gear type 1 (driven and driving gear)

if you want more power and less speed, you have the driving gear as the bigger one, and the driven gear as the smaller one. and vice versa.

gear type 2 (crown gears)

this is my crown gear, a crown gear changes the direction of motion by 90 degrees.

gear type 3 (worm gears)

almost the same as crown gear but in a gear box.

gear type 4 (sliding gear)

almost the same as a gun/slinger/slingshot if smaller.