There are many types of custom gears, but custom bevel gears have been used in important inventions throughout history, making possible varied machines from the simple water-powered gristmill to the printing press to the space shuttle. But what exactly is a bevel gear, and how has it developed today?
Bevel Gears 101
A gear, also called a cogwheel, is a circular piece that has “teeth” sticking up from it. When these teeth mesh with other pieces, it allows for torque to be transmitted through the mechanical system. The shafts of bevel gears are mounted on an angle—typically perpendicular from each other, so that one shaft is vertical and the other is horizontal. In straight bevel gears, the teeth are, as the name implies, straight. An improved design, spiral gear teeth are curved and set on an angle so that the gear engages gradually.
Bevel Gears in History
To see a clear example of how bevel gears work, visit an old-fashioned gristmill or look at videos and pictures of one online. The water wheel on the outside of the building turns on a horizontal axis due to the flow of the water. But the stone inside needs to turn on a vertical axis in order to grind whatever is being milled. The direction is converted using large examples of early bevel gears. The gear ratio (how many teeth there are on each gear) even allows the inside parts to rotate more rapidly than the outside ones, so the stone can turn faster and grind a greater volume material more quickly.
Bevel Gears Today
Gear manufacturing methods have become much more advanced in the 20th and 21st centuries. Cast iron is still a popular material used for custom gears because of its durability, but the gear manufacturing process allows for greater precision in gear cutting, which in turn leads to more efficient energy transfer. These carefully engineered bevel gears are important in many machines and engines used every day, including everything from hand drills to high-performance cars.