Crane runways are at the foundation of good crane health. Runways are originally installed to be within the tolerances published in CMAA recommendations. These tolerances are in many cases plus or minus 1/8 of an inch in span and within ¼ inch of each other in elevation. No mater what type of overhead crane system you have in your plant, good runway systems are the key to safety and reduced maintenance.
Aging crane runways can become out of span for many reasons but the most common reasons are building settlement, crane overloads, and crane malfunctions.
Runway misalignment due to building settlement is common to most buildings containing bridge cranes and monorails. Buildings settle naturally anyway but with the added impact loadings that cranes produce they sometimes settle more quickly. This settlement results in runway elevations and spans becoming out of tolerance.
Crane overloads can lead to permanent deflection to bridge support columns and crane runways causing them to be out of tolerance. This out of tolerance condition will tend to worsen over time if left unchecked.