How Do Different Kinds of Gears Work?

Steel shafts

Gears are used in many different mechanical devices, and perform many important jobs. The most important purpose they serve is providing a gear reduction in motorized equipment, which provides a small motor with enough torque for a device, as well as power. There are different kinds of gears, that operate in different ways.

  • Spur Gears – Spur gears are the most common type of gears. They have straight teeth mounted on parallel shafts. Spur gears are used in many machines, such as washing machines and clothes dryers, but their main disadvantage is that they are very loud. Each time a gear tooth engages a tooth on the other gear, the teeth collide, and this impact makes a noise, and also increases the stress on the gear teeth.
  • Helical Gears – The teeth on helical gears are cut at an angle to the face of the gear, so when two teeth engage, contact starts at one end of the tooth and gradually spreads as the gears rotate. This gradual engagement makes helical gears operate much more smoothly and quietly than spur gears. For this reason, helical gears are used in almost all car transmissions.
  • Bevel Gears – Bevel gears are useful when the direction of the shaft’s rotation needs to be changed. They are usually mounted on shafts at 90 degrees apart, but will work at other angles as well. Bevel gear teeth can be straight, spiral, or hypoid.
  • Worm Gears – Worm gears are used when large gear reductions are needed. In worm gear systems, the worm can easily turn the gear, but the gear cannot turn the worm. This feature is useful for machines such as conveyor systems, in which the locking feature can act as a brake for the conveyor when the motor is not turning.
  • Rack and Pinion Gears – Rack and pinion gears are used to convert rotation into linear motion. One common example of this is the steering system in many cars. The steering wheel rotates a gear which engages the rack. As the gear turns, it slides the rack either to the right or the left, depending on which way you turn the wheel.

Gears are a simply technology, but they are found in machinery all over the world. By all accounts, there are several machines in the very room you are sitting in, which require all kinds of gears. Learn more.