Have you ever stopped to think about the various kinds of cranes used in numerous industries? According to the civil engineering resource hub The Constructor, 12 types of cranes are used for all kinds of purposes, from erecting skyscrapers to excavating raw materials at mines. Tower cranes and lattice boom cranes (crawlers) are among the most widely used types because of their numerous applications.
Ready to learn all about the uses, build structure, and safety protocols of these mammoth machines? Let’s begin.
Tower Cranes
Structure
As the name suggests, tower cranes are used to lift raw materials like steel beams and concrete cinder blocks while building tall structures such as skyscrapers. According to engineering experts, there are two main kinds of tower cranes: horizontal (or saddle-boom) cranes and luffing boom cranes.
Horizontal tower cranes have a simple ‘T-shaped’ structure; they feature booms attached to masts that are held in position using kent ledges. A counterweight is attached to the tail end of the boom to keep it stable, and the other end is used to lift loads. Ropes are attached from the top of the mast to either side of the boom for additional stability, and a saddle is located near the center of the boom to maneuver the crane.
Luffing boom cranes have a structure that resembles a fishing rod. The mast is secured on a foundation, and a boom is attached to a turntable at the top with a counterweight on its tail for stability. This structure allows the boom to rotate easily. Luffing boom cranes get their name from the word ‘luff,’ which means to move the crane jib up and down to lift a load.
Uses
Horizontal and luffing boom tower cranes are used to construct tall buildings. These cranes feature tall masts to lift materials like glass panes and steel beams into position. They’re typically found in cities like Seattle, Los Angeles, and New York City, where booming populations have caused a spike in demand for high-rises in recent years.
Luffing boom cranes feature booms that operate diagonally to the mast. This gives them a smaller footprint than tower cranes in which booms are perpendicular to the mast. As a result, luffing boom cranes are used in tighter construction spaces, such as building sites in between pre-existing skyscrapers.
Safety Protocols
According to the Occupational Safety and Health Administration, tower cranes must be equipped with the following safety devices:
Anti-two block crane alarm to prevent the boom tip from colliding with the load block/ball/hook
Load moment indicators to prevent overloading and keep the crane stable during operations
Hoist drum lower limiters to prevent the hoist cable from being spooled completely
Radius indicators to prevent horizontal tower cranes from crashing into other buildings/cranes around them
Jib stops to prevent the jibs on luffing boom cranes from damaging things around it
Lattice Boom Cranes
Structure
As the name suggests, lattice boom cranes feature booms made using 3-dimensional webs of metal with triangular patterns known as lattices. Lattice boom cranes are ideal for lifting exceptionally heavy loads because of the substantial strength-to-weight ratio of lattice structures.
According to a diagram adapted from the Construction Safety Association of Ontario, lattice boom cranes have four main components: a turntable mounted to treads, a lattice boom, a jib, and hoists/blocks. The turntable features a counterweight that prevents the crane from tipping over should it pick up a heavy load. A back hitch and gantry keep the lattice boom and jib stable, while a jib heel is used for additional maneuverability.
Uses
Lattice boom cranes were originally used to construct buildings until mobile, all-terrain tower cranes with telescoping booms became popular, as per a study published by the American Society of Civil Engineers.
Nowadays, lattice boom cranes are primarily found at mining sites where cranes are primarily used to move heavy loads as opposed to elevating them to a certain height. Their use at mines and quarries is one of the main reasons lattice boom cranes are mounted to massive treads that enable them to traverse soft-ground terrains such as mud, snow, and gravel.
Safety Protocols
The Occupational Safety and Health Administration has made it mandatory for lattice boom crane manufacturers to equip these massive machines with many safety devices. These include:
Load moment indicators to keep the crane from tipping during operations
Anti two block switch that stop the crane from being damaged as a result of the ball, load, or hook smashing into the boom tip
Boom hoist limiters to prevent the crane from hoisting dangerously large loads
Boom angle and radius indicators to help crane operators judge the angle at which the boom and jib are being maneuvered
Summary of the Differences Between Tower and Lattice Boom Cranes
The primary difference between tower and lattice boom cranes is where they’re used, which has a lot to do with their structure. Tower cranes are used in high-rise construction sites because they’re designed to lift materials to massive heights, while lattice boom cranes feature a lower center of gravity, making them stable and of great use on soft-ground sites.
Crane Warning Systems Atlanta Provides Load Moment Indicators to Help Tower and Lattice Boom Crane Operators Comply with Safety Regulations
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