The return line IS the suction line. I said KW was correct on that fact. What contradiction? From the tank you’ve got gravity feed only with the pump off., When the pump is on you’ve got both gravity and suction. No contradiction.
No PTO pump pressure
- Thread starter CMR
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Thanks oldnslo, I always make sure there’s oil in the tank when I run the pump. Sometimes I even remember to open the ball valve. But the pump can run a few minutes with just the oil that’s in it. It’s only going about 500 rpm.
The filter is letting enough fluid through to run the 25 gpm valve and the bucket; it’s from Napa. It’s a spin on hydraulic fluid filter. If it goes bad I’ll probably just have to replace the oil, flush the lines. I doubt any damage to the pump or valve would result. If anybody has experienced such a problem I dare say it’s likely because they didn’t get the correct type filter.
LD1
Epic Contributor
Return and suction are two different things. Hence the contradiction
Hypothetical IF......If the ONE line worked as both suction AND return....what would be the point of a filter. Suction flows one way, return the other. Anything filtered out sucking would be blown back out returning.
I "assume" your system has a a line going from tank to PTO pump. THAT is the suction line.
Then a line going from the pump to the loader control valve. THAT is the pressure line.
Then a line going from the loader valve back to the tank THAT is the return line.....AND where most systems filter at.
You also said if the suction filter starves the pump then it wont hurt a thing.....you are mistaken. You run a hydraulic pump dry it wont last long at all.
My question still the same....is it working and did you get it figured out?
Yes it is working great. As I said, I cracked the pressure port on the pump which is the outlet port. Which purged the air from the pump which let fluid into the pump which primed the pump.
Your assumption on what constitutes a return line are close but not quite what my setup is. The valve return on mine T’s into my suction line, it doesn’t go to the tank because there’s only one outlet port on the bottom of the tank. So since most of the returned fluid goes back to the pump, I am safe in saying that my suction and return line is the same. But I do agree that the return line from the valve is usually referred to as The return. But both the valve and the pump have returns. One is suction the other gravity and on mine they both go in the same direction.
In any case I do not understand why you say the suction line from the tank and the return line out of the bottom of the valve go in opposite directions when they T together on their way to my pump. In my setup you could say just as well, that the valve return line is getting suction from the pump just as the tank line is. My filter is after the valve returns to the suction line so it IS filtering the valve return fluid AND the tank fluid BOTH. Because they do NOT go in opposite directions. It works great. When I started this thread I thought I asked if the pump sucked but found out from trial and error that it did.
It doesn’t take much oil to keep those pumps going but sure, if you run them dry they go bad, but they sure don’t need constant flow.
LD1
Epic Contributor
You are not doing a very good job describing the system.....which is adding to the confusion. Maybe it would warrant a picture.
In your case.....the piping UP TO the tee where the return comes in would simply be considered an extension of the tank. From that TEE to the pump is the suction line. From the TEE back to the valve would be the return.
Simple question, is the filter between the tank and the TEE (if yes it is wrong and you cam move fluid BOTH ways across the filter).
OR, is the filter between the pump and TEE. (that would be on the suction line....and not ideal but not bad).
Ideally, the filter would be on the return line....between the valve and the tank(tee).
Suction and return are NOT the same.
In your case.....the piping UP TO the tee where the return comes in would simply be considered an extension of the tank. From that TEE to the pump is the suction line. From the TEE back to the valve would be the return.
Simple question, is the filter between the tank and the TEE (if yes it is wrong and you cam move fluid BOTH ways across the filter).
OR, is the filter between the pump and TEE. (that would be on the suction line....and not ideal but not bad).
Ideally, the filter would be on the return line....between the valve and the tank(tee).
Suction and return are NOT the same.
oldnslo
Super Member
CMR
What you are attempting to describe sounds like it could be a semi closed loop system where oil returning from the valve tank port is directed into the pump inlet. While extending you are using oil from rod end and drawing oil out of the reservoir to feed the pump. When retracting the cylinder you are using oil from cap end of cylinder to feed pump and excess oil is returned to the reservoir.
Is this the system that you have?
What you are attempting to describe sounds like it could be a semi closed loop system where oil returning from the valve tank port is directed into the pump inlet. While extending you are using oil from rod end and drawing oil out of the reservoir to feed the pump. When retracting the cylinder you are using oil from cap end of cylinder to feed pump and excess oil is returned to the reservoir.
Is this the system that you have?
I don’t know what you mean by valve tank. The four cylinders have four pipes going to the valve body, and there’s a constant flow from the upper inlet of the valve body to the bottom of the valve body where it leaves to go to the T in the suction hose. The suction hose pulls from both the valve body and the reservoir (tank)
LD1
Epic Contributor
Where is the filter at? Between the tank and the TEE? Or between the TEE and the pump?
I said: “ my filter is after ( meaning downstream) the valve returns to the suction line so it is filtering the valve return fluid AND the tank fluid”.
I totally agree that suction and return are two different things. And as I said, I agree that the fluid out of the valve is return fluid. But in my setup, with the valve return fluid combining with the suction line at the T, there’s a suction line that’s got return fluid from the valve in it, which RETURNS to the pump. I think it’s purely logical to say that from the T to the pump the line is both suction line and return line. No contradiction, just a combining if two different lines
