Questions and Decisions
Engineers start with the wheels!
Wheels must:
- support the pushcart and the driver
- stay on the road
- stay attached to the axle in all conditions
- spin freely
- steer the pushcart
- meet the specifications for the challenge
Suggestions and Choices
You will need to think about:
- materials - what sort of wheels should you get?
- specifications - what are my limitations?
- number - can you have two different pairs of wheels or must all four be the same?
- attachment - how you will fix your wheels to your frame?
- tools - where will you find the tools you need?
- skills - can you learn the skills you will need?
The best wheels will have good friction with the road surface when stopping and turning ('road holding' capacity).
The best wheels will have very little friction with the road when travelling in a straight line.
The best wheels will rotate freely without friction at the 'hub'. This is usually achieved by using bushes (sleeves) or bearings.
The best wheels will keep your centre of gravity as low as possible.
To stop your pushcart the wheels must stop rotating. This causes friction between the wheel surface and the road.
Try This
For each type of wheel you have available you should list the choices you have. Write down the 'strengths and weaknesses' (PDF 14KB/2 pages) for each choice to help you make your final decision.
Test your wheel option for:
- ease of attachment
- strength
- durability
- road-holding capacity
- safety for working with it
- safety for broken pieces
For Teachers
Wheels can be purchased from many hardware suppliers. By typing 'wheels' into the Yellow Pages you will be directed to all sorts of options.
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