Learn more about Cranes

Frequently Asked Questions

Equipment types

What is a mobile crane?


A mobile crane is a crane that has tires for traveling and is nearly completely assembled or easily ready for work. Types of mobile cranes: Advantages: Can drive directly on the road. Minimal truckloads of additional equipment or none all together lower cost of mobilization. Quick setup time and quick dissemble Disadvantages: Load chart is not as strong (300 Ton AT can lift much less than a 300 ton crawler) Need to setup crane at each location even if only moving a small distance. Cannot travel with a load on the hook Difficult to fit in tight places Difficult to maneuver on site with rougher surfaces All mobile cranes use outriggers to stabilize themselves while lifting. Some Rough Terrain cranes can lift a much smaller amount without setting up outriggers, stabilizing on their tires only. All Terrain cranes (ATs or hydros) can be driven legally on the road directly to the job site. Keep in mind that permits and other preparations must be made in order to do this. Hydraulic cranes are truck mounted cranes with a hydraulic expandable(often rotating) boom. These cranes are versatile and flexible as they cantravel on the road independently and require limited or no assembly onsite. Load capacity is relatively limited (ranging from 8 - 1200 tons) and inprinciple no movement of the crane with a load in the hook is possible,with exception of the Rough Terrain (RT) crane. Rough Terrain cranes (RT’s) and Carry decks (CD’s) cannot be driven on the road as they have much larger tires and cannot travel as fast. These cranes are often trucked to the jobsite.




What is a crawler crane?​


Crawler cranes are cranes that do not have tires but instead use tracks to travel. These cranes are trucked to the jobsite and are often in many different pieces when trucked due to their weight and size. Crawler cranes have tracks instead of wheels and have a boom consisting
of several sections (often lattice structured steel frames). Crawler cranes are
usually assembled on site and composition (boom length) can be adjusted
to specific requirements. A back-mast can be fitted to the crane. This
provides additional lifting capacity. In general, crawler cranes have higher
lifting capacity and can move around with loads in the hook. These cranes
are usually stronger than hydraulic cranes and can carry loads ranging from
80 - 1600 tons. However, latest designs for crawler cranes go up to a lifting
capacity of 3000 tons.




What is a rough terrain crane?


Advantage: Minimal truckloads of additional equipment or none all together lower cost of mobilization. Quick setup time and quick dissemble Can travel with a load on the hook with very light objects) Can fit in tight places Can handle rougher surfaces Disadvantage: Cannot drive directly on the road require a truck to ship it. Load chart is not as strong (100 Ton RT can lift much less than a 100 ton crawler) Need to setup crane at each location even if only moving a small distance.




What is the difference between the main boom and jib?


The main boom for an AT (All-terrain mobile crane) is the large telescopic portion that is usually attached to the crane. A jib is an additional piece to the main boom that can be added or could already be attached but stowed away by folding on the side of the main boom. In both cases the jib extends from the end of the main boom and is usually at a different angle than the main boom which gives the crane additional reach without interfering with obstructions to the main boom.




What is the difference between a fly-jib and luffing jib?


A fly jib is typically a smaller jib and it is fixed at a given angle relative to the main boom. A luffing jib is typically larger than a fly jib and its angle can be adjusted during operation.





Size and costs

What determines the size of the crane I need for my project?


The size of a crane is dependent on many factors, most importantly: Weight of the load Distance from crane center to load set position (max radius) After this information is known, other details are to be determined. Here are a few questions that are important to ask: Will the crane fit in the desired location? Am I lifting over any obstructions? What is the size of the load? Will it interfere with the crane boom while lifting? Do I have enough room to assemble the crane? These are just a few examples of minor details that can have a huge impact on the crane size, and subsequently the cost of a solution. There are many other factors not mentioned that may need to be taken into account. Always consult a Mammoet expert to be sure you have the right crane for your job!




Which factors influence the cost of the equipment?


The size of the crane Mobilization of the crane (amount of truckloads) How far will it have to travel Permits and government regulations A short duration job would require a mobile crane it is quick and efficient. A long duration on a rough site would require a RT. A long duration with many lifts would be ideal for a crawler.





Ground Bearing Capacity

What is ground bearing pressure?


Ground bearing pressure is the load exerted on the ground by the points that contact the ground. It is a force over an area known as PSF or pounds per square foot. An allowable ground bearing pressure is the amount that the ground can handle without causing any long-term damage or collapse. This is important for cranes because if the ground fails then the lift is no longer stable. Therefore at eavh point of contact with the ground loadspreaders are used to decrease the ground bearing pressure. This create a more stable lift and a safer job.




What are loadspreaders?


Loadspreaders are any piece of equipment that increases the area on a point of contact. They can be a variety of shapes an sizes, but the most common are rectangular or circular. Common load spreaders: Wooden crane mats Steel load spreaders Steel plates Laminated mats Synthetic mats





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