Class 2 Lever at the mouth of the Nene

 

This gate is by the lighthouse that Peter Scott lived in during the 1930s and which was the inspiration for The Snow Goose by Paul Gallico. There is a twin lighthouse on the far bank. The gate is worked by a long arm. The effort is applied to the top and the load is the force of the compression spring holding the bolt in place. It is a Class 2 lever because the load is between the pivot and the effort. By the Principle of Moments, Effort x d2 = Load x d1. Since d2 is roughly twice d1, the effort is roughly half the force you'd need to apply to pull the bolt directly.