Hydraulic Filter Question

[unixkid]

I'm building a log splitter and am to the point of putting the hydraulic system together. My question is about the return line filter. All I see available from Surplus Center for return line filters are typical canister filters of varying sizes but they all pretty much say max 200 psi operation. How is it possible to put a 200 psi filter on a system that has all other components rated for 3000 psi ???? My novice approach is to put every component rated for the same max psi.

Please help.

The splitter will be : 25 gallon tank, 16 gpm pump, auto-cycle valve, 3/4 in lines, splitting cylinder, log lift valve, 3/8 in lines, log lift cylinder, return filter.

Thanks,
-unixkid

 

[murphy1244]

I'm building a log splitter and am to the point of putting the hydraulic system together. My question is about the return line filter. All I see available from Surplus Center for return line filters are typical canister filters of varying sizes but they all pretty much say max 200 psi operation. How is it possible to put a 200 psi filter on a system that has all other components rated for 3000 psi ???? My novice approach is to put every component rated for the same max psi.

Please help.

The splitter will be : 25 gallon tank, 16 gpm pump, auto-cycle valve, 3/4 in lines, splitting cylinder, log lift valve, 3/8 in lines, log lift cylinder, return filter.

Thanks,
-unixkid

Cause there is very little restriction on the return = low psi

 

[J_J]

The return or OUT port on the log splitter valve has very little restriction to the fluid so it just flows almost with no pressure. The hyd filter should go in the return flow path.

You could even put your hand in the return flow and not be hurt, except by heated fluid.

They do make inline high pressure filters capable of handling 3000 psi, but you do not need them in a log splitter hyd circuit.

 

[benitez]

i have a 30 ton north star log splitter and it has no filter. should i put 1 on ?

 

[J_J]

Yes sir, every hyd system should have a filter .

I am surprised that the manufacturer did not install a filter.

Did you buy it new?

I should ask does it have an engine driven pump, as a 3pt log splitter fluid would get filtered by the tractor hyd filter.

 

[benitez]

im sorry its not a 3pt log splitter and yes i bought it new last year from north star

 

[unixkid]

Thank you for the replies. I understand now.

-unixkid

 

[ilander]

If I may put my two cents worth in, hydraulic filters need not be on the return line. They can be on the suction line before the pump. I have three tractors with such filters, a JD440, CaseIH DX25E and my JD510 has a close mesh screen type filter before the first pump with other paper filters scattered about the circuit.

There's nothing wrong with putting a filter on the return side, just make certain the filter has a built in relief valve, many filters do. There's a cold weather issue (temps colder than 10 degrees F) with filters on a line with potential to build pressure, such as the return line. My example is on the DX25e. It has a second filter between the main pump and the HST unit. In extreme cold weather the manufacturer's recommended filter leaks out all the oil past the filter gasket no matter how tight the filter is. I cured this problem by going to a filter expert at NAPA, who got me a filter that has twice the micron rating that is used only during extreme cold weather months (Dec - Feb). In March I switch back to what is recommended by Case.

I would also like to say that during extreme cold weather, the filter on the suction side of the main pump causes no priming or supply issues. Based on my experience, I prefer filters on the suction side.

 

[J_J]

What you say is true, but the the return filter is recommend by most people.

I have never seen one on the suction side of a log splitter.

Most tractor hydrostatic systems have suctions filters.

Moisture in any filter in a cold climate will cause problems, be it suction or return.

 

[IceStationZebra]

I would also like to say that during extreme cold weather, the filter on the suction side of the main pump causes no priming or supply issues. Based on my experience, I prefer filters on the suction side.

The average mesh filter is only good for about 150-200 micron, whereas generic paper filters are about 40 micron. The mesh "filter" is really used as a trash guard, it isn't fine enough to stop abrasive wear. That is why many systems use a wire mesh filter pre-pump and a paper filter on the return line.

Theoretically before the pump is usually the best place for a filter on offroad machinery as it protects the pump, which is usually one of the most expensive components. But it's usually too difficult to overcome the restriction with cold oil, thus you rarely see it. And just because you don't have "priming" issues doesn't mean that you aren't causing more wear to the pump. It is a tradeoff engineers make to reduce warranty costs. They can not risk manufacturing or the end user letting something get into the system.

