HST Filter

[s219]

Someone said no photos. Here's the difference between a Napa/Wix and Kubota High Pressure side hydraulic filter for an L3940 and many other models.

NAPA 7616. I think it's fairly obvious that Wix took an existing filter and machined an adapter and screwed onto a filter for something else. The NAPA only has four unobstructed holes in it. The Kubota has 6 unobstructed slots. My son can get the NAPA filter for about half the price of the Kubota but will not buy another one. He gets a very generous Fleet discount on filters. BTW: The low pressure side filter, a Kubota HHTA0-37710, the recess in the NAPA will not accept the magnet from a Kubota filter, the recess is the wrong size. The NAPA filter 7098 doesn't come with a magnet.

That's quite a significant difference. I have heard about the magnet issue several times before, but I'd say the difference in flow area is a pretty big deal. Looks like less than 50% the flow area of the Kubota filter, plus it's unevenly distributed.

 

[rScotty]

That's quite a significant difference. I have heard about the magnet issue several times before, but I'd say the difference in flow area is a pretty big deal. Looks like less than 50% the flow area of the Kubota filter, plus it's unevenly distributed.

The filter is fed by oil under pressure. As long as the filter openings are greater than the pipe feeding the filter, wouldn't the resistance of the filter media itself make substantially more of a difference in flow?? And anyway, isn't it filtration we are concerned with more than flow?
rScotty

 

[s219]

The filter is fed by oil under pressure. As long as the filter openings are greater than the pipe feeding the filter, wouldn't the resistance of the filter media itself make substantially more of a difference in flow?? And anyway, isn't it filtration we are concerned with more than flow?
rScotty

It all depends on where the restrictions and losses are. Keep in mind that flow losses scale up with velocity and surface area, and also increase the more orifices you have. Many small holes will be a lot lossier (higher velocity, more surface area, more edges) than fewer larger holes even if the area is the same. Anything that creates a pressure drop is bad and pressure drops are additive. I'd assume the filter media is already a pretty large pressure drop, so I wouldn't want to add more restrictions in the system.

Now on the other hand if the filter media creates such a huge pressure drop that everything else is peanuts in comparison, it may not matter. But that's not something we can answer without more data and some calculations. Me, when I look at the NAPA filter, I am not liking the reduction in open area of those orifices, nor the non-uniform spacing and distribution. And when I eyeball the area of the small orifices (normally the inflow) and compare to the outflow (normally the center hole) the orifices clearly have less area.

 

[Fallon]

The filter is fed by oil under pressure. As long as the filter openings are greater than the pipe feeding the filter, wouldn't the resistance of the filter media itself make substantially more of a difference in flow?? And anyway, isn't it filtration we are concerned with more than flow?
rScotty

Restricted oil supply will cause cavitation & destroy a pump faster than contaminated oil. Hence why hydraulic filters are usually on the return line, not suction. HSTs are even more sensitive soi believe their filters are after the charge pump, before the HST. Hence needing to be a stronger filter & canister to deal with charge pump pressures.

 

[David_Kb7uns]

Just like the horrible 50 micron filter screen WIX/NAPA spec for the BX in place of a paper element water blocking diesel fuel filter, they will spec anything to make a sale with little regard to what happens to the machine afterwards.

Would not use a WIX filter on a YUGO!

WILL FIT IS NOT AN OPTION use a filter designed for the application!

David