For EPC contractors and construction project teams, selecting a tower crane is not simply a matter of choosing the model with the highest rated tonnage. The real challenge is ensuring that the required load can be lifted at the necessary working radius, hook height and crane configuration throughout the project.
Tower crane capacity must be evaluated against the actual lifting requirement, not just the maximum capacity stated in a product brochure. A crane capable of lifting a heavy load close to its tower may have a substantially lower rated capacity at the far end of its jib. This difference can affect crane selection, material-flow planning, project costs and the feasibility of critical lifts.
For experienced project teams, the most useful approach is to assess the manufacturer's load chart alongside the project's lifting schedule, building geometry and site constraints. This guide explains how to make that assessment, compare configurations and prepare the technical information needed to evaluate a tower crane for purchase or rental.
When evaluating tower crane capacity, three figures deserve particular attention: maximum rated capacity, capacity at the required working radius and tip load. These figures describe different aspects of the crane's rated performance and should not be treated as interchangeable.
Maximum rated capacity is the highest load permitted under the specified operating conditions and configuration. It does not represent the capacity available at every point along the jib.
Capacity at the required working radius is the rated load available at the horizontal reach needed for the actual lift. This is often the more useful figure when assessing whether a crane can handle the project's demanding lifting operations.
Tip load generally refers to the rated capacity at the outer end of the jib or at the manufacturer's specified maximum-radius position. The exact definition should be confirmed in the relevant technical documentation.
Consider a project that requires heavy precast components to be placed near the edge of a building. A crane with a high maximum capacity may still be unsuitable if its rated capacity at that placement radius is insufficient.
The selection process should therefore begin with the heaviest planned loads and their lifting positions, then identify the crane configurations that satisfy those requirements.
Working radius is one of the most important parameters when comparing tower crane configurations. It represents the horizontal distance from the crane's slewing axis to the load's lifting position, as defined by the manufacturer's documentation.
For conventional tower crane configurations, the available rated lifting capacity generally decreases as working radius increases. The exact relationship depends on the model and configuration, so the manufacturer's rated load chart must be used.
For project planners, this has a direct practical implication: the crane must be assessed at the positions where the required loads will actually be handled.
A useful assessment considers:
Checking only the maximum load at a short radius can leave a project team with a crane that cannot meet its requirements at the required reach.
this reason, a tower crane capacity assessment should be based on the project's lifting schedule and layout rather than on a single headline capacity figure.
A tower crane load chart provides the manufacturer's rated lifting capacities for specified operating conditions and configurations. It is the reference document for checking whether a proposed lift falls within the crane's permitted limits.
Experienced buyers should request the applicable technical documentation for the exact crane model and configuration being considered.
Use the following process to evaluate the chart.
Identify the heaviest planned load and obtain reliable weight information. Include the relevant lifting accessories in accordance with the manufacturer's rated-load conventions and the approved lifting plan.
Use the project layout to identify where the load must be picked up and placed. Assess the required reach for the planned lifting operation rather than relying solely on the building's overall dimensions.
Verify the jib length, reeving arrangement and other configuration details that determine which rated load chart applies.
Locate the applicable value using the manufacturer's instructions. If the chart specifies different operating configurations or restrictions, confirm that the selected entry corresponds to the proposed arrangement.
Verify that the load and lifting arrangement remain within the permitted capacity and operating limits. A capacity check is only one part of the complete lifting assessment.
If the chart, configuration or proposed lift is unclear, obtain confirmation from the manufacturer or a qualified lifting professional before finalising the selection.
A generic chart or a specification from a similar-looking crane is not an adequate substitute for the documentation applicable to the actual equipment.
Suppose an EPC contractor needs to place a precast component weighing 3 tonnes at a working radius of 35 metres.
The project team should first verify the complete load assessment, establish the required radius and identify the proposed crane configuration. It can then consult the manufacturer's load chart to determine the rated capacity permitted at that radius.
