Gears certainly are a crucial component of many motors and devices. Gears assist in torque output by giving gear reduction and they adjust the spiral bevel helical gearbox direction of rotation just like the shaft to the rear wheels of automotive vehicles. Here are some fundamental types of gears and how they are different from each other.
Spur gears are mounted in series on parallel shafts to attain large gear reductions.
The most typical gears are spur gears and so are used in series for huge gear reductions. One’s teeth on spur gears are straight and are mounted in parallel on different shafts. Spur gears are found in washers, screwdrivers, windup alarm clocks, and other devices. They are particularly loud, due to the equipment tooth engaging and colliding. Each effect makes loud noises and causes vibration, which is why spur gears aren’t found in machinery like vehicles. A normal equipment ratio range is 1:1 to 6:1.
Helical 
gears operate more smoothly and quietly compared to spur gears due to the way one’s teeth interact. The teeth on a helical gear cut at an angle to the face of the gear. When two of the teeth begin to engage, the contact is gradual–beginning at one end of the tooth and preserving contact as the gear rotates into complete engagement. The typical range of the helix angle is about 15 to 30 deg. The thrust load varies straight with the magnitude of tangent of helix angle. Helical is the most commonly used gear in transmissions. They also generate large amounts of thrust and make use of bearings to greatly help support the thrust load. Helical gears can be used to modify the rotation position by 90 deg. when installed on perpendicular shafts. Its normal gear ratio range is 3:2 to 10:1.
Bevel gears are used to change the path of a shaft’s rotation. Bevel gears have tooth that are available in straight, spiral, or hypoid form. Straight teeth have similar features to spur gears and possess a large influence when involved. Like spur gears, the standard gear ratio range for straight bevel gears is 3:2 to 5:1.
Spiral teeth operate the same as helical gears. They generate less vibration and sound when compared to straight teeth. The right hand of the spiral bevel may be the external half of the tooth, inclined to visit in the clockwise path from the axial plane. The left hand of the spiral bevel travels in the counterclockwise direction. The normal gear ratio range is 3:2 to 4:1.
In the hypoid gear above, the bigger gear is named the crown as the small gear is named the pinion.
Hypoid gears are a kind of spiral gear in which the shape is usually a revolved hyperboloid instead of conical shape. The hypoid equipment locations the pinion off-axis to the band gear or crown wheel. This enables the pinion to become larger in diameter and offer more contact area.