No PTO pump pressure

[CMR]

I get the 90% estimate by virtue of the fact that the return from the valve is entering the T while the pump is sucking on the T, so why would return fluid instead go into the bottom of the tank. It’s primarily circulating in a pump to valve circuit. Which includes the

Filter

 

[wdchyd]

51551 wix micron rating - Google Search

it’s a 10 micron filter element, that’s pretty fine when used for a suction filter anywhere. Older Gear pump equipment usually uses filter elements of 25 micron.

 

[CMR]

Thank you, I saw that too. Well I’ll just keep an eye on it and if it doesn’t flow fast enough I’ll lose power but the pump won’t go dry. I’ll worry about it then. . It’s an old pump and I’ve got two spares. But I doubt it’ll get damaged before it shuts the loader down. I’ll get a 25 micron next year.

I like the filter between the pump and both the tank and the valve, on the suction. The old tractors just had screens on the tanks, so a 25 will be fine.

 

[LD1]

I don’t see how I could attempt to claim a pressurized supply line could pass as a suction line, you’re really grasping at straws there aren’t you? Let’s just say the only return is from the valve to the T then, and anything with suction is just suction line. That’s fine. So the filter is on a suction line. But you have to agree that the fact remains that some of the fluid, probably 90% of it, is not going to the tank, and IS being suctioned through the filter, right?

I dont know why you are still wanting to argue about this.

Its very clear you have little to no understanding of hydraulics. Not trying to be mean or throw insults.....just being honest.

So why are you continuing to want to argue with me about trying to HELP you understand.....

By YOUR logic.....90% of the oil coming out of the return line is entering the suction line....therefore you call the suction line a return line.....

Well 100% of the oil coming out of the pressure line is going into the return line.....so by YOUR flawed logic....that would make the return line a pressure line.

You seem to think that one of those makes sense and the other does not. Well they BOTH dont make sense.

Quit visualizing the line from the tank to the tee and the tee as lines. View them as part of the TANK....and it should all make more sense.

I may be wrong.....because "tone of voice" isnt depicted in written word.....but I sense a little attitude. All we are trying to do is help. The constant "like I said before" comments, or claiming that I am grasping at straws like....gives me the impression that you know more about hydraulics than those you are seeking help from.

 

[oldnslo]

Thank you, I saw that too. Well I’ll just keep an eye on it and if it doesn’t flow fast enough I’ll lose power but the pump won’t go dry. I’ll worry about it then. . It’s an old pump and I’ve got two spares. But I doubt it’ll get damaged before it shuts the loader down. I’ll get a 25 micron next year.

I like the filter between the pump and both the tank and the valve, on the suction. The old tractors just had screens on the tanks, so a 25 will be fine.

CMR
Your thinking is a little flawed in that losing flow won’t damage the pump. A starving pump is cavitation which will destroy the pump. Having spares is nice but where is the debris created by cavitation going? Answer is into the rest of your system.

 

[CMR]

I dont know why you are still wanting to argue about this.

Its very clear you have little to no understanding of hydraulics. Not trying to be mean or throw insults.....just being honest.

So why are you continuing to want to argue with me about trying to HELP you understand.....

By YOUR logic.....90% of the oil coming out of the return line is entering the suction line....therefore you call the suction line a return line.....

Well 100% of the oil coming out of the pressure line is going into the return line.....so by YOUR flawed logic....that would make the return line a pressure line.

You seem to think that one of those makes sense and the other does not. Well they BOTH dont make sense.

Quit visualizing the line from the tank to the tee and the tee as lines. View them as part of the TANK....and it should all make more sense.

I repeat: I am not arguing the terminology. I’ll call those pipes whatever you want to call them. Im more interested in your initial assertion that the location of the filter was wrong. Now, we agree that 90% of the fluid coming down the return line goes to the filter then the pump. Which I say is a good setup. So tell me how it’s wrong, and what you think
As to your insult that I know nothing about hydraulics, I might not know as much as you, but who found the problem? Yours truly figured out it was an air lock problem. I cracked the output on the pump and got the air out. Now, let’s quit the personal attacks, nobody is perfect, and look at this objectively. I’m asking you what would you do to improve this setup. I’m not tapping into the tank for the return line. So I can put the filter between the valve and the T but I like filtering the tank outflow too so I don’t really see a perfect solution

 

[CMR]

CMR
Your thinking is a little flawed in that losing flow won’t damage the pump. A starving pump is cavitation which will destroy the pump. Having spares is nice but where is the debris created by cavitation going? Answer is into the rest of your system.

Yes into the rest of the system, IF it’s allowed to get that bad. So here’s my question to you. Let’s say you’re on the tractor loading manure or gravel. You’re busy with the controls. A hose bursts, you lose pressure, the controls no longer control anything, right? You’re out of commission. What do you do? Do you keep the engine and the OTO on? Hell no, you shut the thing off. Long before any damage occurs. Am I missing something? I can’t remember what started this conversation

 

[LouNY]

I think what he is trying to say and you are doing your best not to see;
is that restricted flow into the suction of a hydraulic pump will lead to cavitation in the pump from the low
pressure (actually a vacuum) at the inlet. This low pressure cavitation is more prone to occur with moisture
in a hydraulic system. You system will have moisture in it from the atmosphere even without a vented reservoir.
Which will also lead to a reduced suction pressure. That 15 micron filter on the suction if it does not have a
vacuum bypass will be extremely restrictive with cold oil. You are setting up a perfect situation for pump
suction cavitation which will erode minute pieces of steel or aluminum from your pump.

 

[CMR]

looks like I put my reply into the quote above, sorry about that. I’m still learning this forum stuff. My reply starts with “ I repeat, I’m not arguing the terminology.
Whatever you say the name of a line is that’s what it is. So where do you think I should put the filter? You said it belonged in the return line coming from the valve. If I do that it’s no longer filtering what little comes out of the reservoir. Not gonna tap the reservoir, the T stays. I appreciate your help. But don’t tell me I know next to nothing about hydraulics when it was me who found the problem. (Air lock)

 

[CMR]

I think what he is trying to say and you are doing your best not to see;
is that restricted flow into the suction of a hydraulic pump will lead to cavitation in the pump from the low
pressure (actually a vacuum) at the inlet. This low pressure cavitation is more prone to occur with moisture
in a hydraulic system. You system will have moisture in it from the atmosphere even without a vented reservoir.
Which will also lead to a reduced suction pressure. That 15 micron filter on the suction if it does not have a
vacuum bypass will be extremely restrictive with cold oil. You are setting up a perfect situation for pump
suction cavitation which will erode minute pieces of steel or aluminum from your pump.

I appreciate seeing that information, which is the first time I have seen it. You said “if it has vacuum bypsss”. If what has vacuum bypass? Not much moisture here in Montana, especially this year, but I’ve been running this loader 30 years now and it’s still hot the original pump. I only replaced the valve because the bucket tilt wasn’t holding down. And I think that was due to a stuck check valve but that’s just my guess. I figured some seal dried out somewhere from being in the sun 30 years. I’ve never heard of or seen cavitation before.