Self-erecting tower cranes run the risk of tipping much like mobile cranes.
In some cases, self-erecting tower cranes are replacing mobile cranes because of their efficiency in travel and set-up. Self-erector set-up is similar to mobile crane set-up. Both require firm, level ground with extended outriggers or stabilizers. Counterweights must be installed per the manufacturer’s specification like most modern mobile cranes.
Unlike traditional tower cranes, which experience structural failure if overloaded, self-erectors are more likely to tip over. However, like mobile cranes, self-erectors are difficult to turn over because of their large structural design factors and required load chart safety margins.
Our Tower Crane Operator & Inspector covers hammerhead, luffing, and self-erecting tower cranes.
See also Flat Top Luffing Tower Crane.
Something went terribly wrong while three cranes were moving the bow section of a ship in a Mississippi shipyard. One crane overturned and several workers injured.
Cranes are designed to smoothly lift and move loads within their capacity with the boom tip directly over the center of gravity of the crane’s load. When multiple cranes are working together, they share the load, but neither have the load positioned over the center of gravity.
As you can imagine, things become more complicated when three cranes are working in tandem, because the movement of a load has to be perfectly choreographed. In this case, the only safe maneuvers made would be to hoist, lower and travel. Hoisting and lowering shouldn’t be a problem as long as each crane’s share of the load is within its capacity. However, traveling induces dynamic forces on the cranes because they don’t travel in perfect synchronization. Like all equipment, cranes travel at random speeds no matter how careful the operators are to synchronize their speed. Being off by a small amount causes what could best be described as a pushing and shoving match between the cranes.
Industry accepted lift planning models for multiple crane lifts would require that no crane be loaded beyond 75% of capacity. This 25% safety margin is used to compensate for the dynamic forces.
Attend our Mobile Crane Operator training to learn safe operating practices.
Read more at Heavy Lift News
Today’s heavy lift cranes weigh almost as much as the loads they lift, which means getting them to the job site can be a challenge.
Not only do crane companies need to be experts in the field, they need to be experts in federal and state Department of Transportation requirements for getting equipment to the job site. Even a small company traveling within its own state has to deal with load limits on roads and bridges. They have to know about special vehicle registration, when permits are required, and what permits are required. They need to know when to remove weight from the crane, and how to transport the boom and counterweights separately. Larger companies, traveling over state lines, need to know the subtle differences in requirements from state-to-state or may be faced with large fines, travel delays, or accidents.
Extra planning is required if any part of the travel is off-road or on non-paved roads. The travel plan could call for removing weight from the crane in order to stay within weight requirements on public-paved roads. When going off-road, it may be necessary to use wood, metal or cement matting over the full route of travel, or in extreme cases, building a road that can handle the weight of a crane.
Crane Institute Certification (CIC), recently announced that the mobile crane operator designation, Friction Crane, will be available in 2014. A friction crane is a lattice boom crane that uses clutches and foot brakes for load control instead of a hydraulic system as with modern lattice boom cranes. Friction cranes are no longer manufactured; however, many are still in use on job sites. Since these cranes are still in service and their operation is completely different than their modern counterpart, it is important for accrediting agencies to test operator skills on the crane types they are expected to operate. Read Press Release here.
CIC Currently offers accredited certifications for:
Telescoping Boom Cranes, under 21 tons
Telescoping Boom Cranes, 21-75 tons
Telescoping Boom Cranes, over 75 tons
Lattice Boom Cranes, 1-300 tons
Lattice Boom Cranes, over 300 tons
Articulating Boom Cranes
Qualified Riggers & Signalpersons
For more information about CIC Accredited Certifications, visit: www.CICert.com.
Get prepared with Crane Institute! We offer preparatory classes for taking CIC Written Certification Exams.