Maintaining crane stability is absolutely essential to keep operations safe for people and to prevent costly damage. Stability issues become particularly critical with mobile cranes, as they are expected to function in a variety of uncertain and potentially hazardous environments.
That is why mobile crane operators, construction personnel, and planners should be familiar with threats to crane stability and know how to respond accordingly. Below are two common, but essential, stability issues that need to be addressed before and during a job.
A significant threat to crane stability is the wind. It is easy, but misguided, to think of the wind as an annoyance rather than a real danger. The reality is that wind forces can easily knock over cranes and cause tremendous destruction in the process.
The threat from wind affects cranes both directly and indirectly. The direct threat is present whenever wind exerts a horizontal influence on a crane structure itself.
In particular, the boom and jib are vulnerable to high winds due to their greater elevations. Not only that, but the larger or taller the crane, the larger the surface area to be blown against by winds, which also increases the threat of tip-over.
Indirectly, wind can also affect a crane's stability by acting upon the load. Large loads with lots of surface area, even those with minimal weight, are subject to increased wind-caused instability. This has led to catastrophic accidents due to the tendency of these objects to become "sails," thus dragging a crane or pulling it over altogether.
Preventing accidents initiated by the wind is a matter of understanding when and when not to conduct operations. Cranes are rated with an in-service wind speed maximum; once wind speeds exceed this number, operations must cease to prevent possible tip-overs.
In addition, cranes should also be stowed during high wind events. It's not enough to merely stop using a crane in high winds, for example, as the boom and jib should also be lowered into a safe position.
Another important threat to crane stability is inadequate footing. Many times, mobile cranes depend upon sure, firm ground for safe operation; the likelihood of a tip-over or other accident is increased if cranes don't have a predictable foundation upon which to operate.
Of course, some cranes are designed to traverse difficult terrain and can handle more uncertain footing than others. However, at the end of the day, soil instability and generallyd poor footing conditions will negatively affect most cranes to some degree.
Unfortunately, the demands of construction or repair don't always give crane users the luxury of working on perfect ground conditions. To help compensate for poor footing, crane mats are useful in creating predictable operational surfaces.
Crane mats are built by linking large timber stringers, usually made from oak. The stringers are attached to one another, thus forming a "boardwalk" upon which to operate. Crane mats are placed directly upon poor working surfaces and can be moved as needed to a new on-site location.
Alternatively, the ground may also be improved via soil compaction and the use of augmentation techniques. For example, gravel and sand may be added to a site to provide a firm, reliable pad for crane operations. This type of augmentation work will increase costs, of course, but it may still be justified based on overall budget and the length of time the crane will be on site.
If you are unsure about operating a crane in a safe, stable manner, never guess or rely upon an inexperienced operator or crew. Instead, be sure to contact a knowledgeable authority at a company like American Equipment Inc to obtain help. Their expertise may be the difference between finishing a job on time and on budget or facing the aftermath of a devastating accident that costs money and possibly lives.