If the applicable chart permits a load of 3 tonnes or more under those conditions, the capacity check may be satisfied, subject to all other restrictions and the approved lifting plan.
If the permitted capacity is below 3 tonnes, the proposed configuration does not meet the stated requirement. The team must reassess the crane selection or lifting arrangement through the appropriate technical process.
This example illustrates the decision process only. It does not represent an Orange Machine Tech product specification or establish that any particular crane can perform the lift.
The important takeaway: Tower crane load chart calculation is a model- and configuration-specific verification exercise. A universal formula or maximum-tonnage figure cannot replace the manufacturer's rated capacity data.
Working radius is not the only consideration when evaluating tower crane capacity. The crane must also provide the reach and configuration required by the project.
The required jib length depends on the area the crane must serve, including material delivery points and planned lifting positions. A longer jib may provide the necessary reach, but its rated capacity must still be checked against the proposed configuration.
The crane must provide sufficient hook height for the planned lifts and site geometry. Building height, the intended lifting operations, tower configuration and applicable tie arrangements should be considered during technical planning.
The approved reeving arrangement and other manufacturer-specified configuration parameters may affect the applicable rated capacity. Buyers should compare the complete technical configuration rather than assume that cranes with similar maximum tonnage have equivalent performance.
Foundation and anchorage requirements, access for erection equipment, nearby structures, operating restrictions and wind limitations can affect the feasibility of the proposed crane arrangement.
These requirements should be assessed alongside the load chart. A crane that appears suitable on capacity alone may not be appropriate for the project's complete site conditions.
Before requesting a purchase or rental quotation, prepare the following information. It helps suppliers evaluate the application and identify the technical details that need clarification.
This information gives the supplier a clearer basis for assessing the proposed crane configuration. It also reduces the risk of comparing quotations that use different technical assumptions or include different scopes of supply. For more information check the tower crane selection guide.
Once the lifting requirements and suitable configurations have been established, the next decision is whether to purchase or rent the equipment.
Purchase may be worth evaluating when expected utilisation across projects supports ownership and the contractor can account for maintenance, deployment, storage and long-term equipment requirements.
Rental may be more appropriate for project-specific requirements, limited-duration work or situations where the contractor wants to avoid a long-term ownership commitment.
The commercial comparison should include more than the quoted equipment price. Review the scope of mobilisation, erection and dismantling, maintenance responsibilities, breakdown support, project duration and any configuration changes required during the job.
Most importantly, compare options that satisfy the same technical requirements. A lower quotation is not a meaningful saving if the proposed configuration cannot meet the required lifting capacity or reach.
Orange Machine Tech offers tower cranes for sale and rent. Contractors can share their project requirements to discuss suitable equipment options.
Compare the manufacturer's rated capacity at the working radii required by the project, along with jib length, hook height and configuration. Maximum rated capacity alone does not establish that two cranes are equally suitable.
Tower crane load capacity depends on the specified operating conditions and working radius. Tip load generally refers to the rated capacity at the outer end of the jib or the manufacturer's designated maximum-radius position. Confirm the terminology in the relevant technical documentation.
Not necessarily. Maximum rated capacity may only be available under specified conditions and at a shorter radius. The manufacturer's load chart determines the permitted capacity at the required working position.
Provide the load schedule, required working radii, hook height, site layout, installation constraints, project duration and purchase or rental preference. These details help the supplier assess a suitable configuration.
No. The crane must meet the actual lifting, reach, site and programme requirements. A higher maximum capacity does not automatically provide the required capacity at the working radius or make the configuration more suitable.
Selecting the right tower crane requires a clear understanding of the project's loads, working radii, required hook height and site constraints. Evaluating these requirements against the manufacturer's rated load chart provides a stronger technical basis for comparing equipment options.
If you are planning a construction project, share your lifting requirements with Orange Machine Tech to discuss tower cranes for sale or rent.
Prepare these details before enquiring : heaviest planned load, working radius, required hook height, site location and project duration.
