Different Types of Cranes
Cranes are machines that use levers and/or pulleys to lift significant weights. A crane one passes on the road may look like a fairly modern invention, but these machines have actually been used for at least the past 2000 years, if not longer. The Romans used cranes to build huge monuments. Medieval churches were constructed with them. Also, the Egyptians may have used them to create pyramids. The modern version can be either simple or complex, and cranes vary based on their application.
A relatively simple crane is the mobile crane. A telescopic boom (arm) or steel truss mounts its movable platform. Either pulleys or levers raise the boom. Generally a hook suspends from the boom.
The platform of a mobile crane can either have traditional wheels, wheels designed for railroad tracks, or a caterpillar track, which is useful for navigating unpaved and uneven surfaces. Mobiles can be used for demolition or earthmoving by replacing the hook with an appropriate tool, such as a wrecking ball or bucket. Telescopic cranes, with a series of hydraulic tubes fit together to form the boom, can also be mobile.
Truck mounted and rough terrain cranes are both essentially mobile as well. The truck-mounted crane generally has outriggers to increase its stability. Rough terrain cranes tend to have a base that resembles the bottom of a 4-wheel drive vehicle. Outriggers also stabilize these cranes. They tend to be used in rough terrain, as the name suggests, and are frequently used to pick up and transport materials.
Loader cranes have hydraulic powered booms fitted onto trailers. They load goods onto the trailer and the jointed sections of the boom are folded down when not in use. The loader may also be considered telescopic, as one section of the boom, in some designs, may telescope for ease of use.
Stacker cranes are most frequently seen in automated warehouses where they tend to follow an automatic retrieval system. For example, in huge automated freezers, these cranes, equipped with forklift apparatus, can work by remote, stacking or obtaining foods as needed. This retrieval system makes it possible to keep workers out of the cold.
