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Gear investigation: Banbao Lego crane








Completion date: May 16, 2020

1. Gear ratio: 8:24:40. The bottom wheel cranking the string at speed (8/24)*(24/40)=0.2x speed of the motor.
2. The top two wheels looks like pulley system to me, but I am not sure about the spinning speed of the top wheels, the first top wheel is slower than the bottom wheeler, that I observed.
3. The beginning of the bottom wheeling action is pulling less string because the circumference is small (less string winded).  So it pulls the string faster gradually as more string is added to the circumference.
4. Note I added the rewind crank on the other side of the motor.

This is the final instruction of the Banbao booklet. All the builds have been fun for me, I got to know more about gears now (though still primitive).

My thoughts towards the gear mechanism is that it is not as efficient as I thought it would be.
- requires many gears to do 1 simple thing
- gear design has to match the many requirements of the space, distance, speed...while selecting the right number of teeth, size of teeth, size of gear are critical to the overall design of the product (e.g. dimension) and have to be taken into account. I feel there are so many constrains. The gears have to be so customised. It doesn’t sound cost effective.
- there is cable connection to utilise to solve the distance problem.
- gears are good/efficient in changing rotation directions, and to different rotation planes.

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