Category Archives: Mechanical
This project is similar to the 4WD car, not only in that the student is working with wood and electrics, but also that the concept of drive ratios is involved. The crane takes this a little further: one can observe how the winch diameter affects lifting speed and power, and the very useful principle of mechanical advantage gained by the two pulleys. When this is taught in schools, it is normally not easy for kids to really get it as a concept; how the addition of pulleys increases the lifting power and reduces the speed. More often than not they only wind up memorizing formulas so they can pass the test and forget about it. But by making and playing with one themselves, they can see first-hand what actually happens when you add pulleys. They no longer need to memorize anything – they just know it.
This is also a lot of fun to play with. Continue reading
This project gives some familiarity with electricity, motors and wiring. It also gets a child thinking about drive methods, gears/pulleys and their ratios, since the wheels are obviously turning much slower than the motor, power to the wheels being geared down in two stages. Another principle is that of friction and how rubber around the wheels results in more traction. All of these principles can be raised for discussion and further investigation if it seems appropriate for the student’s level. Continue reading