I have developed this gearbox for a client who is working in partnership with a power generation company and wishes to promote renewable energy information.The gearbox uses extremely cheap PVC gears available from http://www.rapidonline.com/ and http://www.mutr.co.uk/ which come as a set of three gears to push fit onto a 3mm shaft and a pinion gear to push fit onto a standard 2mm electric motor shaft. I came up with the idea because the gearboxes already available needed a lot of parts and used fairly small gears, and cost a lot. As regular readers will know, bringing costs down to schools is essential as then projects can be individual or small group and be integreated into the regular SOW of a school.
The front and back plates are manufactured on a laser, but can also be made on a router using a 2mm cutter. The bolts holding it together are standard M4 ones, and the motor used as a power generator is a standard large size solar motor (http://www.mutr.co.uk/) .
It can be built with three combinations of gears giving ratios between 1:3 and 1:14 approx. These arc easily changed in about 3 minutes.
The total cost in parts to a school is about £2 and having fairly chunky gears with big teeth, it is robust. The longer plate, on the production version, is designed to be cut in 3mm plywood so that the gearbox can be screwed to a pole and then stuck in the ground for testing.
The client and I will be offering this design to a manufacturer to produce a kit in bulk. It is hoped that many schools can then benefit from this project.
