In my nearly 20 years in the overhead crane industry, I have witnessed many revolutionary crane technologies that have transformed the way we work. Looking back through the entire history of overhead cranes, I consider the following five achievements to have made the greatest impact on our industry in terms of safety, productivity and equipment longevity.
By Scott McCauley, Technical Support Engineer
Load sensors help reduce mechanical wear
The invention of load sensors greatly reduced problems that had plagued the crane industry - such as shock loading, side loading, side pulls and overloads. When calibrated to 110% of rated loads, load sensors were designed to stop the motion of the hoist if improper loads were attempted. This invention was one of the first major ways to reduce mechanical wear on the crane and promote safe lifting practices.
Variable frequency drives lead to several advancements
After load sensors came the invention of variable frequency drives (VFDs), which have since spawned several other advancements in the crane industry. VFDs were an improvement on previous attempts to negate mechanical crane stress, such as mechanical load brakes, electronic soft-start controls, static stepless and more.
With the digital communication capabilities of VFDs, smart features such as anti-skew were developed. This is important because skewing has been a common industry problem for years. Not only does skewing damage the crane, it also damages the rail and any other cranes on the rail. By using two VFDs running in tandem, through closed loop feedback, anti-skew technology helps keep cranes running straight along the rail, reducing both wheel and rail wear.
Before the invention of sway control, controlling load sway was difficult. Operators needed to be familiar with the unique features of each crane before they could attempt to minimize it. With the load swinging, rope and sheave damage and drum wear were inevitable. Now, through use of VFDs to control speed during starts and stops, sway control enables cranes to move more smoothly without swinging the load.
Another feature derived from VFDs is regenerative braking. This system returns energy back to the electrical grid of the crane. As a result, cranes can operate using less electrical power. In some cases, specifically on port cranes, regenerative braking has reduced energy consumption by 40%.