a little strange. Specs say overall capacity is 27.3 gpm and list the auxiliary flow at 10.9. On the other machines I'm looking at, the auxiliary flow rate is usually a lot closer to the overall capacity. The 303C CR, for example, says overall is 23.1 with primary aux 15.85 and secondary at 7.15. Even the seemingly low flow 27D, with it's overall of only 16.4 gpm has an auxiliary rate listed at 13.9.

Is it just the way different companies list their specs? Like maybe the Cat and Deere can't really operate like that and the numbers are just theoretical?

I can get a good deal on the Kubota, but the 10.9 gpm is just a little too low. Is it possible to harness some of that remaining power to improve the flow to my drive head?

 

[lantraxco]

That's not right, the KX91-3 doesn't have the horsepower to push that kind of flow. I'm guessing the 27.3 is how much hyd oil the system holds, not flow. The Kubota brochure shows two pumps at 5.5 GPM, with a combined flow of 10.9 so your aux circuit is getting everything available. If you want more you need a bigger machine. The CAT spec for total flow adds in the gear pump for what, blade and boom swing maybe? Kubota is only giving you the two main pump flows in their number.

Pressure is torque, flow is speed, looks to me like you can run 3,500 psi at least, so what's the requirement on the drive head and can you go with a smaller motor at higher pressure, amounts to the same thing?

 

[rmcrae]

The brochure I'm looking at says 10.9 variable X 2, 5.5 gear X 1. Regardless, i'm not going to get more than 10.9 for auxiliary right?

I'll look into a smaller motor with higher pressure. The standard motor in the drive head is rated for 2500 psi.

 

[lantraxco]

My bad, you are correct! Apparently I need to clean either my glasses or my brain.

That is odd, you would think they would be able to combine flow to give you more on the aux circuit as you suggested.

 

[rmcrae]

That is odd, you would think they would be able to combine flow to give you more on the aux circuit as you suggested.

Might be able to. I Just found an ad for a used KX91 that says its plumbed for "high flow or pressure." It's from a rental place and the guy on the phone didn't know much. Trying to get a hold of whoever worked on it.

 

[DK88]

The brochure I'm looking at says 10.9 variable X 2, 5.5 gear X 1. Regardless, i'm not going to get more than 10.9 for auxiliary right?

I'll look into a smaller motor with higher pressure. The standard motor in the drive head is rated for 2500 psi.

Total flow is the 2 pumps PLUS! The pilot pump so those numbers add up.
If the aux flow is 10.9 gpm that means it doesn't or isn't built with a merge / divide valve to combine pump flows.

 

[rmcrae]

isn't built with a merge / divide valve to combine pump flows.

But you can add one right? I'm hoping that's the case with the one I saw in the ad.

 

[DK88]

Do they show 2 different specs for a std vs high flow model?