Gears are a very interesting devices.  First of all they can transfer energy  from one place to another.  They can also add to the energy to make many more times its power.   For example a multi-speed bike: you are going up a big hill and you are not tired.  The reason for this is the bike's gears are transferring your energy and multiplying it to make more energy than you are actually putting in.  On a  bikes gears the higher the gear the more energy you are using, the lower the gear the less energy you are using to make more power. 

The force of the Ferris Wheel's motor and the gears are pulling this first car up in the air.   As the motor pulls the car up and the gravity pulls it down, the hinge that connects the car to the wheel lets it stay straight and move freely so it will not tip over.   The force of gravity and the motor pull the car to the beginning of the Ferris Wheel and the brake will pull the car to a stop for the next passenger.