Understanding the Center of Gravity to a Mobile Crane
With mobile cranes, there are three basic components that has individual center of gravity points. We have the Superstructure, carrier and boom. Each of these components have their own center of gravity. Depending on how each piece lays they can affect the others center of gravity. Let’s breakdown each component and see what it does.
The superstructure also known as the upper structure is the revolving frame which holds the operators cab. Usually the upper structure supports the counter weights on rear, then the boom and/or other attachments on the front. With this component, no matter the position of the crane the center of gravity will always remain the same.
The carrier also known as the carbody is the under carriage of the crane. Dependent on the type the carrier usually holds the carrier cab, wheels/tracks, outriggers, etc. It is manufactured for transporting the superstructure. Unlike the superstructure where the center of gravity will always remain the same. The center of gravity will vary on the carrier. This is reliant on the location of the direction of the boom. For example, when the boom is over the rear axles the center of gravity will be forward of the rear axles. If the boom is perpendicular to the carrier the center of gravity will be center of the carrier’s width.
The last component to keep in mind is the boom. Just like the other components it as well has a center of gravity to keep in mind. The center of gravity can be affected depending if you are increasing or decreasing the length of the boom. Unless, one is using a lattice boom in the case of this the center of gravity will remain the same until a jib or other ancillary items is added.
The boom is a common suspect to tipping accidents. Let me explain, when we apply boom angles. As the boom raises or lowers through an arc, the booms center of gravity is moves towards or away from the tipping axis. When the movement of a hydraulic boom is combined with the movement through the arc, we have encouraged a tipping accident.
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Part 3: Mobile Crane Stability – Taking the Crane Apart. (2017, October 30). Retrieved from CraneTech