Gears are those circular discs with teeth on them that can be found in almost any moving machine. They’ve been around since the days of Aristotle, and used for a variety of purposes from turn the wheels on your bicycle to generating electricity in large turbines. But how do gears really work? What makes gears such simple, and yet powerful tools?
We need to look no further than the bicycle for answers. Just about everyone is familiar with the concept of a ten speed. Chances are you’ve probably rode on at some point or another. Ten speeds are popular because they allow riders to cover large distances while exerting minimum energy. They do this by allowing the rider to cycle through a system of gears providing different levels of torque. Torque is the force required to move an object. So on our ten speed depending on which gear is engaged, will depend on how hard or soft the rider will have to press on the pedal to move the bicycle.
In other words, gears are used entirely to deal with torque. Small motors can often times spin fast enough to generate the power required to power an object, such as an electric screwdriver even within a car. However, thanks to the laws of physics, a small motor like the one found in electric screwdrivers can not generate the torque needed to drive the screws. Hence the need for gears.
Understanding that gears provide torque is only the beginning of the puzzle. Because depending on the device and the power that device needs to generate, there are no standards for gear fabrication. In other words, to some degree all gears must be custom made to meet the requirements of the job.
Custom gears are necessary for refining the levels of torque required and therefore maximizing the transfer of energy. Again using the bicycle as an example, if a person is attempting to travel uphill, a lower gear ratio needs to be used to generate more torque per rotation of the pedal. Trying to pedal uphill in a high gear ratio would result in a loss of torque and failure to move the bicycle. However, pedaling along a flat surface at high speeds in a low gear ratio would be painfully difficult over long distances. Using a high gear ratio results in less effort and produces the same energy.
Although bicycle manufacturers typically use universal gear sizes and shapes, at their very core bicycle gears are a variation on the custom gears spectrum. When designing a machine that requires the use of gears, engineers must pay particular attention to the torque requirements of the project. Because of the specific needs of each machine it is important engineers are experts in the fields of torque and power conversion.
There are many differences between a bicycle and a car. While both devices are used for transportation they require very different amounts of energy. By using the appropriate gear systems (also known as transmissions) each can easily and effectively accomplish their goal. Gears are amazing devices and it’s a great thing we have them. The next time you drive your car, ride your bike, or even use a cordless drill, say thanks to the brilliant minds that created the gear, making our lives just a little easier.