There are various periodicals related to manufacturing and industry, and at least one trade publication I am aware of is dedicated to the maintenance and repair of industrial machinery. Hydraulics dominates most sectors of manufacturing, and this is especially true in heavy manufacturing, so I find it odd the particular magazine I’m referring to rarely or ever touches on fluid power.
The simple bearing appears to be the golden child of plant maintenance, which is obviously important to be greased and/or oiled with some regularity, but there is only so much to be discussed about their operation and upkeep that I find it odd they get so much attention, especially compared to hydraulics. I am biased, however, and I’m sure the guys at SKF say the same things about hydraulics that I say about bearings.
Hydraulic maintenance is important, of course, but it’s not the mechanical components of the pumps, valves and motors that need regular attention. Sure, you could replace the seals in a cylinder at regular intervals to avoid spontaneous failure, but I doubt any maintenance calendar is penciled with “March 28th, 2013: micro polish valve spool and document spool to body clearance.”
Rather than preventative maintenance on actual mechanical components, the important part of a hydraulic system to focus the majority of maintenance on is the fluid medium itself. If you spent 95% of your allocated hydraulic maintenance time on the conditioning of your fluid, your reactive maintenance schedule would clear up like a hillbilly’s dance card at an international grand ball.
Keep your oil clean, dry and cool. If you focused all your energy on those three qualities of your hydraulic oil, your machines will pay you back with productivity, longevity and plutonic hugs. Keeping oil clean is probably the most overlooked principle of fluid conditioning. I don’t know how many times I’ve heard the following quip after a hydraulic failure, “We just changed the filter last year.” Sure, filters can last years, but people don’t confess that the filter was a nominal 25 micron cellulose spin-on unit that couldn’t filter the stones out of the bottom of a fish tank.
There is no such thing as oil being too clean, but if you want to sacrifice your $300,000 machine to the gods because you thought a $1000 filter was too expensive, then maybe it’s your fault when you have a $15,000 repair bill. One thing to remember is that dirty oil wears away surfaces, which creates further contamination and subsequently more wear. Fine filters may need more frequent replacement, especially soon after being upgraded from a lower quality element until the excess contamination is removed, but they’ll eventually keep oil so clean as to prevent component wear from contributing to the problem. You may even extend filter life!
It’s time for me to go, but choke back those tears, as I’ll be back again soon with a blog about dry oil.