I'm not an equipment manager, but I've spent 20 years talking with equipment managers about how they maintain equipment, and with equipment manufacturers about how they design hydraulic systems and with lubricant marketers about what they expect from hydraulic oil.
It seems to me you have two choices on how to maintain hydrualics:
1) Use regular oil analysis (that includes particle count and spectrographic analysis -- like they use on engine oil -- as well as some measures of viscosity and water content) to decide when to change oil. Primarily, you want to know if the oil is clean enough to protect your valves and seals, if it's being overheated, and if there is any water in it. Use that information to decide how the oil should be filtered and when, or if, it should be changed.
2) Follow the manufacturer's maintenance recommendations. You should use the same oil analysis described above at least for the first few oil changes to confirm that those recommendations are adequate for your application.
If you're not doing one of those two, any hydraulic-system problems you're having are really your own fault.
Oil analysis is essential in either case because, let's face it, manufacturer's service recommendations, especially for hydraulic systems, are shots fired in the dark. They have smart engineers looking at component design parameters and extensive testing data, but they got no idea how you are using your hydrualic system or how good your hydraulic oil is. And variation in how hydraulic systems get used in the world are so diverse that they can only pick a conservative middle-ish point and say, "There. That's when
most people should change their hydraulic oil."
In my opinion, if you want to manage hydraulic systems for minimum downtime and maximum bang for the buck spent on labor and materials, you have to know your own hydraulic systems pretty well. You can best do that with thorough oil analysis (particle count, spectrograph, and chemical tests). And you're best off sampling every other engine-oil change or so (close to 500 operating hours). You can always reduce frequency if the results prove pretty consistent.
The people I've spoke with who have researched and attacked hydraulic-system problems have all started with rigorous oil analysis programs. And they've all implemented fairly similar measures. They get militant on hydraulic cleanliness. A little contaminant (dirt, metal, water, anything) always creates a lot of contaminant -- mostly metal off the interior surfaces of valves, cylinders, pumps and motors, but some rubber off of seals, too.
A surprisingly high percentage of the best managers find themselves having samples of new oil analyzed. Anybody who's run particle counts on the oil they receive at retail -- either from a bulk truck or in packages -- knows how dirty the stuff is when it's sold to them.
It's dirty -- seldom meets the hydraulic-component manufacturers' target cleanliness levels for acceptable component life. Run it through a filter with specs at least as good as the finest filter in your machine's hydraulic system. Lots of people use a filter cart with much-higher-efficiency filters to get the stuff clean. They convince their jobbers to filter the oil coming out of their trucks into their bulk tanks (and they specify the efficiency of the filter), and then they put filters on their own bulk tanks and trucks or other dispensers to filter the oil before it goes into the machine's hydraulic tank.
You don't have to be an engineer to do this. Get JLG to help you out. They have good people. Just push up the chain until you find somebody who knows hydraulics and will help you with your system. If you can't find anybody at JLG, go to the hydraulic-component manufacturer. But don't go empty handed. Make sure you have some oil-analysis history and component-life history defined and in hand. Define your problem and challenge them with it.
You need to clearly establish housekeeping rules for maintaining the cleanliness of oil in storage, oil in transit, and oil being poured into a machine's reservoir. If you don't make it clear that they can't pour make-up oil into a dusty bucket, or one with a bunch of antifreeze residue still in it, they will do it. You will not reach the hydraulic-component manufacturer's target cleanliness without these measures.
Write policies for replacement hoses. Spec them carefully. Make sure the couplings match properly, and the hoses will stand up to your application.
Tolerate no weeping seals. As soon as dust starts to cling to cylinder rods, the cylinder is allowing dust into your hydraulic system. You need new seals.
Install dessicant reservoir breathers with high-efficiency filters on machines and bulk tanks. Your hydraulic systems, unless they're the sealed type, suck gallons of air off the job site every time the operator runs the boom out. You don't want the dust and humidity in that air in your reservoir. Establish a service interval for those breather filters and follow it.
A remarkable number of people I've spoken with about hydraulic-system maintenance use high-efficiency filter carts (filter buggies, kidney-loop filters, dialysis machines, lots of different names) as part of their maintenance program. It's basically a cart with a pump to push oil through some very-high-flow, high-efficiency filters. They use oil analysis to establish an effective interval where they go in and change a machine's hydrualic filters and run the oil in the reservoir through the filter cart. Often it's at that 1,000-hour interval, when the service man's going to be working on the machine for a while anyway and the cart will have time to polish the oil.
As long as the oil's not being overheated, and you're maintaining improved oil cleanliness (lack of contaminants AND water), you should see better hydraulic-system reliability. And you should never have to change the oil.
Here's one angle on improving hydraulic reliability and component life.
Prevent Leaky Hydraulic Systems
Here's a story about how Waste Management attacked the problem of poor hydraulic-system life (yes, a very different application from yours, but they are approaching hydraulic system maintenance just as anyone should).
Waste Management Cleans Hydraulics To Cut Costs
C.J. Miller spends 45% more on maintenance but saves money by reducing maintenance frequency
How to Reach Hydraulic Cleanliness Targets
Sorry about the diatribe, but this is a subject that I consider to be really crucial to operating equipment cost-effectively, and one that I've studied pretty intensively.
Hope this helps,
Larry
I guess I could get it tested like engine oil. What are you changing it at and what types of machines? I guess it gets sheared up and loses additives?
