History of tower cranes
The history of tower cranes goes back to ancient lifting devices and medieval treadwheel cranes, later evolving with steam power during the Industrial Revolution. The modern tower crane, however, appeared in 1949 when Hans Liebherr created the first self-erecting, mobile tower crane (TK 10) for rebuilding post-war Europe. It featured a rotating tower and a horizontal arm, a design that transformed city skylines and set the standard for high-rise construction. Over time, tower cranes shifted from hydraulic to electric power for greater efficiency.
Different types of tower cranes
By Jib Type (Slewing Style)
- Hammerhead: Horizontal jib with a trolley, strong lifting capacity, commonly used on large construction sites.
- Luffing Jib: Jib that moves up and down, ideal for tight spaces and crowded crane areas.
- Flat Top (Topkit): Horizontal jib without a mast top, allowing cranes to operate close to each other or nearby structures.
By Mobility and Support
- Self-Erecting: Small, easy to transport, and quick to assemble, suitable for low-rise or short-term projects.
- Static (Fixed): Mounted on concrete foundations for long-term, heavy-duty high-rise construction.
- Internal Climbing: Attached to buildings and climbs as floors are added, perfect for skyscrapers.
- Mobile: Mounted on wheels or a chassis for easy movement between sites.
- Rail-Mounted (Travelling): Moves on tracks to cover large site areas efficiently.
By Other Features
- Top-Slewing: Jib rotates at the top of the tower, common for tall building projects.
- Bottom-Slewing: Rotation happens at the base, providing an alternative for stability.
- Braced/Guyed: Supported with guy wires for extra height or stability when needed.
Importance of tower cranes for construction sites
Tower cranes play a crucial role in construction by:
- Maximising vertical reach: Enabling the lifting of materials to great heights, essential for tall buildings.
- Enhancing efficiency: Reducing the need for manual labour and speeding up construction processes.
- Improving safety: Providing stable and controlled lifting operations, minimising the risk of accidents.
- Optimising space: Their fixed nature allows for efficient use of limited ground space on construction sites.
Before committing to a purchase, it’s helpful to check your pre-approved business loan offer to determine the best available funding terms tailored to your business profile.
Key components of a tower crane
Understanding the main components of a tower crane is essential for its operation:
- Base: The foundation that supports the entire crane structure.
- Mast: The vertical section that gives the crane its height.
- Slewing unit: Allows the crane to rotate horizontally.
- Jib: The horizontal arm that carries the load.
- Counter jib: Balances the crane by counteracting the load on the jib.
- Operator's cabin: Where the crane operator controls the lifting operations.
How Tower Cranes Work
- Base: The crane’s base is securely fixed to a concrete foundation or directly to the building structure.
- Operation: The operator controls the crane from a cabin, usually located at the top of the mast.
- Trolley movement: The trolley travels along the jib to position the hook where needed.
- Jib and hook movement: The jib can rotate, the trolley moves sideways along it, and the hook moves up and down.
- Counterweights: These keep the crane stable by balancing the torque from the lifted load, preventing the crane from tipping over.
Specifications of tower cranes
Tower cranes are designed to meet specific construction requirements:
- Load capacity: Varies from 4.4 to 35.3 US tons, depending on the model.
- Jib length: Ranges from 131 to 262 feet, allowing for varying reach.
- Height: Can be extended as construction progresses, accommodating taller structures.
- Rotation: Offers 360-degree rotation for versatile material handling.
- Power source: Available in electric or hybrid models, catering to different site needs.
Parts of a Tower Crane
Core Structural Components
- Base (Foundation): Concrete platform anchoring the crane for stability.
- Mast (Tower): Steel sections providing the crane’s height.
- Slewing Unit: Top part that allows the crane to rotate 360°.
- Turntable: Rotating section that moves the jib.
Upper "Working" Sections
- Jib (Working Arm): Horizontal arm carrying the load.
- Counter-Jib: Rear arm holding machinery and equipment.
- Counterweights: Blocks that balance the load.
