I’m currently living in the Snowy Mountains region in eastern Australia, near a small village called Jindabyne, which is about 5 hours drive from Sydney. Jindabyne is 3000 ft (944 meters) above sea level.

As you’d expect, I regularly see hydraulic machinery working on roads and construction sites in the area and I often wonder how they perform on a hot day. Because at 3000 ft, air only has 90% of its sea level density. So a fixed-speed cooling fan will move the same volume of air but at only 90% of the mass–and it’s the air mass that removes heat from the hydraulic oil’s heat exchanger.… continue reading »

A large part of being “smart” in any area of expertise comes from doing your homework. And this is especially true with hydraulics. Here’s a story from one of our members which illustrates this point pretty well:

“I’m fairly new to hydraulics and I thought coating the interior of a hydraulic tank I’d made with a zinc spray (cold galvanizing in a spray can, like paint) would be a good idea. The idea was fine but the reality was not so good. I had no way of predicting that the components of the oil would dissolve the zinc coating… I’m fortunate that there is little I could do at this point that would further endanger my soul.”

Call me superstitious, but I’m not a fan of painting the inside of hydraulic tanks, period.… continue reading »

In the appendix of Reliability-Centered Maintenance II, John Moubray lists 102 proactive maintenance techniques in six categories:

1. Dynamic effects: monitoring of vibration, pulses and acoustic emissions (17 techniques)
2. Particle effects: monitoring of particles in the component’s operating environment, e.g. lubricant (15 techniques)
3. Chemical effects: monitoring of chemical elements in the component’s operating environment, e.g. lubricant (27 techniques)
4. Physical effects: monitoring of surface cracks, fatigue, wear, etc (24 techniques)
5. Temperature effects: thermography (4 techniques)
6. Electrical effects: (15 techniques)

While extensive, Moubray’s list is by no means exhaustive. And new predictive techniques are being devised or invented all the time.… continue reading »