Doosan Heavy Industries & Construction, a South Korean contractor based in Changwon, utilized Manitowoc's MLC650 crawler crane to carry out heavy lifting operations at a congested railway station work site. Situated in Daegu City, 300 km from Seoul, the station is part of an expansion project being managed by the South Korean government's rail department.
Bearing in mind the site's limited land area, it offered little space for large cranes to operate, let alone the additional buffer required for assembly and dismantling. Despite these challenges, the MLC650 was still able to lift heavy objects such as 55 t pre-cast concrete sections and move them to designated areas with precision.
The MLC650's ability to navigate with ease in highly congested job sites, coupled with its increased capacity for heavy lifts without traditional counterweight configurations, can be credited to its unique Variable Position Counterweight (VPC) technology. The system allows for reduced ground preparation, lower space requirements and counterweight; and eliminates the need to stack or unstack counterweights after or during a lift.
For the railway station job, the MLC650 was configured using a 68 m main boom with the VPC-MAX attachment, a special configuration that uses VPC technology to offer improved capacity and reach. In this set-up, the crane was used to service a load of 62 t, positioning it at a radius of 50 m. This was still possible despite local site stipulations requiring that the crane lift at only 70 percent of its rated capacity.
The closest alternative choice of crane for this project required a small hill – 10 m x 10 m x 40 m – to be levelled in order for it to be positioned, and this location was also a further 10 m away from the site. Such a distance also immediately translated to a 25 percent decrease in load capacity. In contrast, the unique and compact design of the MLC650 allowed it to be stationed comfortably adjacent to the railway.
"This feat accomplished by our advanced MLC650 crawler crane is a testament not just to the company's longstanding reputation for engineering ingenuity but its real world relevance in modern congested work sites, particularly in urbanized environments like South Korea," said Choi Byung Eun, president and CEO of Shinui Petra, the rental company that owns the crane. "We always aim to provide unmatched value to our customers and that has been clearly evidently in this project."
Following the completion of lifting operations at the Daegu railway site in April, the MLC650 was immediately moved to another work site: a cement factory. Over a period of three months, its role will be to support the removal and replacement of equipment parts to refurbish the factory's processing machines.
Similarly, one key operating challenge was the factory's narrow space. The MLC650 was chosen again for its ability to take maximum advantage of ground bearing pressure at close proximity. A more extensive configuration comprising a 50 m main boom with VPC-MAX and an added 47 m luffing jib was deployed, showcasing the MLC650's versatility.