Cranes

BEAR has extensive experience analyzing the failures of both large and small cranes and heavy other lift components.

Milwaukee Brewer's Stadium

One of the largest crane failures analyzed by BEAR engineers is the 1999 Milwaukee Brewer's Stadium crane failure. The Lampson Transi-Lift 3 (affectionately known as Big Blue) was one of the largest cranes in the world, specifically constructed to lift 1 million lb sections of the stadium roof.

After examining the evidence it was determined that the failure was caused a by poorly designed kingpin (large pin that allows the crane to rotate) and high winds at the time of the accident.

San Diego Construction Crane

Another example is a 250 ton mobile crawler construction crane in San Diego, which experienced a clutch failure that cause the crane to drop its load onto an iron worker. In this case, in addition to the visual and material inspections, BEAR also performed a detailed three dimensional finite element analysis demonstrating the effect of poor clutch maintenance on the performance of the clutch.

To see a video, click here.

Smaller Cranes

BEAR engineers analyze and consult on smaller cranes also. The most common problems are (1) tipover due to outrigger problems, (2) cable clutch slippage due to lack of inspection and maintenance, and (3) fatigue of base bolts due to poor design and heavy use.

The truck crane at right dropped a load due to clutch slip in the cable hoisting mechanism. The hydraulic drive motor required periodic inspection of clearances to maintain position following a lifting operation. The failure was recreated in BEAR's laboratory using a drive unit rebuilt with worn components and a crane both built by BEAR mechanics and technicians.

Heavy Lift Failure

Heavy lift failures also occur due to failure of rigging components and clamps. The beam clamps at right were being used to hoist a 7,000 I-beam when one hung up and caused the beam to rotate and drop 200 feet to the ground taking a worker with it. The shape and closing mechanism allowed the accident to happen.

Crane Load Cable Failure

In another case, a crane load cable failed during the construction of an overpass at the San Francisco International Airport. In this case, a full mathematical analysis indicated that incorrect rigging of the crane had led to the failure of load cable.

Heavy Lift Derricks & Cranes

BEAR engineers regularly consult on heavy lift derricks and cranes from the Port of Oakland to offshore lifting of oil production platforms, process equipment and bridge sections with heavy lift derrick cranes as shown below: