Gears
The commonly used gears and
their arrangements can be seen in this section. With a help of teethed wheels we can transmit the energy in rotational,parallel and in perpendicular directions.In machines gears are used in places wherever the transmission of rotational force is taking place. Moreover the gears
are used to transmit the rotational force without any slip. It is used in places where there is a small distance for transmitting the rotational force (torque).
Types of gears
Gears are of many different types.
The following are some of the important gears
1. Spur gear
2. Helical gear
3. Double helical gear
4. Bevel gear
5. Rack and pinion gear
6. Worm and worm gear
7. Internal gear
8. Sprocket wheel
Spur gear
It is like a circular shaped one made
on a cylindrical metal having teeth cut in parallel to the axis of the cylinder. It is called as spur gear.
This gear is used to transmit the
rotary power only between two parallel shafts. It is capable of transmitting moderate force and speed. A smaller gear is called as pinion. Normally in gear box this type of gear is used for first and reverse gear speed operations.
Helical gear
It is also a circular shaped metal
made on a cylindrical metal having the teeth cut not parallel to the axis but in helical shaped cut at certain angle inclined to the cylinder’s axis.This type of gear is called as the helical gear.
We can transmit the rotational
power to two shafts which are either
parallel or non parallel through the helicalgear. Compared to straight spur gears more power can be transmitted through helical gears. This type of gear is used in synchromesh gear box and constant mesh gear box.
Bevel gear
In this gear the teeth are cut on the
top surface of the shaft in tapper. This
type of gear is generally used to connect the shafts which are perpendicular to each other and transmit the power in the perpendicular i.e. at 90o
angle direction.
Bevel gear is capable of withstanding
more power than other gears. The bevel gear is used in differential, pinion, crown,wheel, planet and sun gears.
Rack and pinion gear
In this arrangement teeth are cut
on a long flat metal bar called as rack. A small wheel called as pinion is in mesh with rack. In this way the rotating power of the pinion is transformed into a straight line or reciprocating motion. This type
of gears are used in the gear boxes in the steering system and in many mechanical machines.
Worm and worm gear
It is used to transmit the rotational
power by connecting two shafts that are perpendicular to each other. The gear which looks like a spur gear is called as the worm. The small shaft with the single start thread or multi start thread cut made on it is called the worm shaft.This type of gear is used in places where high speed reduction and high power transmission are obtained. It is used in steering gear box in automobiles.
Double helical gear or herringbone gear
On the circular periphery of the
cylindrical metal teeth are cut in the
shape of the English letter “V”. This gear is called as double helical gear or herringbone gear. This type of gear is used where more rotational power (torques) is transmitted.
Internal gear
The internal gear is the one in
which the teeth are cut internally on the inner circular metal pipe. This is called as the internal gear. This gear could transmit more power in short places.They are strong in structure. They are used in a small mechanisms and tractor mechanism.
Sprocket wheel
On a round metal wheel plate
teeth are cut outside. This wheel is not
in direct contact with the other wheel. In between the two wheels a chain is placed and the rotational power is transmitted through the chain. It is used in timing gears. Moreover it is also used in motor cycles.
