Choosing the right crane for a particular project involves careful consideration of numerous factors. In addition to meeting the required lifting capacity requirements, various other logistical elements may influence selection, including crane configuration, site access, lifting plans, and site safety. Each individual site must be thoroughly assessed prior to crane selection to ensure that lifts will be done safely, effectively, and economically.
Appropriate crane selection may initially seem like a daunting task due to the vast number of crane options available. However, each crane is designed for a specific function or use; therefore, the key to selecting the right crane lies in assessing the requirements of the particular lifting job.
Some of the crane characteristics that need to be considered include, but are not limited to:
- Crane lifting capacity
- Crane configuration and dimensions
- Site conditions
- On-site obstacles
- Lifting distances
Factors to Consider When Choosing a Crane
Crane selection involves significant planning and preliminary preparation. Failure to assess the various factors that affect lifting can result in the selection of an inappropriate crane, which can negatively impact project schedule and budget.
One of the most influential factors in determining the right crane for the job is the job site. First, the chosen crane needs to be able to access the site in question. For example, is there enough space to accommodate the selected crane’s dimensions? While a boom truck may be ideal for paved roads and driveways, it may be restricted in areas where the access is relatively narrow.
Additionally, once on the site, the soil bearing capacity must be capable of adequately supporting the weight of the chosen crane and its foundation. Geotechnical analyses may need to be done to ensure that the weight of the crane and its load does not exceed the bearing capacity. Other factors that might significantly influence the crane size, type, and configuration include:
- Terrain roughness
- Obstructions (power lines, buildings, etc.)
- Weather conditions
- Traffic restrictions
In addition, not all cranes are built for large outdoor jobs. Smaller fixed indoor and outdoor cranes are used in a wide range of industrial settings to move bulky objects. For example, they may be used for assembling oversized components in large manufacturing projects, loading furnaces and transporting hot metal in foundries, or assisting with disassembly and reassembly of systems during maintenance operations. Indoor cranes have their own set of pre-selection criteria, including:
- Crane operation speed requirements
- The distance materials must be moved
- Maintenance requirements
- Service conditions
- Obstacles
The physical properties of the load to be lifted must also be carefully analyzed when choosing the right crane for a particular lifting job. Cranes have different specifications regarding capacity and functionality. Load charts provide essential details, such as boom lengths and rated capacities, which will help outline the gross weight, height, distance, and radius that a given crane can safely handle. Proper use of manufacturer-specified load charts will help avoid selecting a crane with too little capacity and can prevent catastrophic events such as crane toppling.
Choosing the Right Crane for Your Project
Listed below is a brief overview of several types of cranes and their primary functions and features. Understanding the dynamics of each crane type is essential in determining which equipment is best suited for a particular application.
- Mobile hydraulic cranes
These cranes are among the most versatile available. They can be quickly mobilized and removed from a site and occupy considerably less space than other types of cranes. However, mobile cranes tend to be more expensive than lattice boom cranes.
- Tower cranes
Tower cranes are relatively tall structures that are fixed to the ground on a concrete slab or foundation. Tower cranes offer the best balance between height and lifting capacity and are typically used in the construction of tall buildings. These cranes, however, require skilled operators due to stricter safety requirements.
- Crawler cranes
Crawler cranes are a type of mobile crane mounted on crawler tracks. They are available with either telescopic or lattice booms and are capable of lifting extremely heavy loads (80 to 825 tons). Crawler cranes are best suited for longer-term projects due to their bulkiness and time-consuming assembly and disassembly processes.
- Overhead traveling bridge cranes
Overhead cranes are typically used in indoor industrial environments. They consist of a pair of parallel runways with a traveling girder or bridge which spans the gap. A trolley, which is mounted on the bridge, controls the movement of the hoist and hook. Overhead cranes are typically used in manufacturing or maintenance applications to move loads through a facility’s available overhead space.
- Gantry cranes
Gantry cranes offer an alternative to overhead cranes and are typically used as an outdoor solution. The main difference between gantry cranes and overhead cranes ae the rigid steel legs which allow them to be used outdoors. Gantry cranes usually span a maximum of 150 feet and are capable of load capacities up to 150 tons.
- Jib cranes
Jib cranes consists of a horizontal arm mounted on a vertical support such as a mast or tower. These are the most common types of cranes and can be either mobile or stationary. The main drawback of jib cranes is their limited coverage area.
- Monorail cranes
Monorail cranes boast similarities to overhead traveling bridge cranes, except the hoist and trolley run on a single stationary girder. Monorails tend to be more versatile due to their ability to maneuver around complex floor spaces.
Frequency of Use
Frequency of crane use also plays a part in equipment selection and is referred to as the duty cycle. While some cranes are ideal for occasional use, they may not be suitable for continuous or heavy duty usage. Cranes are therefore classified by their duty cycle. A summary of these classifications is shown below:
- Class A: Standby or Infrequent Service
- Class B: Light Service
- Class C: Moderate Service
- Class D: Heavy Service
- Class E: Severe Service
- Class F: Continuous Severe Service
Crane selection requires careful, early-stage planning and analysis of several lifting requirements. It is also essential to have an in-depth understanding of the features and benefits of the different types of possible crane choices. For more information about crane selection, please visit the sources below.
Resources
- The 6 Overhead Crane Classes: What You Need to Know
- Selecting The Right Overhead Crane
- Recommendations on Overhead Crane Selecting
- Instructions for the Preparation of Crane Information – Navfac
- Selecting a Tower Crane
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