When an operator is in control of every element of a heavy lifting operation, it’s a breeze to manipulate complex machinery and awkward loads. All three planes of axial movement can be managed with singular fluency, moving the focus of the lifting operation with linear efficiency. There are few rules to limit these monstrous assemblies, but one would be the sphere of operation, the range of coverage. Another rule, perhaps the most obvious one, is load capacity.
It’s logical to assume the initial rule is constricted by a rectangular space, one that’s governed by three dimensions of movement, but engineering practices rapidly took this line of thought apart. Modern cranes are on wheels, on pedestals and on the backs of trucks, mobilizing the burdens they carry. Still, there are certain profiles of cranes that stick to the rectangular space. Take a look at the overhead crane, an internalized crane that runs on rails, chains, and oily-smooth reduction gears to run from one end of a warehouse or garage to the other. The traditional overhead crane on a framework of metal stanchions and girders is the constant companion of garage workers and packaging departments. The fixed arrangement is designed to carry small to medium loads to every corner of an open room, and external models do exactly the same task, loading and unloading cargo.
The mobile crane is the next entry to consider. This breed of lifter has taken the construction world by storm. The light to extremely heavy capacity lifting attributes of crane trucks comes from simple flatbed trucks retrofitted with knuckle boom cranes, but the heavier models are dedicated machines, heavy plant vehicles with one cabin for mobilization and a separate cabin used only for controlling the boom. Outriggers stabilize the chassis of the truck during heavy lift operations and remove the wheels a fraction of an inch from the ground. Meanwhile, returning to the low-profile cousins in the crane truck family, articulating arms fold away after low-capacity lifts to streamline the truck.
Let’s finish up with the grandfather of all cranes, the pedestal and tower form. Hundreds of feet tall, tower cranes are frameworks of latticed steel constructed in a mast and jib shape. Driven by multiple motors, these cranes rotate and lift multiple tons of steel and concrete up to the top of the next generation of skyscrapers, the massive engineering projects currently shaping the modern world.
