Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/120548
Hydraulics HYDRAULICS AT WORK BRENDAN CASEY Which Hydraulic ISSUES DESERVE More ATTENTION? At a recent site meeting where I was investigating a series of premature hydraulic pump failures, the client opened the proceedings with a brief history on the machine, an account of the events leading up to the failures and then pushed a stack of oil analysis reports across the table. After I finished taking notes on what I'd just been told, I inquired about the hydraulic system's normal operating temperature range. An uncomfortable silence filled the room. Eventually, the client shrugged his shoulders. I then asked about the hydraulic system's operating pressure range. With a blank and partly worried look, the client replied, "Err… dunno. We don't monitor either of those things." The Importance of Visual Inspections Many equipment inspections are visual, and checking oil levels is the most common visual monitoring activity. Numerous potential machine failures are prevented by an attentive individual who notices a low or nonexistent oil level. Other valuable functions can also be performed as part of the visual inspection. Lubricant issues such as oil contaminated with water or other materials, badly degraded or oxidized oil, and excessive foaming, as well as other machine conditions including excessive vibration, loose belts, loose drive chains and loose or missing fasteners are all examples of what should be routinely documented and scheduled procedures. This should serve as the foundation of a condition monitoring program, no matter how sophisticated. At the end of the meeting, we took a walk to the control room. As it turns out, both operating pressure and temperature were displayed on the default screen of the programmable logic controller (PLC). This crucial data, from a reliability perspective at least, was hidden in plain view among a lot of apparently more important and closely watched production information. In my experience, such narrow concentration of attention within departments is not uncommon. The result is something called inattentional blindness — too busy looking at one thing to see some other thing that is equally or even more important. It might sound trivial, but inattentional blindness can be fatal. 24 | March - April 2013 | www.machinerylubrication.com 90% of lubrication professionals say a lack of attention has negatively impacted the reliability of equipment at their plant, based on a recent poll at machinerylubrication.com On Dec. 29, 1972, Eastern Air Lines Flight 401 was forced to abort its initial approach for landing into Miami, Fla., because the light that indicates when the plane's nose wheel is down and locked into position had failed to illuminate. After flying around and pulling up to 2,000 feet, the captain and his co-pilot became so fixated on the suspect light fixture that they failed to notice that the autopilot had been disengaged. As the plane dropped through 1,750 feet, an altitude warning alarm, which was clearly audible on the black-box recording, went off in the cockpit. However, both pilots were so focused on the light fixture that neither of them consciously registered the noise. Co-pilot: "The tests didn't show that the lights worked anyway." Captain: "That's right." Co-pilot: "It's a faulty light."