Rack and pinion gear systems involve the use of a round gear called a pinion and a flat gear called a rack. A simple model of this type of gear system is shown below. Using the same or similar gear modelling kit, set up the arrangement of gears shown in the photographs.

1. Put the back board and base in position.

2. Add the pinion (round gear) and rotate by hand.

3. Add the ‘gauge’ above the pinion. This will be used later to measure how far the gear moves. Check the pinion can still rotate.

4. Add the ‘rack’ (flat gear) so that it meshes with the pinion. Check the pinion can still rotate.

If the pinion revolves in a clockwise direction which way does the rack move? (Left or right).

 

If the pinion revolves in a anticlockwise direction which way does the rack move? (Left or right).

Using the ‘gauge’ - if the pinion moves three teeth, how many teeth does the rack move?

5. Explain one use of a rack and pinion gear system. Draw a diagram to help explain your answer. (click here for example)

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