Mechanisms

A mechanism is any arrangement of parts that takes one kind of effort and turns it into a useful movement somewhere else. The brake lever on a bicycle, the gears inside a hand whisk, the chain on a chainsaw and the windscreen wiper on a car are all mechanisms. They let a small, convenient input produce a larger force, a faster motion, or movement in a more useful direction. For a designer, understanding mechanisms is the difference between a product that merely looks right and one that actually works.

This note builds the toolkit you need for the 0445 mechanisms objectives: the three classes of lever and the linkages built from them; gears, pulleys, belts, sprockets and chains; the four named types of motion and how mechanisms convert one into another; why friction must be reduced and how lubrication does it; and how the same simple devices let you trade force against distance or redirect a movement entirely. Every idea is worked through with concrete numbers so you can apply it in the exam and on the bench.