- Most freight elevators use the exact same control system as passenger elevators. The elevator rides up and down in a vertical track. It is attached to a winch, powered by an electric motor. The other end of the cable is attached to a counterweight, which weighs about as much as the elevator does when it is half-full. The electric motor turns, unrolling or re-rolling the cable to raise or lower the elevator. The control system also has built-in brakes to slow the rate of descent.
- Like passenger elevators, freight elevators have safety features to prevent serious accidents. Some have multiple cables so that, if one snaps, the elevator will continue to work. If somehow all the cables fail, the elevator has a spring-loaded catch at the top. If the elevator starts to fall, the catch will shoot rods out on either side, locking into the track and preventing the elevator from moving. Finally, the elevator has a giant shock absorber at the bottom to stop it from impacting forcefully against the bottom of the shaft if it does plummet.
- Electric elevators are quick and efficient, but aren't powerful enough to lift the heaviest freight. Heavy-duty freight elevators use hydraulics instead. The elevator platform is on top of a piston plunger. To raise the platform, a powerful motor pumps oil into the piston, pushing out the plunger and moving the floor up with it. To lower the elevator, the fluid is slowly released from the plunger again. This system is slow and energy intensive, but it is powerful enough to lift planes on aircraft carriers.
