Hydraulic cranes work using the concept of transmitting a force from one point to another through a fluid. Fluids, especially liquids, play a vital role in hydraulics because of their mechanical properties such as how they move, how they react to pressure and how they resist movement.
The basic principle of a hydraulic system is that a force applied at one point is transmitted to another point through an incompressible fluid, according to How Stuff Works. This basic principle of hydraulics is widely used in engineering to move things.
Although air can also be used in hydraulic systems, liquids are preferred in systems that move heavy loads because they are incompressible. This means that if pressure is applied to the liquid, its volume does not change.
All hydraulic cranes use the basic principle of hydraulics to work. However, there are usually various components involved in lifting a heavy load. The basic components are the jib, hook, outriggers, rotex gear, counterweights and reinforced steel cable.
The steel boom is the most recognizable part of a hydraulic crane and acts as the arm that lifts the load. The outriggers provide the crane with support, while the rotex gear allows the cab to swivel and move the boom. A hydraulic arm extends and retracts to raise or lower the boom.