automotive gear is one of the mechanisms that play a very important role in the machine, can to reverse the direction of rotation and accelerate
Spur gears are a simple gear type, they take the form of a cylinder or disk with their teeth formed around the gears circumference, spur gears can be meshed together on parallel axles.
The worm resembles the thread of a screw, and are usually meshed with a worm wheel which looks similar to a typical spur gear. Worm gears are an excellent way to increase torque output while reducing rotational speed. Worm drives have ratios varying from around 10:1 to 500:1, worm gears do have a slight disadvantage in that they are not very efficient, a lot of energy can be wasted due to the sliding action of the gear teeth. The worm itself can have 1 or more teeth, although 1 tooth that follows around the length of the worm several times can look like more than one tooth being present. A worm with one tooth is called a single thread or single start, while a worm with more than one tooth is called a multiple thread or multiple start.
Intersecting but coplanar shafts connected by gears are called bevel gears. This arrangement is known as bevel gearing. Straight bevel gears can be used on shafts at any angle, but right angle is the most common. Bevel Gears have conical blanks. The teeth of straight bevel gears are tapered in both thickness and tooth height.
A double helical gear is similar to 2 separate helical gears joined together but mirrored, this helps eliminate the thrust that a single helical gear would create as in effect there is equal thrust in each direction cancelling each other out.
Helical gears have their teeth inclined to the axis of the shafts in the form of a helix, hence the name helical gears.
These gears are usually thought of as high speed gears. Helical gears can take higher loads than similarly sized spur gears. The motion of helical gears is smoother and quieter than the motion of spur gears.
Crown gears are a form of bevel gears, the teeth of crown gears project at right angles to the plane of the wheel. Crown gears are usually meshed with another bevel gear, but in some instances are meshed with spur gears.
Herringbone gears resemble two helical gears that have been placed side by side. They are often referred to as "double helicals". In the double helical gears arrangement, the thrusts are counter-balanced. In such double helical gears there is no thrust loading on the bearings.
A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line. Such a mechanism is used in automobiles to convert the rotation of the steering wheel into the left-to-right motion of the tie rod(s). Racks also feature in the theory of gear geometry, where, for instance, the tooth shape of an interchangeable set of gears may be specified for the rack (infinite radius), and the tooth shapes for gears of particular actual radii then derived from that. The rack and pinion gear type is employed in a rack railway.
source :
http://www.engineerstudent.co.uk/understanding_gears.html
http://mechanicalmania.blogspot.co.id/2011/07/types-of-gear.html
Following Type Of Gear
1. Spur Gear
2. Worm Gear
3. Bevel Gear
4. Double Helical Gear
5. helical Gear
These gears are usually thought of as high speed gears. Helical gears can take higher loads than similarly sized spur gears. The motion of helical gears is smoother and quieter than the motion of spur gears.
Single helical gears impose both radial loads and thrust loads on their bearings and so require the use of thrust bearings. The angle of the helix on both the gear and the must be same in magnitude but opposite in direction, i.e., a right hand pinion meshes with a
6. Crown Gear
7. Heringbone Gear
8. Rack and Pinion Gear
source :
http://www.engineerstudent.co.uk/understanding_gears.html
http://mechanicalmania.blogspot.co.id/2011/07/types-of-gear.html