Essential Facts About Construction Crane Types and Operations

1. Types of Construction Cranes

Construction sites utilize various types of cranes for lifting and positioning heavy materials:

• Light Crane
• Derrick Crane
• Crawler Crane
• Port Crane
• Climbing Crane
• Cable Crane (Blondin)
• Telescopic Crane
• Tower Crane

Other Lifting Equipment

In addition to cranes, other lifting machinery includes:

• Forklift
• Cargo Lifts
• Forklifts

2. Tower Crane Mechanics and Components

The tower crane comprises a vertical mast and a horizontal jib (beam trusses). A trolley slides along the jib for loading. The structure is formed by the mast (shaft) and the counter-jib (countershaft).

It can be fixed (mounted on a cross chassis or embedded in a concrete mass) or mobile (running on rails with an end stop).

A tower crane can measure up to 75 meters tall and have a jib length of 40 meters.

It utilizes a powerful group of four electric motors:

• One for translation (movement along the rail).
• One for slewing (guiding the jib rotation).
• One for trolley displacement (driving the wagon).
• One for elevation (raising and lowering the load).

Each motor usually has a rotation limiter and travel limit switches.

3. Main Electric Motor Functions

The primary actions performed by the tower crane motors are:

• Slewing (Orientation of the jib/rotation)
• Trolley Displacement (Distribution/Movement of the bogie)
• Elevation (Raising and lowering the load)
• Translation (Movement of the entire crane structure)

4. What is Tower Crane Telescoping?

When erecting the crane, if we need to increase the height of the mast (shaft), we use a telescopic system. This process involves lifting the upper section (which holds the hook) vertically using hydraulic cylinders, creating a space where a new mast section can be inserted into the structure.

5. Derrick Crane Specifications

The Derrick crane consists of a vertical mast held by two rigid braces. It utilizes two pulleys: one drives the cable for raising and lowering the boom, and the other is for lifting loads. The slewing motion is controlled by the base belt, limited by the two braces.

This type of crane can lift over 400 tons and typically has a boom length of 20 meters.

6. Dismantling a Tower Crane

A telescopic crane is typically used for dismantling. The tower crane is often disassembled into larger sections than those used during assembly (i.e., several sections together). This method is preferred because it is more cost-effective to dismantle the larger components on the ground rather than on the crane itself.

The most common removal process sequence is:

1. Counterweights
2. Jib (Arrow)
3. Counter-Jib (Against arrow)
4. Jib, Cabin, and Mast sections
5. Slewing Ring/Neck (removed in installments)
6. Support Base

7. The Blondin (Cable Crane) System

The Blondin is a specialized type of cable crane, often used in the construction of dams or bridges. It is designed to span wide valleys or large gaps. The system involves placing a tower (pole) on each side of the span, with a cable running between them on which a trolley (wagon) travels.

There are four main structural variants:

• Fixed Tower system
• One fixed tower and one tower capable of tilting up to 20 degrees to both sides
• One fixed tower and one tower capable of moving in a semicircle
• Two movable towers

8. Safety Protocols for Fixed Cranes in Urban Areas

When operating a fixed crane, especially in sensitive locations like the Old Town of Granada, specific safety standards must be met:

• Ensure no accumulation of people beneath the operational area.
• Avoid making oblique turns (sudden or diagonal movements).
• Ensure the crane is rated for the prevailing wind conditions.
• Implement ongoing maintenance schedules.
• Verify interlock wiring is functional.
• When operations cease for the day, leave the crane out of service (in free slewing mode).
• Prevent accidental maneuvering of the control keypad.
• Establish a clear project location plan if multiple cranes are operating simultaneously.