Other Technical Articles

Auro Parts Technical Articles

Home >> Technical Articles >> Basic Type of Cranes
Basic Type of Cranes
Time: 2018-02-04
Cranes are applied for lifting and placing such things as heavy steel beams, pre-stressed concrete sections for buildings or bridges, materials and supplies to the upper stories of a high rise, unloading trucks, and a host of other essential jobsite material handling tasks.
 
*Truck Mounted Crane
 
Truck mounted cranes sit on a commercial truck chassis. The truck engine is used to power the crane operation. Telescopic boom models perform the same functions as their all terrain and truck crane siblings although they are limited to ratings of about 40 tons, the limitation imposed by the commercial truck chassis itself. These cranes may come with fixed operator control stations and cost less than an all terrain crane or truck crane.  
 
 
There are models where the cab swings with the crane. Another variation is an articulating boom unit; usually these are specialized horizontal boom units designed to load/unload the truck's payload. They are normally not used as general-purpose cranes. Lattice boom truck crane models offer high lifting capacities and hook heights and are designed to handle the big lifting jobs. By their nature, lattice boom cranes require more setup time than hydraulic boom models.
 
Truck cranes can travel safely at highway speeds. They use purpose-built carriers with separate cabs for the carrier and crane operations. The hydraulic boom units are designed for quick setup. The smaller and mid-range models generally carry boom, jib and counterweight on board. Some of the larger units may require separate transport arrangements to carry any additional counterweights or boom extensions.
 
Truck mounted cranes are not as agile on rough underfoot conditions and shouldn't be taken onto undeveloped job sites unless there are good roads and work platforms. Capacity for these machines exceeds 100 tons. There are some cranes that can reach heights over 200 feet when rigged with a jib.
 
*Rough Terrain Cranes
 
Rough terrain cranes remain king of the job site. They handle tough off-road conditions with four-wheel drive and with various types of steering for maneuverability. They are simple — a two-axle configuration and have only one cab from which the operator controls all functions.
 
This kind of cranes is relatively inexpensive in comparison to other types of cranes. Since they don't have to travel at highway speeds, they don't require the horsepower or drive train components. The two-axle configuration is another major cost saver.
 
Their biggest drawback comes from the fact that they have to be transported between jobs. Once on the job, they excel at pick-and-carry operations. They are a sound economic investment for a contractor who does a lot of lifting on the job. Construction is moving more and more in the direction of "complete or nearly complete" components as part of the building process. Poured in place structures and tilt-up panels are only a couple of examples. Typical units on job sites range from 30 tons to 70 tons with the largest unit in regular production having a 100-ton capacity. Today boom tip height will exceed 150 feet, and jib tip height will reach beyond 200 feet. Again, with every show there are new cranes that constantly change the spec charts.
 
*All Terrain Crane
 
All terrain cranes have become a very popular construction tool. They offer the highway travel speeds of the truck crane and share off-road characteristics with rough terrain cranes.
 
Multiple axles — steer drive and tag — distribute the load. Multiple driven axles provide traction to handle tough jobsite conditions, and multi-axle steering provides added maneuverability. There are suspension options that can provide added off-road clearance and enhance driving characteristics, making a crane that is easy to take on the road from job to job no matter how far the trek.
 
All terrains have been moving into areas traditionally held by truck-mounted and rough terrain cranes, pushing both just a little. Capacity on these machines can reach 1,000 tons. Jib tip heights can be measured at over 600 feet and boom heights at 400 feet (plus or minus).
 
*Lattice Boom Crane
 
Lattice boom cranes are both truck-mounted and crawler-mounted. With truck-mounted cranes, the crane's upper structure is mounted on a truck-style carrier, which can travel at highway speeds.
 
Major sections of the crane usually have to be removed and transported separately on some of the larger units. The advantage over crawler cranes, which must be disassembled, is that the carrier is mobile and erection time is usually faster.
 
Crawler-mounted cranes are mounted on car bodies and are propelled on tracks. This design yields superior on-site mobility and lifting capacities. Crawler cranes are not easily transported and require considerable setup time. All of the modular components of a crawler crane have to be moved by trucks. Crawler cranes do offer a great deal of versatility, particularly for heavy lifts or long-term lifting projects. From pick-and-carry capabilities to heavy duty or severe duty applications, such as pile driving and dragline, crawler cranes offer a great deal of application versatility.
 
Choosing a specific crane is typically based on job requirements. A lattice crane is typically the best choice when the job requires long, vertical reaches, significantly large lifts, or long-term work. Both truck and crawler-mounted lattice boom cranes are well adapted for lifting and moving large quantities of steel, constructing large tilt-up concrete panels, and for making very high and far-reaching picks. The design of lattice booms is inherently stronger and more stable at greater distances than telescopic boom cranes, plus lattice boom cranes utilize larger-diameter wire rope, requiring fewer parts of line for faster line speeds. Typically, a lattice crane yields higher capacity picks at a nominal base capacity unit, making a 100-ton capacity lattice crane outperform a 200-ton capacity telescopic crane.
 
The hydraulic-crawler-mounted crane is the latest innovation in crane design and technology. It's available as a telescopic or lattice boom crane mounted on a crawler excavator carrier and offers yet more versatility in your choice of lifting device.
 
In the final analysis, determining which crane to use for which job comes down to the same parameter we apply to any equipment selection: What is the application? For cranes, the main application considerations are how high do you have to lift the load, how far out must it be placed and what does it weigh? The bulk of the load can also be a factor in that a bulky load may require a larger crane to handle physical dimensions in order to obtain lift height required at a given radius. Other considerations include the terrain and if the crane will be working on- or off-road, pick-and-carry considerations, single or repetitive lifts, travel time and distance, and other factors. Cost considerations also enter into the equation and will be viewed differently depending on the end user.
 
 
 
Source: www.constructionequipment.com