Spin-on hydraulic filter

An excellent topic Milo!
The older Kubota tractors have limited filtration capacity due to the simple screen Kubota used. More recently they have done exactly what Milo suggested and incorporated a inline spin-on type filter, which is not only able to filter much finer particles but has a much larger filter surface area too! A vast improvement! They have left the screen in most of the tractors ,which in my mind is a mistake because most folks don't know it is there so it doesn't get cleaned AND it is so horribly tight that many people can't get it out. If it were my tractor and it had a spin on filter that screen would only come out once! The only problem retrofitting another filter is finding a convenient place for it where it doesn't get knocked off.
Ed

Most Hydraulic filters for the suction side are about 25 micron. You can go a lot finer (10 or even 5) if you are filtering the high pressure side but you don't want to restrict the oil flow to the pump any more than you can help. 25 is WAY better than most screens!
You Can also filter on the high pressure side. Some equipment filter the return oil but that isn't very convenient on a tractor but you could easily filter the tank line from your loader. this would prevent contaminants from the loader from ever getting into the system. It could be a much smaller micron filter. Something else to think about! we'll have filters sticking out all over the place but won't we have the cleanest oil?
Ed

Milo Holroyd said:

Thanks for the reply Ed.
I will post my progress on this thread. Memory fails me at the moment, is a 25 micron filter sufficient?
Milo

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Milo you are on fire with great ideas! Here's a thought with your latest project... in my business, ( Aerials ) we don't use any return filtration smaller than 20 Microns. There are several reason based off of particulate size and harm to the system why we have found this level of protection to be a happy medium. PLease find attached a couple simple formulas with a diagram for thought while deciding your needs.

Hi OB1
You're going to have to explain those charts you sent some! What do you refer to re "return filtration"? Do your aerials mostly use Closed center systems with a charge pump?
Ed

Ah ha.... I would be giving up proprietary info there, but the diagram is a very simple diagram of a test filtration system that can be used on both pressure or suction. A fixed pump with a variable flow device, parallel Compound gauges and separate fluid tanks one of which has a shut of valve. The idea is to cycle the system with different levels of contaminates induced into the system and measure the wear your components see during the beta testing. Beta testing is a term used in the development of prototype system analysis in several manufacturing disciplines. Thats about all I can offer on the subject. Its nothing more than a simple flow system used in Beta Testing. There's a whole occupation ( Job Title ) for Filtration Engineers whose goal is to clean the fluid to a point that abrasive (Contaminates) are not factors in the catastrophic, degradation, or intermittent failure of all the components in the hydraulic systems useful life cycle of the maintainable performance. Hope this helps....

eserv said:

Hi OB1
You're going to have to explain those charts you sent some! What do you refer to re "return filtration"? Do your aerials mostly use Closed center systems with a charge pump?
Ed

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Ed over the years we have used several varieties of systems... depends on the customer application, whether A Class voltage, etc. The "hot' system now is the variable displacement electronic positioning, pressure compensated, load sense, fixed displacement closed center, fixed displacement variable drive, just off the top of my head. If you have a need for one of our specific systems I'd be more than happy to send it to you.

we are getting way more technical here than is required to clean up the oil on a little old Kubota! Milo has a great idea here, lets not bury it with over-complication. The filtration requirements of a relatively low pressure open center system, especially with a gear type pump is low. A 20-25 micron filter is quite adequate to do the job. More important to us than the filtration efficiency of the filter is whether it is capable of flow we desire without creating excessive pressure drop. Here again we are "saved" somewhat by our gear pump which is able to operate comfortably with considerable negative head at least compared to piston style pumps. For our purpose, if we use a filter similar to the one Kubota use on the newer tractors, we'll have a winner.
I'm sure I could hold my own with you discussing open center, closed center, load sensing, pressure compensated, pilot operated, pressure intensification, flow compounding, series filtration, bypass filtration, or whatever you want to talk about. If we ever get together over coffee someday I'd love to have that conversation too! I'm sure you can teach me something! But I don't think it would benefit any one except you and me on this forum and certainly wouldn't help Milo decide what filter to install on the ol' 245!
Ed

Okay Ed you ask me to explain and I did so in the most simplistic way possible under the circumstance. I've always been sincere up here trying to help and Milo strikes me as a person who goes above and beyond with a machinist background and would appreciated the advanced knowledge. You need to just blow me off bud for what it is and remember there's no fight here in this old dog just a lot of experience with engineering. If you hadn't come up with the 10-5 micron statement I wouldn't have said a word.

You are right! I shouldn't have brought up the subject of 5-10 micron filters. they just don't apply to this application. Would you say Kubota shouldn't be using them for hydrostatic filters? We can just use a cheap 20 micron filter instead and the equipment will be as well protected?
Ed