This short guide introduces the various gears, how they work, and their common uses.

Without gears, walking around is hardly that easy. These engineering components can be called the silent heroes of our daily lives, because when they conduct business inside the machines, these machines receive all the honors for their hard work.

This is a brief overview of the various types of gears and their uses, suitable for any novice engineer out there, or anyone who wants to learn their knowledge and start using gears-both literally and figuratively.
Spur gears are one of the most common gear types. They have a cylindrical pitch surface and belong to parallel axis gear sets. Their tooth lines are straight and parallel to the shaft.
Spur gears are commonly used because they can be produced relatively easily while achieving high-performance accuracy. The larger of the meshing pairs is called the gear (as shown in the figure above) and the smaller is called the pinion. They are commonly used to increase or decrease the torque in machines such as washing machines, dryers, screwdrivers, clockwork alarms, and blenders.
Similar to spur gears, helical gears are used with parallel shafts. They are also cylindrical gears with winding teeth. However, they have a certain improvement over spur gears in design. Unlike spur gears, the leading edges of the teeth on helical gears are not parallel to the axis of rotation, but at a certain angle.
This smooth tooth meshing means that the gear can transmit higher loads and is quieter than the spur gear, which may produce noise at higher speeds. When these gears generate thrust in the axial direction, thrust bearings are required. They are used in elevators and other machines and factory automation.
The appearance of the bevel gear is conical and the top has been cut off. In the bevel gear series, there are several different subsets, including spiral bevel gears, straight bevel gears, spiral bevel gears and bevel bevel gears.
Bevel gears are used to transmit force between two shafts that intersect at a specific point. They are used in differential drives, such as those in turning cars, because they can transmit power to two axles that rotate at different speeds.
Spiral bevel gears are bevel gears with curved tooth lines. Compared to spur gears, helical gears are similar to helical gears, and their curvature allows a higher tooth contact ratio, which means that spiral bevel gears are more efficient than standard bevel gears; they are stronger, have less noise, and have less vibration.

Why can’t the standard bevel gear you require completely replace the spiral bevel gear? Spiral bevel gears are more difficult to produce, and in some applications, they also generate unnecessary thrust in the axial direction due to the curved teeth.
The “worm” of a worm gear refers to a thread shape cut into a shaft, and a matching gear or worm gear is fixed on the shaft. Due to the sliding contact of the gear surface, hard materials are usually used for the worm to reduce friction. Although sliding contact means that worm wheels are not efficient, their rotation is very smooth and quiet. Therefore, they are commonly used in industrial applications, heavy equipment, and sometimes consumer products.
Worm gear reducers have a high reduction ratio and are usually self-locking because they cannot run in the reverse direction. This inherent function makes it a safe choice for use in certain types of machinery. A common example of a self-locking worm gear is the machine tuning head found in many stringed instruments, including guitars.
Crown gear, also known as reverse gear, is a bevel gear whose teeth extend at right angles to the plane of the wheel. This makes the tooth resemble the tip of a crown and gives the gear a name. Unlike bevel gears, crown gears are cylindrical. Depending on the design of the teeth, they can be paired with other bevel gears or spur gears.
Crown gears are usually used where low noise gears are required. The crown gear used with the rack interlocking wood rod allows the gear to roll with the rack, even if it must go uphill or sideways. They are used for trains on uphill tracks, roller coasters, door locks on tracks and car steering wheels.
We may not need to tell you why we call the sun and planetary gears that way. Its simulated orbital flywheel movement allows the sun gear and planetary gears to convert reciprocating motion into rotational motion. This is why James Watt used it in his early steam engines.
In the picture above, the sun is yellow, the planets are red, the reciprocating arm is blue, the flywheel is green, and the drive shaft is gray. The sun gear and planetary gears are an example of planetary gears or planetary gears in which the center of one gear rotates around the center of the other gear. They are used for everything from pencil sharpeners to locomotive engines.