# Filter on Splitter Feed or Return line?



## NoPaint (Feb 4, 2011)

On what oil line do you have your splitters filter?


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## WhitePine (Feb 4, 2011)

This is generic in nature, but would apply to just about any run of the mill log splitter. I don't currently own a splitter (I'm looking at several), but do have some hydraulic machinery which I maintain.

You can generally find filters in one of three different places on a hydraulic system, suction line, return line, and high pressure line.  High pressure filters are expensive specialized devices best left to experts. Suction line filters protect the pump directly and can be obtained at reasonable prices from places like https://www.surpluscenter.com/. They also carry return line filters.

Suction line filters can cause pump destroying cavitation if not done right, or if not changed at regular intervals.  Return line filters can cause excessive pressure to build in the return line if allowed to clog, which can cause the filter to rupture. If the machine is equipped with a cheap low pressure return line, it too may rupture.

Some simple hydraulic machines, including splitters, which have only three or so hydraulic components, don't have any filter because the value they provide is minimal compared to something like a tractor, which usually has numerous cylinders, a raft of valves, and sometimes multiple pumps. The main purpose of the filter is to protect as many hydraulic components as possible in the event of a failure of any one of them. Unfortunately, a pump failure will often damage numerous downstream components such as cylinders and valves.  Neither a return nor suction filter will not protect against this, but they will help prevent damage to the pump and other components if the event of a cylinder failure, except for the cylinder's associated control valve. 

The most likely candidate for catastrophic metal shedding failure on a log splitter is the pump. As stated in the previous paragraph, a suction or return line filter will do nothing to prevent the debris from reaching the control valve(s), the cylinder(s), and the tank, which is why they are sometimes omitted--beside the obvious cost savings to the manufacturer. Replacing the valve, cylinder, and pump are bolt-on operations. Cleaning _*all*_ the trash out of the hydraulic tank is another matter. But a return line filter _will_ capture most of the trash. limiting future damage from hydraulic tank contamination.

Neither suction nor return filter will do first class job of cleaning the hydraulic oil simply because they must be coarse enough to allow large volumes of oil to pass without the danger of collapse of pressurization. In order to really clean the oil, a second parallel filter can be added to either a suction or return filter. These are known as kidney filters. The have a much smaller micron rating than the main filter. Two microns or even less can be used. 

Kidney filters work by continuously cleaning the small stream of oil that flows through them. Eventually, all oil will pass through the kidney filter and virtually all small containments that would pass clean through the main filter will be removed. The kidney filter must be replaced on a regular basis or it will simply clog and become non-functional. Sometimes kidney filters are part of a completely separate circuit mounted on a workshop cart. An electric pump circulates the hydraulic fluid. Kidney filters are overkill for home use wood splitters, but might be a good idea for commercial wood splitting operations.

The bottom line for the average user is a return filter, unless your hydraulic tank has a clean-out, a removable plate the allows unrestricted human access to its interior. If a clean-out exists, my preference would be for a properly done suction line filter.


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## LLigetfa (Feb 4, 2011)

Mine is on the return line.


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## NoPaint (Feb 4, 2011)

Sounds like return it is.  I am eyeing a new one with spin on filter currently listed on ebay.  I'd like to figure out what size lines I have so I can get two new lines and whatever fittings are necessary to make all this macho-ness work.  A good filter should keep the system happy.


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## bogydave (Feb 4, 2011)

Mine is between the Hyd. tank & right before the suctions of the pump. 
Speeco splitter


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