FireEngineering recently published a guide emphasizing the importance of aerial apparatus inspection, testing, and maintenance. The following is an excerpt about aerial cables / wire rope. The entire article can be read here.
Fire service apparatus advances can be divided into numerous areas and according to numerous benchmarks often tied to operational safety. Providing an increased margin of safety has driven practically every aerial apparatus change and advance. Today's aerial apparatus are infinitely safer than the aerial apparatus of more than 25 years ago and measurably safer than aerials that are only 10 to 15 years old.
Practically all aerials rely on a system of cables to synchronize and support the fly sections of the aerial device. Operators must consider three essential elements when checking the cables during an inspection: tension, condition, and lubrication. You can verify each of these items without using specialized tools or taking an exceptional amount of time; include them as part of the overall apparatus inspection. Cable tension is formally measured with a specialized tool, a tension gauge; but at the company inspection level, investing in such equipment or training on it is not needed. A contractual service provider can perform this function, comparing the measurements obtained with the aerial manufacturer's specification. Aerial operators can be fair judges of cable tension based on their experience and observing the overall movement of an aerial. Although proper tensioning is important, at this level, the goal is to identify those cables which excessively slack or whose tension is grossly mismatched with that of the cable on the opposite side.
The overall cable condition is another visual inspection in which the operator examines the cables for signs of damage, defects, broken strands, or unraveling (bird-caging). Through regular maintenance and proper operation, the chances of an aerial cable becoming damaged is remote, but it is still possible, and a close inspection should follow any unusual operation, loading, or collision.
Finally, all cables and wire ropes require proper lubrication to ensure longevity and smooth operation. Cable lubrication is likely one of the most misunderstood elements of aerial maintenance, yet it serves a critical purpose. Cable and wire rope have two wear points-the outer circumference that rides in the sheaves and the inner strands that pull and twist against each other as the cable is loaded and unloaded. To provide proper lubrication, ensure that the outer surfaces and inner strands are evenly lubricated.
Lathering with a heavy lubricating grease is absolutely the worst way to lubricate a cable and will provide users with a false sense of the cable's condition. Furthermore, that heavy coating of grease will attract and hold dirt and debris (photo 5) while concealing visual cues of damage or defect. Depending on the aerial manufacturer, the specific brand and type of approved cable lubricant can vary, but manufacturers generally specify a lightweight cable and chain lubricating oil in a spray or a wipe-on formula.
Do not saturate cables so that they drip oil as the aerial is extended or retracted. This does not improve performance or longevity and can create a slip-and-fall safety hazard on the walking surfaces above the aerial turntable and on the rungs.