B2710 Hyd strainer

[MarkLeininger]

So you really think the strainer is there just to catch the bits when something explodes?

But anyway I didn't say theres grit in the oil. I said it gets trapped in the strainer and ultimately clogs it. Are you aware how fine the mesh of this strainer is? Its almost as fine as cloth. Perhaps you are thinking its coarse like a veggie strainer.

I think the strainer is like the net under a highwire act. Everyone hopes you don't need it, but if you do it's there. How does the grit get into the strainer if it's not carried in the oil? Do you mean grit like from checking the fluid level and wiping the stick with a dirty glove, or are you saying the engine somehow produces grit? We need a card carrying mechanical engineer on this group to answer questions like this. Kubota paid an engineer to design this strainer, we need to track that person down and ask them why they got paid to put a strainer in this tractor.

 

[MarkLeininger]

I talked to one of the mechanical engineers at work. His expertise is cryogenics, but he had some books and papers on hydraulics. Most of it was impenetrable, but there was an interesting section on strainers that I could almost understand. Here's the text:

"However, the majority of components of contaminants in working hydraulic systems are not solid particles like ACFTD but toluene soluble resinous matter, as shown in table 2. Resinous matter has polarity and is adsorbed onto metal surfaces. It is sticky and attracts other solid and fiber contaminents which then stick to them. By this mechanism, suction strainers will be clogged.

A suction strainer is actually a full flow filter. Hydraulic oil passes through a suction strainer at very high velocity. This means that both oil and the strainer will be electrified by friction of oil with the strainer. When oil passes through insulated strainers, static electricity will be accumulated on the strainers and the accumulated electric charge will be discharged by sparks. Spark discharge of static electricity will crack oil molecules and produce free radicals. Free radicals will propogate autoxidation of oil and produce polymerized oil oxidation products (resinous matter). This cycle continues, as long as full-flow filters are used in hydraulic systems."

I found a fair number of anecdotal postings on the internet that strainers are put in by manufacturers to prevent maintenance claims due to poor manufacturing processes that leave nuts, bolts, and tools in the hydraulic system. However they do more harm than good because they get clogged and cause cavitation. The suggestion was to remove the strainers because they aren't necessary and only create a problem.

So, now that I agree my strainer is probably full of grit (sticky resinous material that attracts other crap), I'm headed out to clean it.

 

[alchemysa]

Good idea. Please let us know what you find. (You didnt mentiont if you have a HST by the way). By 'grit' I meant generally anything that shouldnt be there. Even a perfectly built and cleaned engine is going to loose fine metal points off the gear teeth. These tend to sink to the bottom of the tranny case where, in some models, the oil take offs to the HST and other hydraulics tend to be, so they'll go through the HST before they reach the replaceable oil filter. (??) Your comment about the static electricity is very interesting. Some of the later model Kubotas have dropped the strainers, perhaps for that very reason.

Having said all this, I dont actually know if your model even has strainers, but if it does, and you have a HST, you will usually have one strainer each side of the tranny case.