Comparing three Classes of Levers

All three classes of levers make work easier, but they do so in different ways. In this post, we will discuss a few distinguishing pointers of three types of levers. And, these pointers will help to compare three classes of levers structurally and functionally.

Compare levers belonging to three classes

– In a first-class lever, the fulcrum resides between load and effort. In a second-class lever, load resides between fulcrum and effort. And, in the case of third-class levers, effort resides between load and fulcrum.
Load is also called output, and effort is also known as input.

– When the input and output forces are on opposite sides of the fulcrum, the lever changes the direction of the applied force. This occurs only with a first-class lever.

– When both the input and output forces are on the same side of the fulcrum, the direction of the applied force does not change. This occurs with both the second class lever and the third class lever.

– When the input force is applied farther from the fulcrum, the input distance is greater than the output distance, so the ideal mechanical advantage is greater than 1. This always occurs with second-class levers and may occur with first-class levers.

– When the input force is applied closer to the fulcrum, the input distance is less than the output distance, so the ideal mechanical advantage is less than 1. This always occurs with third-class levers and may occur with first-class levers.

– When both forces are the same distance from the fulcrum, the input distance equals the output distance, so the ideal mechanical advantage equals 1. This is possible only with first class-levers.

Class 1 Lever or first-class lever

Class 2 Lever or second-class lever

Class 3 Lever or third-class lever