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Tower Crane Dismantling Derrick Now Available in North America
Enlarge Image A tower section lowered to street as the derrick dismantles the 355 HC-L luffing tower crane.
September 22, 2009 – Dismantling tower cranes from tall buildings is no simple task, but Liebherr’s 200 DR 5/10 derrick crane is designed specifically for the challenge. This summer, Salem, Ore.-based Morrow Equipment introduced the crane to the North American market and leased it to Sellen Construction in Seattle, Wash.
The construction company used the all-electric derrick to dismantle a Liebherr 355 HC-L luffing tower crane at 1918 Eighth Avenue, a 36-story commercial office tower project in downtown Seattle. The Liebherr 200 DR 5/10 delivers an 82-foot reach and a 22,000-pound lift capacity. It is equipped with frequency-controlled, stepless drives for all movements: slewing, luffing and hoisting. Movements are monitored with a PLC control system. Lifting height, load moment, boom incline, and swing gear are all monitored and backed up with sensors. The derrick operator, using the remote control handset, can operate the crane from any position to his or her advantage.
Enlarge Image Liebherr derrick crane mounted on top of an office tower in Seattle.
Scott Amick, Sellen’s senior project engineer, noted the Liebherr derrick had the right combination of a small footprint and lift capacity for the job. “Using this derrick helped us to avoid other craning options that would have involved a three-week street closure as well as blocked parking access,” Amick said. “Since the tower crane involved a unique removal sequence, we planned for extra days in case of possible delays. It worked out that the derrick was erected on Monday and in full use by midday Tuesday.”
Once the tower crane was removed, the derrick topped-off the project setting the remaining structural steel, HVAC equipment, and roofing materials.
Enlarge Image The 200DR 5/10 boom installation facilitated by a tower crane on the project.
Derrick dismantlement was also quick. No other crane was needed to disassemble the 200 DR 5/10. It breaks down into easy-to-handle components that fit into the jobsite construction hoist for removal.
Morrow and Sellen worked side-by-side on this phase of the office tower project. “Morrow engineers and technicians provided critical layout and sequencing input throughout the entire planning process,” Amick said. “They were on-site during the derrick installation, use, and dismantlement providing support.”
