Electrical contacts in tower cranes help build cities

Self-erecting tower cranes are a critical component in the rise of modern skyscrapers. They grow along with the high-rise they’re helping to build, either beside it or in the center. The tower crane not only constructs the building it also assembles itself. And of course, when the building has reached its final height, the cranes simply reverse the process.

Tower cranes from Liebherr, Orlaco, Wolffkran, Linden Comansa, Rnomac, and others all work in a similar fashion. The temporary installation of tower cranes starts months in advance. A large concrete base is poured which will eventually anchor the crane. Then when construction begins, the crane is assembled by a smaller portable crane until the tower base and mast rise into the air along with the slewing arm. Once the first few mast pieces are put together and the arm and counter weights are added, the crane can then add to its own height via the climbing assembly. It then builds itself higher along with the edifice it’s constructing.

How does the crane lift itself and various building materials?

Using large and small motors the tower crane lowers its winch cable where riggers attach the cable to various components. A motor engages, powering the winch and lifting the load. Once raised to the desired height the load can then be moved along the slewing arm by another motor. And of course the crane top can usually swivel or rotate as well, often powered by another motor.

Typically tower cranes utilize AC motors, though DC motors are also used. The preference for AC power stems mostly from the readily available source at most construction sites and some other basic advantages of AC power for this application.

It’s electrical contactors that are starting and stopping tower crane motors

Similar to gantry cranes, found in port facilities, the motors in tower cranes generally involve the use of multi-pole electrical contacts. Contactors offer the ability to handle higher voltages and offer safety advantages. And again, the variety of cranes and crane manufacturers means you’ll find a wide variety of motors and motor control systems that source their electrical contacts from leading OEMs (e.g., ABB, Siemens, Eaton, GE and others).

Where you find electrical contactors you’ll find Repco replacement contacts too

Most tower cranes are rented for the duration of a construction project. Then they’re disassembled and moved. The cost to install and dismantle a tower crane runs around $60,000 along with a monthly rental fee of $15,000 per month. Combine this with rigid construction schedules, that can incur delay penalties, and the seriousness of keeping your crane operational is doubly important.