Examples of first-class levers include a balance scale, a seesaw and a crowbar. A first-class lever places the fulcrum in the middle of the effort and the load.
Three classes of levers exist: first-class, second-class and third-class levers. The position of the fulcrum, load and effort determine the class of lever. A second-class lever places the load between the effort and the fulcrum. An example of a second-class lever is a wheelbarrow. Third-class levers place the effort between the load and the fulcrum. A hammer driving a nail and the human forearm when it is used to lift an object are examples of third-class levers.