LW-7 suction filter

[kbone1]

I have a JM 354 that has a factory installed "spin-on" hydraulic filter just before the Hydro pump on the suction line. I have read on this site and others that on the suction line you should have no smaller filtration than a 150 micron suction screen. This is said to prevent from starving the pump and overheating/destroying it. My question is, that if the filter has a flow rate higher than the hydro pump it supports, why can't I install a spin-on hydro filter before the pump on the suction line no matter what the filtration rate is? My reasoning is to clean the oil before it reaches the LW-7 control valve assembly and prevent valve trash problems. Has anybody done this? If so how did you/what did you use?

Thank you
kbone1

 

[Diamondpilot]

I would put a 10 Micron Return Line Filter on the return side. These are common on the Return Side of log splitters. If you have a clean system this will remove all the trash that is introduced. You can pick up a setup like I mentioned at any farm supply store like TSC for about $25.

Chris

 

[Bob Rooks]

The LW series suction screens have a built-in bypass arrangement (the spring that holds the screen in place) that is supposed to crack open at around 10" Hg, thus preventing pump starvation. In fact, any true spin-on suction side filter will have a by-pass, either in the head or in the filter itself. Check before you install one. Suction side filtering is very common in the industry, as is pressure side and return side.

Note: Some suction side spin-on filters are available with a 100 mesh screen instead of paper filter media.

 

[RonMar]

As mentioned by bob, suction screen cartrige bypass openings are set in " of HG. A traditional filter is designed to ave fluid pushed thru it and it's bypasses are measured in pounds PSI. That spin-on on your tractor most likley has a #100 mesh(149 micron) screen element.

There is a reason hydraulic systems are built the way they are. If a "filter" on the suction side was a good idea, everyone would do it. That is why they have only a screen.

The best solution for your "trash" problem is to flush out the system and clean out the tank throughly, then put a 10 micron filter on the line returning from the valve to the tank.

There are some schools of thought that say do away with the suction screen all together, as ANY restriction leads to added pump wear and tear. If you keep the tank clean, and filter all the fluid comming back from the valve, there will not be anything in the tank to ever be sucked into the pump right? And you will be filtering to a much finer level than a 149 micron screen element.