Filters are a discussion that could go on for hours. Every application will be a little different. You have to take into account what needs to be protected, what can you spend, space available, maintenance expectations, type of oil, flow constant or varies, filter stable or vibrating, etc.

With regard to your filter issue on the DX25e, did you switch to a winter grade oil? If the oil is so thick that your filter is leaking you should be running thinner oil. Otherwise you could be causing hidden damage to other components that rely on sleeve bearings, small channels and orifices.

ISZ

 

[Mace Canute]

I'm building a log splitter and am to the point of putting the hydraulic system together. My question is about the return line filter. All I see available from Surplus Center for return line filters are typical canister filters of varying sizes but they all pretty much say max 200 psi operation. How is it possible to put a 200 psi filter on a system that has all other components rated for 3000 psi ???? My novice approach is to put every component rated for the same max psi.

Please help.

The splitter will be : 25 gallon tank, 16 gpm pump, auto-cycle valve, 3/4 in lines, splitting cylinder, log lift valve, 3/8 in lines, log lift cylinder, return filter.

Thanks,
-unixkid

Put the filter in the return line.

Anything in the suction line has the potential to cause cavitation in the pump, a situation that will cause many times the damage than the odd bit of debris might cause and since the restriction is there 100 % of the time, so will the cavitation it causes.

If you want to have a screen, put one in the in the filler neck. That way you can see if anything was in the oil you added to the reservoir and you can remove it immediately. Putting a magnet in the bottom of the reservoir to catch any metallic particles that may be present never hurts and can always help.

So many people get hung up on filtering the oil before it goes to the pump but the wear particles that are in the oil come from the system, not from the reservoir...doesn't it make more sense to try to filter them out before they get into the reservoir? Besides...you aren't dumping dirty oil into the reservoir that you have inspected to make sure it was clean from the manufacturer, eh.

Back to the filter...the only thing you have to be careful of is that the filter base has a bypass built into it. The bases I have seen have had a bypass pressure of 25 PSI.

 

[ilander]

Thanks for your in depth reply, very informative. The manual for the DX25E recommends only one hydraulic oil. I just looked up that filter that spits past the gasket in extreme cold weather, it's a 10 micron. The NAPA folks fixed me up with a 20 micron for extreme cold. Also, the filter on the suction side of the pump is a 20 micron. What I have done with this tractor since new is not to work the tractor until the engine temp is normal.

I did some extensive work the the DX25e last summer which included replacing the trans-axle case (it was cracked), it meant complete total disassembly of the back of the tractor. I realize all those gears and bearings swim in this oil, but there was little sign of wear. Also the pump pressure was checked and the cylinders appear to travel as fast as when new. That's the good news.

The bad news, and I welcome comments here, is the HST unit appears to be shot. When cold the tractor travels and works OK, winter operation is acceptable. In the summer the line going to the control valve in the cab gets so hot you cannot touch it, and under a heavy load the tractor wants to stall and the HST chatters.

I see this as my fault, because the plastic fan under the tractor cooling the HST lost all it's blades and I unknowingly ran it pushing and dozing dirt up hill on a few hot summer days, and I think that's what fried the HST as that's when the problem started. Also this tractor is weighted down to maximum weight with attachments (heavy duty dozer on front and one of a variety of attachments on back), so even when just driving it around it is working. I now see cold weather lack of lubrication as possibly helping ruin the HST.

I plan on repairing the HST next summer, but before even starting that project I want to install a oil cooler ahead of the engine radiator. That filter that gives problems I discussed is between the engine driven main pump and the HST unit, I plan on tapping into that circuit just ahead of that filter to plumb that cooling radiator.

Do you see any issues with where I plan on tapping in for the cooler?

Another question, I can disengage the gear transmission and run the HST during cold weather warm up if I want to. I've thought of doing this to circulate and warm the oil because even with the engine warm, when first using the tractor in cold weather it is sluggish until the oil gets warm. Do you see any issues with this running of the HST during warm up? These parts are so expensive I only want to do repair it once, so I want to do anything preventive.