Here, a set of different gears like Spur gear, Bevel gear, Helical gear, Rack & Pinion, Worm & Wheel are fixed in the frame. Operate each of the gear set and observe the direction of rotation and speed of each gear.

The science behind it :
Each gear is designed for a different purpose to transmit the torque from one axis to another, except for Rack & Pinion. In the Rack & Pinion arrangement, the torque is converted to linear force by meshing the Rack with Pinion.