Is hydraulic pump flow a linear function of RPM?

[SolarAndWood]

I have a pump my father in law thinks came out of a bulldozer. If I run it off the 540 PTO on my tractor, do I just get what ever fraction 540 is of its design speed in flow? Or, is there more to it than that?

Also, any idea what it is? I can't find any markings on it and my FIL doesn't remember what machine he pulled it out of 30 years ago.

 

[Jags]

In a perfect world, yes. Being a positive displacement pump, it is directly proportional to speed. Of course, internal wear, seals etc. can make it a "non" perfect world.

 

[DaveBP]

It's also likely to be a single-stage pump. Most splitter pumps these days are two-stage. When the going gets tough, they slow their speed to increase splitting force. A single-stage pump will need a much larger engine to drive it to top pressure than a two-stage pump of the same strength. But it will go faster at that higher pressure than the typical splitter.

But then, in a perfect world your Smuttynose IPA would never be laying around empty on the floor. Cy and Paul rule are my favorites. Support your local brewery!

 

[LLigetfa]

Looking at the size of fittings on both sides of that, I'm guessing that is designed as a motor, not a pump.

 

[Jags]

Looking at the size of fittings on both sides of that, I'm guessing that is designed as a motor, not a pump.

Hmmm. Could be. Its hard to tell What the fitting sizes are.

 

[SolarAndWood]

But then, in a perfect world your Smuttynose IPA would never be laying around empty on the floor. Cy and Paul rule are my favorites. Support your local brewery!

The Smuttynose is for display and size reference purposes only. I can assure you it was put to good use. I support my local guys but definitely have to support the regional guys that produce a product like that. My wife has been trying to convince me to go up to your neighborhood so that she can run the half marathon they are sponsoring.

 

[SolarAndWood]

Forgive my ignorance, what is the difference between pump and motor? The fittings are 1 1/4" OD and the pump housing is 6" across.

 

[Jags]

Forgive my ignorance, what is the difference between pump and motor? The fittings are 1 1/4" OD and the pump housing is 6" across.

A pump creates pressure. A motor takes pressure and makes work. (think generator vs electric motor.)

 

[SolarAndWood]

It's also likely to be a single-stage pump. Most splitter pumps these days are two-stage. When the going gets tough, they slow their speed to increase splitting force. A single-stage pump will need a much larger engine to drive it to top pressure than a two-stage pump of the same strength. But it will go faster at that higher pressure than the typical splitter.

My old diesel tractor is 29hp at the PTO...so have been looking for a pump that will produce the flow while running at idle. Right now, I am tapped into the loader line with my vertical splitter and have to run it in the high 2000s to get it to move even reasonably fast.

My father in law built a splitter on an 8-inch Ibeam with a big thick flange on it. He powered it with a 4 cylinder Wisconsin out of an old Bobcat. My plan is to sell the Wisconsin and repower it with either electric or a PTO powered pump. Then put a 6+ way wedge on it.

 

[SolarAndWood]

Forgive my ignorance, what is the difference between pump and motor? The fittings are 1 1/4" OD and the pump housing is 6" across.

A pump creates pressure. A motor takes pressure and makes work. (think generator vs electric motor.)

Got it...any idea how I figure out what this is? Does it being designed as a motor make is a show-stopper?

 

[Jags]

Forgive my ignorance, what is the difference between pump and motor? The fittings are 1 1/4" OD and the pump housing is 6" across.

A pump creates pressure. A motor takes pressure and makes work. (think generator vs electric motor.)

Got it...any idea how I figure out what this is? Does it being designed as a motor make is a show-stopper?

A hydraulic motor makes a crappy pump. It can be hard to tell which version it is in many cases. Most pumps will have a larger intake diameter than the output. Most motors have the same input/output diameter. This is NOT 100% true, just mostly true. ;-)

 

[SolarAndWood]

They are both 1 1/4". He said that when he had it hooked up to the wisconsin, the splitter was scary fast and he went to the smaller pump that is now on it. Does that help with the mystery or would that big of an engine make a motor work that way?

 

[Jags]

or would that big of an engine make a motor work that way?

Yes, it actually can. A motor WILL pump if turned. They are typically just not as efficient as a pump. (and different designs come into play as well)

Hmmm....you say "no info" is on the unit?? What the heck, if it worked before...who cares. Give it a shot. Depending on the old Wisconsin motor that was used, you probably have just as much HP at the PTO, just not the RPM. That may tame the "scary" part of it for ya. I would try it.

 

[LLigetfa]

Pumps generally have a larger intake to help fight cavitation. At those low RPMs, that shouldn't be an issue.

 

[Gooserider]

Do you have a local hydraulic shop and / or heavy equipment dealer? If you dragged it down to one of those, they might be able to ID it on sight, or at least give you a better idea of what it is....

It is also possible that there might be markings etc. buried under what looks like those multiple layers of paint...

Gooserider

 

[SolarAndWood]

Thanks guys. Once I get the Wisconsin sold off the splitter, I'll try both the 6hp electric with the current pump and then mate this up to the PTO and see what happens.