Capital Equipment News July 2018

TOWER CRANES

Liebherr's fast-erecting crane’s jib can distribute the loads all over the jobsite without disturbing site activities.

crane is completely self-erecting, and additional hoist equipment is not needed. In contrast, the conventional tower crane always requires a mobile crane. Depending on the possibility of positioning the mobile crane on the building site, the size of the respective mobile crane is one of the biggest cost drivers of a crane erection,” explains Maier. Apart from the mobile crane, Maier adds that one also needs significantly more skilled crane fitters/technicians when using a top slewing crane. “A fast-erecting crane is usually set up with only two skilled workers, whereby the installation time is one hour to half a day (depending on crane size),” he says. “A large fast-erecting crane like a Liebherr 81K.1 is usually repositioned within one day (dismantling, transportation to the new site and erection). For a top-slewing crane you often need four to five skilled workers over about two days plus the mobile crane with the operator. In addition, the fast- erecting crane can generally be set up from the ground,” says Maier. Another advantage is the simple logistics. The fast-erecting crane forms a complete unit with all of its necessary components. Only a few accessories have to be brought to the building site,

and dismounted in tight space conditions. With a top-slewing crane, generally additional space is required for the mobile crane and a lot of space must be taken into account for the pre-assembly of the jib and counter-jib. This requires good planning,” says Maier. Maier adds that a fast-erecting crane is a fitting solution for small building sites with short project periods. “On small building sites, telescopic handlers, all terrain cranes or excavators are often used as lifting equipment. These systems require considerably more time and space to move material on the building site,” he says. The same view is shared by Terry, who says that self-erecting tower cranes are designed for small projects and their compact design limits ground preparation requirements, adding that

for example, counter ballast. “Therefore, you can’t forget anything. With the top- slewing crane, all components must be distributed on several trucks and have to arrive in the right order on the building site, to ensure that the assembly works without any problems. Often, however, there is only little space to park the trucks at the building site,” he says. Addressing space constraints Speaking about space, Maier says the space requirement for a fast-erecting crane in operation is comparable to that of a top-slewing crane. However, the big advantage, is that during installation, only the space for the crane in transport position is required (small footprint). “Using the jib assembly in the air, fast-erecting cranes can be also mounted

“A large fast-erecting crane like a Liebherr 81K.1 is usually repositioned within one day (dismantling, transportation to the new site, and erection). For a top-slewing crane you often need four to five skilled workers over about two days plus the mobile crane with the operator. In addition, the fast-erecting crane can generally be set up from the ground.”

CAPITAL EQUIPMENT NEWS JULY 2018 8