Online Equipment Focus on Haul Trucks: In It for the Long Haul
- Are the samples’ locations oriented properly in relation to the filter?
- Does the arrangement allow the technician to obtain a sample without introducing contamination (oil runs down the side of a sump and into the bottle, etc.)?
Pin and bushing wear assessment. Where possible, slop (or play) limitations in an axis of normal wear should be defined and easily measured. Much of this is established when the connections are designed, but a few simple measurements often can significantly improve the assessment capability.
Structure inspections. This most basic maintenance action becomes much more effective and efficient when guidance is provided on where and how to inspect (visual, non-destructive testing, etc.). Obviously, some areas of the structure are more critical and susceptible to cracking, while other areas experience low stress and do not require as careful an inspection. Additionally, to further improve the ability to monitor structural condition, cracking thresholds are necessary to explain what amount of cracking requires immediate repair and what can be scheduled for future planned down periods.
Collect basic data and use it
Based on the characteristics of the given equipment and operating environment, logical individual threshold values need to be clearly defined. When thresholds are exceeded, logical and realistic corrective action should be specifically explained.
If the thresholds and limits are not readily available, the original equipment manufacturer may have helpful information. Alternatively, initial numbers can be determined based on your crew’s experience with the equipment. If any of the above sampling/inspection steps are currently included as part of the maintenance program, someone is making judgment calls on the appropriate corrective action. Thresholds and limits currently used by resident experts need to be collected, quantified where necessary, validated, and formally documented. This information will allow decisions to be made in a consistent manner and eliminates complete dependence on any one member of the maintenance crew.
Additionally, once initial thresholds and limitations are established, basic data analysis allows the numbers to be refined and improved. A comparison of the conditions observed that prompts a component removal or system disassembly can be compared to the actual condition found. With a reasonably small set of data, solid conclusions can be drawn.
For example, the iron (Fe) level in a bearing sump may be 25 parts per million (ppm) and shows an increase of 10 ppm from the last reading. The bearing is pulled from service, and the condition is considered excellent. Over time, it is determined that similar scenarios occurred with a few additional bearings of the same type in the same application. Therefore, a reasonable conclusion could be to raise the threshold to 40 ppm and see if any wear is noticed when bearings are disassembled and inspected.
Another example might include a measurement of 0.095 inches of slop on a particular pin/bushing connection. The bushing is almost completely worn through, and cracking is observed in the adjacent structure. If similar observations are documented for this same connection, it would be reasonable to lower this slop limit, perhaps to 0.08 inches.
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