How Construction Cranes Work

Cranes are a fixture in any construction site. They are very easy to spot because they rise hundreds of feet up in the air. Basically, they help a construction crew carry building materials. This includes steel and concrete as well as heavy tools like acetylene torches and generators.

How Construction Cranes Work

Parts of a Construction Crane

Construction cranes are also called tower cranes. They have three main components:

  1. The base, which is fixed to the ground on a concrete slab.
  2. The mast, which is the supporting tower of the crane. Attached to the base and made of steel trussed sections, the mast gives the crane its height and is assembled during installation.
  3. The slewing unit on top of the mast is the engine that makes the crane rotate.

The slewing unit has three parts:

Long horizontal jib – This is the working arm of the crane that carries the load. A trolley slides across the jib to move the load horizontally. The lifting hook attached to the jib is controlled by the crane operator using a system of electric motors and wire rope cables.

Shorter counter-jib – This carries blocks of concrete to serve as counter weight while the jib suspends the load to and from the center of the crane.

Operator’s cabin – This is where the crane operator sits and where all the electronic controls are located.

In cases where the crane is remote controlled from a ground radio, there is no need for an operator.

How Much Weight Can a Crane Lift?

The maximum load that a typical construction crane can lift is 18 metric tons or 39,690 pounds. The crane cannot support the maximum load if it is positioned at the end of the jib. The closer the load is to the mast, the more weight the crane can lift.

Most construction cranes have the following specifications:

  • Maximum unsupported height – 265 feet (80 meters)
  • Maximum reach – 230 feet (70 meters)
  • Maximum lift weight – 19.8 tons (18 metric tons), 300 tonne-meters
  • Counterweights – 20 tons (16.3 metric tons)

What Keeps Cranes Upright?

Construction cranes do not have any wire support, yet they can withstand strong winds even at ridiculous heights. How is that possible?

The base of the crane is made of solid concrete measuring 30 feet by 30 feet by 4 feet and weighing around 400,000 pounds (182,000 kg). The crew pours concrete into this slab several weeks before the crane arrives. Large anchor bolts are embedded deep into the concrete slab to ensure the stability of the crane.

How Do Cranes Grow?

Cranes are transported to the construction site via trailer rigs. To assemble the crane, the mast is built one section at a time.

Here are the steps to growing a crane:

  • Hang a weight on the jib to balance the counterweight.
  • Detach the slewing unit from the top of the mast.
  • Hydraulic rams push the slewing unit up 20 feet in the top climber.
  • A mobile crane lifts another 20-foot mast section into the gap opened by the climbing frame.
  • Once bolted in place, the crane is 20 feet taller.
  • When the project is finished, the crane comes down in a reverse process.

Renting a Construction Crane

Equipment rental companies offer full crane services for a fee. This includes delivering the crane to the job location and assembling the parts. They will charge a monthly rental fee while the crane is on the site. Contact your reliable construction equipment rental company to ask for a quote.

Written by Lindsey Rentals. Lindsey Rentals offers the best equipment rentals in Columbia, MO.

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