Cranes have been used for millennia to lift heavy loads. They have been used in shipping and in construction. These days, cranes are still used in shipping and construction. Without them, container ships wouldn't be easily loaded or unloaded and the tallest buildings in the world wouldn't exist. But how do cranes really work?

Simple Machines

Cranes take advantage of different simple machines. Simple machines are things like levers, pulleys, wheels, and screws. These simple machines are force multipliers. That means that they take the force that is put into them and greatly multiply it so that the resulting force is much larger than the incoming force. This force multiplication is what can allow a man to lift an engine out of a car using a set of pulleys. Cranes specifically use levers and pulleys. 

Levers

A basic lever is a rigid rod that is set on a fulcrum. On one side of the fulcrum is the weight to be lifted, on the other is the counterbalance which allows the weight to be lifted, while still staying in balance. In most crane set up, the cab acts as the fulcrum. There is a counterweight or counterbalance set behind the cab which allows for the heavy weights to be lifted and keeps the crane from tipping over while the lift is happening. 

Pulleys

A pulley is a wheel that is on a rod or axle with a cable or belt that runs along it. As the rope of belt is pulled, the pulley spins. The moving pulley maximizes and multiplies the force put into it. The more pulleys in any given system, the heavier the weight that can be lifted with the same or lesser effort. In a crane, the pulleys are set up so that the crane can lift the load without putting stress on the crane arm. The stress of lifting heavy weights without the pulley system could bend the crane arm, damaging it, or even cause the crane to tip, since it would end up being pulled out of balance. The heavier the load that the crane is expected to lift, and the higher the lift, the more pulleys the system will need to have. 

Without those simple machines, a crane wouldn't be able to work. Without a crane, shipping would be much harder because the heavy loads wouldn't be able to be switched from ship to train easily, and construction of tall buildings wouldn't be practical. For more information, talk to a professional like Craneology INC.