Bucket Test

[NCMau]

I am installing a PTO pump to my Old Iron. I bought this pump used few years back but I never checked it out. Yesterday I hooked it up for a bucket test just to see if it pumps. It does that. It pumped almost 2.5 gal in 15 sec. which equates to 10 gpm.
According to the Prince website, the pump supposed to be 7.2 gpm. I am assuming that because of no restrictions is pumping more than 7.2 gpm.
Can I assume this?

 

[J_J]

At what rpm?

Volume is determine by rpm.

At 540, it is supposed to pump 7.1 GPM

http://www.surpluscenter.com/item.asp?item=9-1047-7&catname=hydraulic

 

[NCMau]

At what rpm?

Volume is determine by rpm.

At 540, it is supposed to pump 7.1 GPM

Surplus Center - 3.6 CU IN PRINCE HC-PTO-7A PTO PUMP 540 RPM

It is the same pump.The tractor was running about 1000 rpm. My question was if there are no restrictions (just in and out from 2 buckets) the gpm should somewhat more than the rated specs... or not?
The reason I am asking is because I will be using an 8 gal tank which is barely enough for my pump.

 

[J_J]

It is the same pump.The tractor was running about 1000 rpm. My question was if there are no restrictions (just in and out from 2 buckets) the gpm should somewhat more than the rated specs... or not?
The reason I am asking is because I will be using an 8 gal tank which is barely enough for my pump.

Just run the engine at an rpm that will only produce 500 rpm on the PTO shaft.

That tank should be good enough.

Your GPM's will vary based on your tractor rpm's.

Hyd volume from pump represents speed of operation in most cases.

 

[lwalsh]

As JJ said if the rpm stays the same the flow will be the same. Doesn't matter if its free flow into a bucket or under pressure.

Like if a geared tractor is running at 2500 rpm it will travel the same speed in a given gear regardless how much weight you pull until you run out of power.

 

[TraderMark]

if the rpm stays the same the flow will be the same. Doesn't matter if its free flow into a bucket or under pressure.

Not always true....

Pump flows are rated at a certain rpm and at a certain pressure.
That pump is rated at 7.1 gpm @ 2000psi and 540 RPM.
Increase the speed or decrease the pressure and the flow goes up.
Decrease the speed or increase the pressure and the flow goes down.
Notice that this pump is rated @ 2250 psi MAX. It won't put out 7.1 gpm at that pressure though.

A hydraulic pump is not 100% efficient, meaning that not every drop of oil going in the inlet makes it out the outlet. Even new pumps have some internal bypassing. A pump rated for 7.1 gpm @ 2000psi may pump more than that if the pressure is less that what it's rated for.

As the pump wears its efficiency decreases, more oil bypasses internally and doesn't get pumped out the outlet port.

I've replaced numerous hydraulic pumps that would pump rated pressure, but when hooked to a flow meter had almost 0 flow at the rated pressure.

 

[J_J]

8.5 GPM at 540 displacement of 3.6 cu in.

It may be 7.2 GPM @ 540 rpm, @ 2250 psi

 

[NCMau]

Okay, thanks for the info. I'll be back in a week or so for more questions when I'll be ready for a dynamic test. I hope this pump is good.