Gears: The gear is a wheel with teeth on it’s perimeter, which can fit next to another gear and at a 45 degree (or right angle). By turning one gear, any gear connected to it will move as well. By using that technology, you can use less force to turn things that are very hard to move by hand. Gears are used in many modern inventions such as cars, motorcycles, bikes and clocks.
Cams: Cams are a wheel with a hole in it, with a shaft, and a follower attached to the shaft and crank connected to the cam. A water wheel with a cam attached to a huge hammer, it can be powerful enough to smash iron. This can reduce labor force because it is more effective than a man pounding a piece of iron with a hammer because it takes more muscle to smash it with a hammer than to use a cam and water wheel. Cams are very useful inventions.
That was a little what I learned on simple machines. I hope you learned something too.