January 03, 2017
Load sway can be a nightmare for crane operators, learn and understand more about load sway and how to tackle the problem in this article.
When an object is hung from the hook of an overhead crane, it exhibits a natural swing similar to a pendulum swing, when the trolley starts moving or comes to a halt. This is what we term as load sway. Since a long time, crane operators have tried minimising load sway by timing crane movement in a strategic manner. The most common method to control load sway is to make sure that the crane is centred over the load. However, there are chances that the load will still swing before it finally settles down, thereby giving the crane owner no other option than to wait for the load to settle down by itself.
Load sway does not only impact productivity in a negative way, but it also manifests itself as a major barrier to crane safety. This holds particularly true for operators who do not have sufficient expertise in handling overhead cranes. Fortunately, the present-day lifting landscape has seen the introduction of sophisticated technologies that are designed to control load sway and promote productivity and safe lifting operations.
One of such initiatives is the use of variable frequency drives that work by increasing the time a crane will take to assume its full speed limit and to come to a pause, which, in turn, will work to minimise the forces that may lead to sway. Notably, the efficacy of such measures often depends on hook and load heights. This explains why you may find a load that hangs just a few inches off the ground is more stable compared to a crane that hangs midway and is subjected to the forces of sway.
The modern overhead cranes come equipped with advanced sway control features that can be programmed to control the variables that are associated with load-sway. Some of these variables include the height of the hook and the distance between the hook and the bottom of the object.