It is not an understatement to say that cranes are the backbone of construction. Just as crucial as the crane is the crane operator, who works the crane alongside the rigging crew for safe and efficient movements.
Everyone on the construction site, from safety managers and directors to manufacturing and construction workers, should know the different types of cranes and their uses. Using the right crane for the job can enhance safety and prevent resource wastage.
Static Cranes vs. Mobile Cranes
There are two types of cranes used in construction — static and mobile. A static crane is fixed to a position in the workplace and lifts and moves objects along a predetermined path. Mobile cranes can move from one site to another while mounted on wheels or treads.
Static cranes are typically permanent or semi-permanent structures attached to a roof, the side of a building, or anchored to the ground. They can lift and carry a load to different areas or other sites. Mobile cranes may require on-site assembly, outriggers for transporting up high rises, or counterweights for heavy loads.
Regardless of the type of crane, regular crane inspections are crucial for OSHA regulatory compliance, safety enhancement, and better resale value.
Different Types of Static Cranes
Static crane types typically must be assembled at the workplace in a fixed spot. While this feature restricts their mobility, it allows them to lift heavier loads higher. They remain in place until the project is complete.
Here are the different types of static cranes used in construction:
1. Tower Cranes
A tower crane, recognizable by its vertical, tower-like structure and horizontally outstretched jib, assists in constructing tall buildings like skyscrapers. The hook block and trolley move along the jib, which rotates 360 degrees on the mast.
Tower cranes come in three variations:
- Self-erecting tower cranes: These cranes can fold and unfold, allowing for on-site assembly and transportation. Their mast is mounted to a ballast and includes a horizontal jib. Compared to other tower cranes, their frame is lighter and carries a lower maximum load.
- Hammerhead tower cranes: These cranes rest on a fixed tower with a horizontal, rotating lever. They feature a trolley along the forward-extending arm, counterbalanced by a weight on the back-extending part of the arm. Raking allows the trolley to move back and forth along its arm.
- Luffing tower cranes: These cranes share a similar design to hammerhead cranes but differ in their ability to raise and lower the jib. This feature allows them to lift heavier loads and function better in congested work environments.
2. Overhead Cranes
An overhead crane, or bridge crane, features a horizontal beam, or bridge, that travels along a track between two additional horizontal beams. A-frame legs or a track along the inside of a building support them. These cranes are commonly used to load and offload cargo at ports, construction sites, or industrial facilities.
Overhead cranes have two variants:
- Jib crane: This type of overhead crane has a moveable hoist attached to a jib mounted to a wall or pillar. It is a permanent fixture installed over a workstation that operates repetitive tasks.
- Gantry crane: This variant of the overhead crane features two a-frame legs usually fixed to a track, allowing the crane to move along an outdoor path.
At first glance, overhead cranes can seem straightforward. The hoist carries the load, lifting it from the pickup point and moving it horizontally along the bridge beam. The simplistic visage of overhead cranes can cause operators to overlook critical operational elements, resulting in failure, accidents, or damage.
3. Level-Luffing Cranes
A level-luffing crane keeps its hook in the same position relative to its base while luffing, or moving up and down. It moves its horse-head jib up and in or down and out, driving the hook forward or backward horizontally to maintain its level. This type of crane is vital when you need to move loads carefully near ground level. They can also rotate 360 degrees.
Different Types of Mobile Cranes
Mobile cranes offer more versatility than static cranes. They are mounted on or built into a vehicle with wheels or tread, allowing them to move around or between sites.
Here are the different types of mobile cranes used in construction:
1. Crawler Cranes
Crawler cranes are mobile, robust, and convenient. They do not require outriggers, making working on unprepared worksites easy. The crane is mounted onto a caterpillar track. Their unique structure provides superior strength and mobility, making them the ideal option for hefty loads.
Crawler cranes are commonly used when construction projects are starting because they work well with freshly torn-up ground. Their large size and treads allow them to move freely over marshy, soft, and rough terrain. Their broad base prevents them from sinking during a lift.
2. Truck Cranes
Truck cranes are attached to a truck bed or chassis — standard or customized. They can travel on roads and move from one site to another without assembling anything. Outriggers and counterweights offer stability and allow them to lift heavier loads while moving slowly. They are identified by their telescopic boom, which reveals a base and mast structure that is separate from the outrigger system.
Different types of truck cranes offer heavier lifting capacity and reach, making them useful for maintenance, inspection, and bridge-building. Examples include boom trucks, truck-mounted cranes, hydraulic truck cranes, and articulating boom trucks.
3. Rough Terrain Cranes
Rough terrain cranes are vehicle-mounted cranes that operate on uneven terrain. They have an undercarriage with four off-road tires and extending outriggers to maintain their level and stability while hoisting a load. These features make them ideal for construction sites covered in rocks or loose dirt.
These cranes are usually light and small, using one engine to power their telescoping boom and undercarriage. That makes them more effective for carrying and moving lighter loads in tight spaces and around a site. However, they can not travel fast or on paved roads and must be transported to a site.
4. All-Terrain Cranes
All-terrain cranes allow you to carry and move loads on rough or paved terrain. These cranes have an extra engine compared to rough terrain cranes to help power their longer telescoping boom, outriggers, and up to 18 extra wheels. These additional features and a wider cab make all-terrain cranes heavier, meaning outriggers are necessary for lifting loads.
An all-terrain crane can handle heavier loads than rough terrain cranes but struggle in tight spaces. It can travel on public roads but may require some assembly on-site.
5. Carry Deck Cranes
Carry deck cranes are the smallest construction cranes. They are typically used to move smaller objects within a site. The design comprises a simple four-wheel deck holding a 360-degree rotating mounted crane.
These cranes carry loads on their deck, offering versatility but limiting their maximum capacity. Their small size and hydraulic controls allow them to navigate tight spaces and operate with precision.
Choosing the Right Crane for the Job
Cranes are essential at almost every construction site, as most jobs require lifting and moving heavy materials. Having the right people to operate them properly and safely is also crucial. That means having a rigger, signal person, and operator.
Unlike signalers and riggers, OSHA requires crane operators to undergo training and carry certifications. Many states also mandate that they have a license to operate mobile cranes. Consider tailored crane operator training for your team. Certified crane operators have the knowledge to select the right crane for particular job specifications, enhancing project success and company reputation.