- Operator’s Cab: Control station for the crane.
Lifting and Movement Mechanisms
- Trolley: Moves the load along the jib.
- Hoist: Raises and lowers the load.
- Hook Block: Secures the load.
- Wire Rope: Steel cables used for lifting.
Specialised Systems
- Climbing Frame (Top Climber): Enables additional mast sections as the building rises.
- Safety Components: Protect against overload and other hazards.
How a Tower Crane Operates
The working principle of a tower crane is based on balance. The counterweights on the shorter counter-jib are heavier than the maximum load the crane can lift. When a load is raised on the longer jib, both sides balance each other.
The operator controls four main movements:
- Jib rotation: The slewing unit at the top of the mast allows the crane to turn a full 360 degrees.
- Trolley movement: The trolley moves horizontally along the jib to place the load at the right distance from the mast.
- Hook lifting and lowering: A hoist winch system on the counter-jib uses steel cables and pulleys to raise and lower the hook.
- Hook rotation: The hook can rotate, allowing the operator to position the load precisely during movement.
Advantages of tower cranes
Tower cranes offer several benefits:
- High lifting capacity: Capable of lifting heavy loads, essential for large construction projects.
- Extended reach: Their height and jib length allow for lifting materials over long distances.
- Precision: Accurate placement of materials reduces wastage and improves construction quality.
- Cost-effective: Reduces the need for multiple cranes or manual labour, leading to cost savings.
- Safety: Modern tower cranes come equipped with safety features to protect workers and materials.
Safety Features of Tower Crane
Because of the large size of tower cranes, several safety systems are essential to prevent accidents:
- Overload and load moment limiters: These systems track the weight being lifted to make sure it doesn’t exceed the crane’s safe capacity, which could otherwise cause it to tip over.
- Limit switches: These automatically cut power to stop the crane from moving beyond safe limits, such as when the hook reaches its highest point.
- Anemometers: These devices measure wind speed. If the wind becomes too strong, operators must stop work for safety.
- Anti-collision systems: On sites with more than one crane, these systems use sensors and software to detect possible collisions and alert the operators.
Tower crane prices
The cost of tower cranes varies based on type, capacity, and features:
Maximum Lifting Capacity
|
Price Range (Rs. Lakh)
|
Typical Jib Length
|
Crane Type
|
2.5 tons
|
1 – 1.5
|
36 metres
|
Small, self-erecting
|
5 – 6 tons
|
1.6 – 81
|
50 – 60 metres
|
Hammerhead / Flat-top
|
10 – 16 tons
|
11 – 90
|
65 – 70 metres
|
High-capacity, luffing jib
|
20+ tons
|
38 – 111
|
75 – 80 metres
|
Heavy-duty, specialised
|
Prices may fluctuate based on brand, specifications, and market conditions.
Buying guide for a tower crane
When purchasing a tower crane, consider the following:
- Project requirements: Assess the height and weight of materials to be lifted.
- Site conditions: Evaluate space availability and ground stability.
- Crane specifications: Match the crane's capacity and reach with your needs.
- Budget: Determine the total cost, including installation and maintenance.
- Manufacturer reputation: Choose reputable brands known for quality and reliability.
For financing options, explore equipment machinery loan to support your purchase.
Tower crane financing options
Financing a tower crane can ease the financial burden:
- Equipment loans: Obtain loans specifically for purchasing machinery.
- Leasing: Lease options allow for crane use without ownership.
- Instalment plans: Spread the cost over time with manageable payments.
- Government schemes: Explore subsidies or incentives for construction equipment.
Consider consulting with financial institutions to find the best financing solution for your needs. One option you can consider is our industry equipment finance.
Conclusion
Tower cranes are vital for modern construction, offering high lifting capacities, extended reach, and operational efficiency. Understanding their types, components, and financing options, like a business loan, can help you make informed decisions for your construction projects. Whether purchasing or leasing, ensure the chosen crane meets your specific requirements and budget.
Helpful resources and tips for business loan borrowers
